Disorders of the contractile structures 54

CHAPTER CONTENTS and is felt as a sudden, painful ‘giving way’ at the front of the Extensor mechanism 713 thigh. Alternatively, the muscular lesion may result from a direct contusion during contact sports (judo or American foot- Quadriceps strains and contusions ...... 713 ball), known as ‘Charley Horse’. Adherent vastus intermedius ...... 714 Patients who suffer an acute quadriceps strain will usually Tendinous lesions about the patella ...... 714 know right away. They are typically involved in sports requiring Rupture of the quadriceps tendon ...... 718 kicking, jumping, or initiating a sudden change in direction while running. Frequently, a sharp pain is felt, associated with Lesions of the infrapatellar tendon ...... 718 a loss in function of the quadriceps. Sometimes pain will not Lesions of the insertion at the tibial tuberosity . . . 719 fully develop during the athlete’s activity while the thigh is Patellar fracture ...... 719 warm; consequently, the extent of the injury is underesti- Patellofemoral disorders 719 mated. Stiffness, disability and pain then set in some time Introduction ...... 719 afterwards, e.g. late at night, and the following morning the patient can walk only with a limp.1 Mechanical theory ...... 719 Clinical examination shows a normal hip and knee, although Neural theory ...... 720 passive knee flexion is painful or both painful and limited, Clinical examination ...... 720 depending on the size of the rupture. Resisted extension of the Clinical manifestations ...... 722 knee is painful and slightly weak. As a rule, the lesion is in the 2 Strained iliotibial band 724 rectus femoris, usually at mid-thigh level. The affected muscle belly is hard and tender over a large area. Sometimes a hae- Flexor mechanism 725 matoma can be palpated. In serious lesions, a space can be Hamstring strains ...... 725 detected by palpation. This is particularly the case in major Biceps tendinitis ...... 726 ruptures just above the suprapatellar tendon, which occur mainly in patients over 40 years of age.3 In such cases, there is Lesions of the upper tibiofibular joint ...... 726 not only pain but also weakness during resisted extension, and Lesions of the pes anserinus ...... 727 the patient is unable to straighten the knee actively over the Strained popliteus muscle 727 last 30°. Lesions of the gastrocnemius 729 Ultrasonography is an excellent imaging modality for visual- izing the quadriceps muscles; it has the ability to image the muscles dynamically and assess for bleeding and haematoma.4 Extensor mechanism Development of myositis ossificans as a complication of a thigh contusion is not uncommon in adolescents and young adults.5 It occurs in 9% of quadriceps contusions and seems to Quadriceps strains and contusions be associated with five risk factors (knee motion less than 120°, injury occurring during American football, previous quadriceps A muscular tear of one of the quadriceps bellies is a common injury, delay in treatment of more than 3 days and ipsilateral disorder in sprinters and soccer players. An abrupt, vigorous knee effusion).6 Early diagnosis is important and is usually contraction during a sprint breaks some of the muscle fibres made with the help of sonography.7,8 There is no proper

© Copyright 2013 Elsevier, Ltd. All rights reserved. The Knee treatment but the lesion undergoes spontaneous cure After the friction, active isometric contractions are done within 2 years.9 Therapy with deep transverse massage is over 5–10 minutes. Again, this is carried out in a fully relaxed contraindicated. position, so that the contraction cannot exert tension on the healing tissue (see Ch. 5). Treatment Treatment with deep friction and contractions is given daily for the first week and on alternate days from the second Initial haemorrhage may be reduced by elastic strapping and week onwards. In athletes, there is a significant tendency an ice bag over the lesion. In the case of a contusion, holding for the lesion to recur and the patient should not restart a the knee in 120° of flexion for 24 hours following a quadriceps training programme until a week after complete clinical cure. contusion also appears to shorten the time needed for the In the meantime, treatment should continue. The training 10 patient to return to unrestricted full athletic activities. programme must be built up gradually over the following Minor ruptures in the quadriceps muscle require the same 3–4 weeks. treatment as muscular lesions elsewhere. As soon as the patient is seen, the lesion is infiltrated thoroughly with 50 mL of pro- caine 0.5%. From the next day on, deep transverse friction is Adherent vastus intermedius given, followed by active isometric contractions with the muscle in a shortened position. This condition occurs typically after a fracture of the femur. When the rupture is major, operative suture may be advised, There is gross limitation of flexion, whereas the other knee especially if the patient is an athlete with high functional movements are all full-range. Only surgical treatment can demand on the knee extensors. It is then important that surgi- achieve an acceptable outcome. cal treatment is undertaken as soon as possible. Technique: deep friction to the quadriceps muscle Tendinous lesions about the patella The patient sits with the knees outstretched. Flexion at the The quadriceps tendon has a superficial and a deep layer. The hips, together with maximal extension of the knees, induces superficial layer runs without interruption from the quadriceps complete relaxation of the quadriceps. The physiotherapist muscle, over the patella to the tibial tuberosity. The deep layer stands at the patient’s side. The correct level is sought. The inserts all around the patellar border, effectively making the fingers of one hand are placed deep to the affected fibres. The patella a sesamoid bone in the tendon. Tendinous lesions there- other hand can reinforce the palpating one. The thumbs are fore occur not only at the inferior aspect of the bone but also placed laterally to be used as a fulcrum. By flexion of the at the superior, medial and lateral borders. Tendinosis about fingers, during an upward-drawing movement, the physiothera- the patella is a typical overuse phenomenon in sports character- pist drives all the fibres between fingers and femur (Fig. 54.1). ized by high demands on leg extensor speed and power, such At the end of the movement, the fingers are slightly extended as volleyball, basketball, soccer and athletics. It was first and brought back to the previous spot, under the lesion. The described by Sinding-Larsen in 192111 and Johansson in 1924.12 skin must move with the fingers. Since this is an extremely Kulund13 and Ferretti14 also reported cases of tendinosis at the tiring technique, periods of rest must be built into the treat- upper border of the patella. Cyriax15 describes three possible ment session, which lasts about 20 minutes. sites: the upper border (suprapatellar tendinosis), the apex – the classic ‘jumper’s knee’ (infrapatellar tendinosis) and at either side of the patella (tendinosis of the quadriceps expan- sion) (Fig. 54.2). The lesion was uncommon until the mid- 1960s, when the syndrome of jumper’s knee became more and more frequent because of increased training and higher per- formance goals for athletes.16,17 During the last few decades, these lesions have reached epidemic proportions18; in sports medicine centres, patellar tendinopathy is one of the leading reasons for consultation and often contributes to the decision to give up an athletic career.19 The history is obvious: during or after exertion, there is localized pain at the front of the knee. In mild examples, there is probably only a little pain after activity, whereas in a severe case pain forces the athlete to stop, and pain at rest can also supervene. The patient also states that walking upstairs or standing up from sitting is painful. The lesion can be classified by its symptoms into four stages (Table 54.1).13,20,21 Clinical examination reveals a normal knee with a full and painless range of movement and normal ligamentous tests. Only resisted extension is painful or uncomfortable. When the history suggests a slight quadriceps tendinitis but resisted Fig 54.1 • Friction in minor rupture of the quadriceps. extension is negative, the patient should take part in a training

714 Disorders of the contractile structures C H A P T E R 5 4

and the hyaline inflammatory tissue (usually the middle portion of the patellar ligament) is removed.30,31 However, the benefits of open tenotomy can be questioned on the basis of the results, which show a success rate that varies between 58%14 and 78%.32 Sporting success is seen in about 50% of tenotomy patients, with a median time to return to pre-injury level of activity of 10 months.33 1 Eccentric training as a treatment option for tendinopathy has gained credit in recent decades. The technique was first 2 presented by Curwin and Stanish in 1984, with encouraging results.34 The programme is based on eccentric drop squats, 2 which are performed with some level of discomfort. During 3 the programme, the athlete should be removed from sports activity. When training becomes pain-free, load is increased by first increasing the speed of the eccentric phase and then adding weight.35,36 Our advice is to treat all peripatellar lesions with either a local infiltration of triamcinolone or a series of deep transverse friction.37 At the upper border and the apex, infiltration with triamcinolone can be used safely and with very good Fig 54.2 • Localizations of quadriceps tendinitis (with permission results, providing the injection is done exactly at the right 15 from Cyriax : p. 408): 1, suprapatellar; 2, expansion; 3, infrapatellar. spot, using a weak solution (10 mg/mL) and according to the general principles of infiltration. Deep transverse friction is preferred if the lesion is too extended for infiltration. If a small 21 Table 54.1 Staging of quadriceps tendinitis spot remains resistant to treatment, it can subsequently be infiltrated. Stage Symptoms Lesions of the quadriceps expansion at either side of the I Pain after activity patella respond extremely well to deep transverse friction but II Pain at onset, disappearing during activity and reappearing infiltration is of no use at this site. after it Because relative rest is always the first measure in tendinous lesions, the patient should not return to athletics until com- III Continuous pain, inability to perform plete remission of the lesion has been achieved. After success- IV Weakness due to rupture ful treatment, and in order to prevent recurrence, it is important to detect the possible causes of the tendinitis (inappropriate or faulty training programme or structural factors) and to 38 session and be re-examined immediately thereafter; this will correct these. probably reveal a minor lesion. In recalcitrant cases, one or two infiltrations with sclerosing 39 Palpation identifies the site. To make the deeper layers of solution to the tenoperiosteal border can be tried. the tendon accessible for the palpating finger, the patella must Technique: deep friction to the suprapatellar tendon be tilted as much as possible (see pp. 716 and 717). Conventional radiographic techniques are of no use in the The patient sits on the couch with the knee completely diagnosis of quadriceps tendinitis. Ultrasonography, however, extended and the hip flexed, so that the quadriceps muscle is seems to have some value in staging the disorder.22–24 fully relaxed. On magnetic resonance imaging (MRI), swelling of the The patella must be tilted in such a way that the affected tendon and changes in the intrasubstance signal may be spot can be reached. This can be achieved by pressing the present.25 However, the sensitivity and specificity of MRI is lower pole of the patella posteriorly with the web of the thumb 75% and 29%, respectively. In younger patients with relatively or with thumb and index finger, which steadies the bone mild symptoms, MRI does not show significant changes and in and forces the upper border upwards and forwards. With the older, active patients changes may be present in asymptomatic middle finger of the other hand, the tender area can now be knees.26,27 sought more easily. It is important to move the finger as far as possible under the inclined patella in order to catch the tendi- nous fibres of insertion deep under the bone. Deep friction is Treatment performed by pressing the tendon between the middle finger Classically, conservative treatment for patellar tendinopathy and the superior aspect of the patella (Fig. 54.3). The index consists of rest, ice, taping and anti-inflammatory drugs. Other finger is used to reinforce the middle finger. The thumb is modalities, such as electrotherapy, ultrasound, laser therapy placed as far distally as possible on the leg and used as a and extracorporeal shock wave therapy, have also been used.28 fulcrum. The friction consists of a to-and-fro movement of the If these measures are insufficient or fail to relieve the symp- whole forearm and hand, in a transverse direction over the toms, surgery is usually advised.29 The patellar tendon is incised tendinous fibres.

715 The Knee

Fig 54.3 • Deep friction to the suprapatellar tendon.

Twenty minutes of really hard friction are needed to produce a good result, which may be expected after 10–20 sessions. Technique: infiltration to the suprapatellar tendon The patient sits with the knee outstretched and the hip flexed, so that the quadriceps is fully relaxed. The patella is fixed as described earlier. The upper edge of the patella is marked and the tender area identified. Usually it lies at the medial edge of the upper border, less frequently at the lateral edge of the upper border, and as a rule it is no larger than 1 or 2 cm. A spot is chosen about 1.5–2.0 cm above the centre of the affected area. A 3 cm needle fitted to a 2 mL syringe is intro- duced at this spot and moved in the direction of the patella (Fig. 54.4). The more the patella is tilted, the better the needle can reach the affected area. Small injections are given only when the tip of the needle is felt to pierce tendinous structure and touch bone. Considerable resistance is felt during the injection. Caution is taken to infiltrate the whole tender area by the usual technique of fanwise insertions and withdrawals. Significant discomfort may be expected for a day or two. If, after 2 weeks, clinical examination still evokes pain, a second injection must be given. Two or three injections cure most patients. Technique: deep friction to the quadriceps expansion Infiltration of the quadriceps expansion seems to have little therapeutic effect. Deep transverse friction is therefore the only appropriate approach. Full and lasting relief is always attained, provided the massage technique is correct. Once again, the patient sits with the knees outstretched and the quadriceps muscle fully relaxed. The therapist sits level with the patient’s knees. With the thumb of one hand, the Fig 54.4 • Infiltration of the suprapatellar tendon. The patella is patella is pushed distally and over towards the affected side. tilted (small arrows) by pressing on the inferior pole (large arrow).

716 Disorders of the contractile structures C H A P T E R 5 4

This allows the edge of the patella to project outwards. The little finger of the other hand is extended as far as possible. The ring finger, reinforced by the middle finger, is placed under the patellar edge in such a way that it presses upwards, squeez- ing the tendinous fibres against the posterior aspect of the patella. Caution is observed so as to bring the hand into full supination, which means that the operating finger is horizontal, with pressure being applied against the back of the projecting edge of the patella. A vertical finger just presses against the femur and no friction on the tenoperiosteal junction results. Hand and forearm are held in line with the tibia, and friction is produced by a horizontal movement along the patellar edge (Fig. 54.5). Twenty minutes’ friction, three times a week for 2–3 weeks, nearly always results in cure. Technique: deep friction to the infrapatellar tendon Infrapatellar tendinitis is by far the most common tendinitis at the patella. The lesion lies over an area of 1–2 cm at the infe- rior pole of the patella. In order to make this area more acces- sible, pressure is exerted at the upper part of the patella, in the following manner. The physiotherapist stands level with the extended knee. One hand is placed just above the patella, so that the web of the thumb can exert downward pressure. This stabilizes the patella and tilts the apex upwards, so that the tender area can be sought with great accuracy. Friction is given with the middle finger of the other hand, reinforced by the index finger. The thumb is placed as far proximally as pos- sible on the thigh. Pressure is exerted upwards, so that the lesion becomes squeezed between finger and bone (Fig. 54.6). Sometimes a large osteophyte can be palpated at the apex; if so, it is important to investigate to establish which side of the osteophyte the tenderness is located. Friction is given by alter- nate adduction and abduction movements at the shoulder, which draw the finger strongly along the inferior border of the patella. Twenty minutes of friction on alternate days, for 10–20 sessions, is sufficient for cure. If no improvement is seen after 10 sessions, the patient is referred for triamcinolone infiltration. Technique: infiltration of the infrapatellar tendon The patient sits supine with the quadriceps relaxed. The thera- pist presses with one hand on the superior border of the patella, in such a way that the inferior pole moves distally and upwards. This makes the infrapatellar tendon accessible to the palpating finger. The exact location of the lesion is now identi- fied, in the way described earlier. The lower pole mustbe palpated very carefully, to determine the exact borders of the Fig 54.5 • Deep friction to the quadriceps expansion. lesion. As already mentioned, caution should be observed in locating the lesion when an osteophyte is present. Once the exact location is identified and the borders marked tenoperiosteal junction. The infiltration is now given using a on the skin, a point is chosen 1.5–2 cm inferior to the midpoint series of small droplets along the inferior border. Considerable of the affected area. A thin 3 cm needle is fitted with a syringe, pressure has to be exerted on the syringe to push the drug in. containing 2 mL of triamcinolone. With the patella remaining Care is taken to inject only when the tip of the needle is felt tilted, the needle is inserted at the identified point and moved to hit bone. upwards, through the infrapatellar tendon, until it hits bone After the injection, the patient should take relative rest for (Fig. 54.7). It is important to reach the posterior aspect of about 10 days. Usually, considerable discomfort is experienced the patellar apex because most lesions lie deeply at the for 24–48 hours. The patient is seen again after 2 weeks. If

717 The Knee

All types Rest until complete remission has been achieved Prophylaxis Structural factors? Training? Suprapatellar tendinitis One or two infiltrations with 10–20 mg of triamcinolone Or deep transverse frictions 3 times a week, for 10-20 sessions Quadriceps expansion Deep transverse friction 3 times a week for 6-10 sessions Infrapatellar tendinitis

Extensive lesions

Deep friction 3 times a week Cure for 10-20 sessions

Triamcinolone Smaller lesions Cure Fig 54.6 • Deep friction to the infrapatellar tendon. 10 mg, once or twice

No response Prolotherapy Cure

Surgery

Fig 54.8 • Treatment of quadriceps tendinitis.

pain is still elicited by resisted extension, infiltration is repeated. Usually 1–3 injections are required to obtain total and lasting relief. Return to sport must be gradual, and a training programme that does not impose too much strain on the quadriceps during the first few weeks is advised. An underlying biomechanical factor as the basis for a possible recurrence should be sought.40,41,38 Treatment of quadriceps tendinitis is summarized in Figure 54.8.

Rupture of the quadriceps tendon

Rupture of the suprapatellar quadriceps tendon is an uncom- mon injury. Most of the patients are elderly, and sometimes there is diagnostic confusion with other causes of inability to use the legs, such as a mild stroke.41 The mechanism of injury usually involves forced hyperflexion or rapid extension from a weight-bearing position.42 Pain, swelling, a palpable gap and inability to straighten the leg against resistance are the cardinal features. Treatment is operative repair.

Lesions of the infrapatellar tendon

Tendinitis of the infrapatellar tendon (ligamentum patellae) is unusual and occurs only in rheumatic disorders. Inflammation of the peritendineum, with pain, thickening and coarse crepi- Fig 54.7 • Infiltration of the infrapatellar tendon. The patella is tus, can be found. Treatment consists of triamcinolone infiltra- pressed distally, which moves the inferior pole upwards (arrows). tion along the surface of the tendon.

718 Disorders of the contractile structures C H A P T E R 5 4

A patellar tendon rupture may be caused by acute or chronic Patellofemoral disorders excessive traction force.43 The tendon is then pulled from the lower pole of the patella.44 Degenerative rheumatic disease may also give rise to rupture of the infrapatellar tendon.45,46 Introduction Treatment is surgical.47 Patellofemoral pain is a common condition. About 25% of the population will, at some stage in their lives, suffer from patello­ Lesions of the insertion at the femoral symptoms.57 There is no clear consensus in the litera- tibial tuberosity ture concerning the terminology, aetiology and treatment for pain in the anterior part of the knee. The term ‘anterior knee Tenoperiostitis pain’ is suggested to encompass all pain-related problems. By excluding anterior knee pain caused by intra-articular This exceptional lesion sometimes occurs in athletes. Resisted disorders, peripatellar tendinitis or bursitis, plica syndromes, extension of the knee is painful at the insertion of the infrapa- Osgood–Schlatter disease and other rarely occurring condi- tellar tendon. Palpation reveals the exact spot at the tibial tions, it is suggested that those remaining patients with a clini- tuberosity. Friction can be tried but is not always very helpful, cal presentation of anterior knee pain could be diagnosed as and treatment mostly consists of one or two infiltrations with having patellofemoral pain syndrome (PFPS).58 The term a small amount of triamcinolone. chondromalacia patellae, although once used as an all-inclusive term for anterior knee pain, is now only accepted to describe Apophysitis pathological lesions of the patellar articular cartilage found at Osteochondrosis of the tibial tuberosity, or Osgood–Schlatter arthroscopy or arthrotomy. A diagnosis of ‘chondromalacia 59,60 disease, occurs in boys between 10 and 15 years of age.48 patellae’ for anterior knee pain is made far too often. Stou- The typical symptoms are local pain during sports or when gard detected cartilaginous lesions at the posterior aspect of 61 walking upstairs. Local tenderness makes kneeling impossi- the patella in almost every knee joint at autopsy and Paar and ble.49 Clinical examination reveals local ache during resisted Riehl observed damage to the patellar cartilage in almost every 62 extension of the knee. Palpation shows an enlarged, tender and operated knee. 63 warm tuberosity. The cause of patellofemoral pain is unknown. Currently, Radiography confirms the diagnosis and is important in there are two theories to explain its origin: the mechanical and 64 differentiating the condition from more serious disorders the neural theory. such as osteomyelitis, arteriovenous malformations and osteosarcoma.50 In Osgood–Schlatter disease, nothing other than reduction Mechanical theory of athletic activity should be advised. Spontaneous recovery takes place in 2 years, often with a permanently enlarged Most authors stress the importance of the congruency bet­ 65–67 tuberosity (knee knob). ween the articular surfaces of the femur and the patella. During the last decade, a great deal of emphasis was given to the idea of imbalance of the soft tissues surrounding the patella Patellar fracture as the prime cause of patellar ‘maltracking’. The soft tissue balance is particularly critical in the first 20° of knee flexion, Most patellar fractures are stellate fractures, occurring after a where the position of the patella in relation to the femur is fall or a direct blow (dashboard injuries). In the last decade, determined by the interaction of the medial and the lateral an increasing number of patellar fractures in association with soft tissue structures; after this 20° of motion, the patella total knee replacement have been described.51,52 engages the femur and the bony architecture becomes more Clinical examination shows warmth, a capsular pattern and important for the position of the patella relative to the femur.68 a joint that contains blood. Resisted extension is markedly Any imbalance in the soft tissue structures in the first 20° weak and painful. The combination of a gross articular pattern of flexion will mean that the patella does not encounter the and marked quadriceps signs shows that the part of the quad- trochlea optimally, which may lead to undue stress on various riceps mechanism that overlies the knee joint must be at fault. tissues around the joint and thus to pain. The imbalance may Radiography confirms the diagnosis. be the consequence of multiple biomechanical defaults. Weak- In young patients, an uncomplicated fracture heals quickly ness of the vastus medialis obliquus is thought to be the single but early osteoarthrosis has to be expected.53 When accurate most important factor causing momentary patellar subluxa- reduction and stable fixation cannot be achieved, partial or tion.69 Also, the passive stabilizing structures are usually more total patellectomy must be considered and seems to produce extensive and stronger on the lateral than on the medial side. satisfactory results.54,55 Active stabilization is provided by the quadriceps muscle – on Transverse fractures are uncommon, except in an elderly the lateral side the vastus lateralis and on the medial side the person with an osteoporotic patella. After the trauma, the vastus medialis. The fibres of the vastus medialis are divided patient can walk with pain; because the capsule enclosing the functionally into two compartments: the vastus medialis patella is not ruptured, displacement is avoided and therefore longus and the vastus medialis obliquus (VMO). The latter the disability is minor.56 does not play a role in active extension of the knee but keeps

719 The Knee

suffering from persistent patellofemoral pain. This subgroup was treated with a new method of intraosseous drilling and decompression. Of the patients so treated, 90% experienced pain relief more than 3 years postoperatively, which may indi- cate osseous hypertension as a cause of the pain.81 1 Some authors have sought the origin of the pain in soft tissue structures around the knee. Nociceptive nerve fibres and neural markers (S-100 protein, neurofilament protein, sub- stance P and neural growth factor) have been demonstrated 2 in the medial and lateral retinacula and in the infrapatellar fat pad.82,83 From the existing studies it can be concluded that both theories are complementary rather than exclusive: the neural factor precipitates the symptoms in patients with certain bio- mechanical anomalies who subject their knee to overuse.

Clinical examination

It is important to stress the fact that most anterior knee pain is not caused by patellofemoral disorders but stems from infra-, supra- or peripatellar tendinitis, or a coronary ligament lesion. A basic functional examination should therefore always be Fig 54.9 • Active medial stabilization is provided by the vastus performed first (seeBox 54.1). However, if specific symptoms medialis obliquus (VMO): 1, VMO; 2, patella. warrant, and the basic functional examination is totally nega- tive, attention must be directed towards any peculiarities the patella centred in the trochlea of the femur throughout found during inspection of the patella and surrounding tissues. knee extension.70 The VMO is the only active stabilizer of the patella (Fig. Inspection on standing 54.9); therefore the timing and the amount of activity in the Alignment of the lower extremity is evaluated first by observ- VMO is critical to patellofemoral function and it is hypothe- ing the patient standing. Excessive varus or valgus of the sized that small changes in its activity may have considerable extremities and internal femoral rotation are often associated effects on the patellar position.71 Electromyography (EMG) with an extensor mechanism malalignment. Hyperextendable studies have revealed that, in patients with patellofemoral pain, knees may also contribute to the development of anterior knee the VMO contracts at a significantly slower rate than the vastus pain. McConnell points out that shock absorption throughout lateralis, whereas in normal subjects the reflex response time the lower leg then comes from internal rotation of the femur, of both muscles is equal.72–74 A recent MRI study examined rather than from knee flexion.84 VMO size in patients with patellofemoral problems and found atrophy in all of them. Although it is not clear whether this atrophy is a result or a cause of PFPS, there is obviously a Inspection on sitting strong relationship between the two.75 Some of the most important observations are made with the Other biomechanical factors that may contribute to patient in the sitting position, with the legs bent to 90°. The the development of patellofemoral pain are tightness in the position of the patella is assessed by viewing the knee from lateral structures, increased Q angle (see p. 722) and faulty the lateral and the frontal aspects. In a lateral view (Fig. 54.10), foot mechanisms.76–78 In a retrospective study on 282 male the patella should be situated on the distal end of the femur, and female students enrolled in physical education classes, with the proximal patellar pole level with the anterior femur Witvrouw et al found a significant correlation between four and the anterior surface of the patella in line with the tibial parameters and the development of patellofemoral pain: a shaft. In ‘patella alta’, the upper border of the patella sits more shortened quadriceps muscle, an altered VMO muscle reflex on the anterior surface of the femur and ‘faces towards the response time, a decreased explosive strength and a hypermo- ceiling’. Viewed from anterior, a normally positioned patella bile patella.79 faces straight ahead (Fig. 54.11); ‘outfacing’ and ‘infacing’ patellae are easily recognized in this position. Neural theory Attention is also directed to the alignment of the patella and the patellar tendon in relation to the tibial tuberosity and the The normal articular cartilage is aneural, so defects in the tibial crest. surface are not thought to produce pain. It has therefore been The bulk and the level of insertion of the VMO muscle is suggested that irritation of the subchondral bone produces the then assessed. The patient is asked to hold both knees actively pain.80 Schneider et al could reproduce the typical pain sensa- at 45° of flexion. Normally, the VMO is seen as a substantial tion by raising intrapatellar pressure in about 40% of patients muscle, arising from the adductor tubercle and medial

720 Disorders of the contractile structures C H A P T E R 5 4

Fig 54.10 • In a lateral view the proximal pole of the patella should be level with the upper thigh.

Fig 54.12 • The normal Q angle is about 10° in males and 15° in females.

comparing the height of the medial patellar border with that of the lateral patellar border. The two borders should be level compared to the horizontal. The anteroposterior component evaluates the position of the inferior pole of the patella relative to the superior pole. Fig 54.11 • Viewed from anterior, normally positioned patellae face A rotation of the patella is determined by examining the straight ahead. position of the long axis of the patella, relative to the long axis of the femur. intermuscular septum and inserting into the upper third to half of the medial patellar border. In the obese knee, it is advisable to palpate along the inner border of the patella during active Q angle contraction in 45° of flexion. Next the Q angle is measured. This is the angle at the centre of the patella between two imaginary lines, from the anterior Inspection in the supine position superior iliac spine and from the tibial tuberosity to the geo- metric centre of the patella. A Q angle of up to 10° is normal The knee is in almost full extension (a small cushion is placed in the male and up to 15° in the female (Fig. 54.12).85 in the popliteal fossa) and the quadriceps is fully relaxed. The position of the patella in relation to the femur is observed. In the obese knee it may be necessary to palpate the patellar Passive movements of the patella borders with one hand and the femoral condyles with the Patellar mobility is best assessed on a knee flexed to ± 20° (the other. Four components affect the patella statically and dynam- knee resting on a cushion or on the thigh of the examiner), ically: lateral glide, mediolateral tilt, anteroposterior tilt and with the quadriceps completely relaxed. The examiner’s rotation. An optimal patellar position is one where the patella thumbs are placed on the medial border of the patella and the is parallel to the femur in the frontal and the sagittal planes index fingers on the lateral border as attempts are first made and midway between the two condyles of the femur when the to push the patella laterally and then medially. Quantitating knee is flexed to 20°.84 the degree of mobility can be done by dividing the width of The glide component is determined by measuring the dis- the patella into four longitudinal quadrants (Fig. 54.13). In tance from the mid-pole of the patella to the medial and lateral normal subjects, the patella cannot be displaced more than femoral epicondyles. The patella should be precisely in the three quadrants laterally and should allow a medial shift over middle. The amount of mediolateral tilt is detected by at least one quadrant. When the patella is moved in a medial

721 The Knee

Fig 54.13 • Quantitating the degree of mobility can be done by dividing the width of the patella into four longitudinal quadrants. direction, it should initially remain parallel to the femur and not tilt during the first quadrant of the movement. During lateral movement of the patella, the examiner is looking not only for patellar mobility but also for any associated apprehension in the subject: as the patella tends to slip over Fig 54.14 • Lateral pull sign: the patella moves laterally during the lateral condyle of the femur, the patient suddenly contracts contraction of the quadriceps. the quadriceps muscle and draws the patella back. This sudden reflex would not be present if the patella was not apt to sub- luxate, and is typical of cases of subluxation. Box 54.1

Inspection during active movement Clinical examination of the patellofemoral articulation Close observation of the patella in relation to the femur is then • Inspection standing continued during active contraction of the quadriceps. The • Inspection sitting with the knees hanging over the edge of the couch patella should be pulled directly superiorly, or superiorly and • From anterior slightly laterally. Excessive lateral displacement represents • From lateral lateral overpull by the quadriceps and has been referred to as • Contraction of the quadriceps at 45° of flexion the ‘lateral pull sign’ (Fig. 54.14).86 • Inspection in the supine position Further observation is made during active flexion of the • Position of the patella: four components knee. The patella should remain centred on the trochlea. A • Q angle patella which was sitting slightly lateral on the trochlea at full • Passive movements of the patella extension should move medially to be centred on the trochlea • Mediolateral glide as soon as the knee flexes. • Apprehension Clinical examination of the patellofemoral articulation is • Mediolateral tilt summarized in Box 54.1. • Active contraction of the quadriceps • Active flexion of the knee Clinical manifestations

From a clinical perspective, patellofemoral problems in the falls to the ground and feels something is out of place at the skeletally mature patient fall into three broad categories: patel- lateral aspect of the knee. When the leg is straightened, there lofemoral instability (subluxation or dislocation), patellofemo- is a loud click and extension becomes possible at once. For ral pain with malalignment but no episodes of instability, and some days afterwards the knee swells and hurts, consequent patellofemoral pain without malalignment.87 upon traumatic arthritis. Sooner or later the incident recurs. More often, there is a subluxation of the kneecap. The patient does not report the dramatic features described above Recurrent dislocation and subluxation but merely a ‘catching’ of the knee, followed by medial pain. of the patella The latter is caused by tearing of the medial capsular structures Dislocation mostly affects girls and begins at puberty. The history and should be differentiated from lesions of the medial is that of a knee suddenly and painfully giving way. The youngster meniscus.88

722 Disorders of the contractile structures C H A P T E R 5 4

1 2 4

3

5

Fig 54.16 • Laterally tilted patellae.

Most patients with knee pain attributed to PFPS are young Fig 54.15 • Anatomical changes in recurrent subluxation of the women. The common symptom is of a dull and vague aching patella: 1, increased patellar mobility; 2, decreased Q angle; behind the kneecap during and after physical activity, espe- 3, outfacing patella; 4, vastus medialis deficiency; 5, fat pad cially during body-weight loading of the lower extremities enlargement. (walking up- or downstairs and squatting). The knee is usually also sore in a sitting position and a few patients have nocturnal pain too.97 Clinical examination often reveals an enlarged fat pad and Routine clinical examination reveals nothing. There is a patella alta. There is deficiency or atrophy of the VMO. Some full and painless range of movement, with normal end-feels. authors find a significantly decreased Q angle.89 Lateral patellar Resisted extension is strong and painless. Inspection may reveal mobility is increased (more than three-quarters of the width some typical abnormalities. Excessive varus or valgus position of the patella) and apprehension can often be provoked during of the lower extremities is often associated with a malalign- glide mobilization of the patella (Fig. 54.15). ment of the patella. The position of the patellae is first assessed in the sitting position. Laterally tilted patellae (Fig. 54.16) Treatment appear to be ‘looking’ up and over the examiner’s shoulders In acute or recurrent dislocation, surgical intervention is towards the ceiling, the so-called ‘grasshopper eyes’ kneecap. advised but only after puberty, when the epiphysis has closed. The VMO is then assessed by asking the patient to hold the Good subjective results are to be expected in about 80% of knees actively at 45° of flexion. In patients with atrophy of the patients.90 VMO muscle, there is a visible and palpable lack of muscular In recurrent subluxation, the decision to operate should not tissue at the upper medial border of the patella. be taken lightly because it has been demonstrated that long- The Q angle is often increased in patients with PFPS. term results continue to show an incidence of persistent insta- Another common finding is tightness of the inert lateral struc- bility and late patellofemoral arthrosis.91–93 Arthroscopic release tures which make the patella tilt laterally: the medial border only gives a satisfactory result in 40% of cases.94 Treatment of of the patella is higher than the lateral border, the undersurface patellofemoral instability should therefore be conservative, of which is hard to palpate. Any attempt to push the patella surgical interventions being reserved for patients who do not medially results in more anterior tilting of the medial border. respond adequately. Conservative treatment consists of inten- If the lateral structures are tighter more distally on the patella, sive functional vastus medialis rehabilitation, together with the it externally rotates, and if the tightness is greater in the supe- use of a brace (see treatment of PFPS, p. 1143). rior pole, the patella will internally rotate during lateral pres- sure. Slight tightness of the lateral structures is revealed by a decreased medial glide: a medial displacement of only one Patellofemoral pain syndrome quadrant indicates a tight lateral retinaculum. Again, the patella without subluxation tilts laterally during the manœuvre. The source of pain in ‘patellofemoral pain syndrome’ cannot Excessive lateral movement of the patella during active con- be adequately explained. The hypothesis is that patients with traction of the quadriceps (the ‘lateral pull sign’) or during PFPS have lateral displacement of the patella within the active extension of the knee in a sitting position indicates femoral trochlea.95 This lateral ‘malalignment’ may result from predominance of lateral forces. They are common findings in a number of factors, including malalignment of the lower PFPS (Fig. 54.17). extremity and/or the patella, tight lateral soft tissue structures The classic radiological examination techniques to visualize and muscular imbalance of the lower extremity. All may the patellofemoral articulation are the Merchant98 and Laurin99 lead to areas of increased stress on the patellofemoral joint views, whereby the joint surfaces are visualized with the knee and pain.96 flexed to 45° and 30° respectively. MRI has also been found to

723 The Knee

been proposed that training causes changes within the nervous 1 system that allow an individual to coordinate the activities of muscle groups better.108 Biofeedback machines are extremely useful to facilitate this process.109 Adding some hip adduction 2 in training will also cause an increase in VMO activity relative to VL.110 If symptoms persist despite a conservative treatment pro- 3 gramme, surgery may be indicated. An arthroscopic approach, with shaving of the affected area111 and/or lateral release of the 112,113 4 lateral retinaculum, is recommended. Before deciding to operate, however, it is important to remember that the long- term results are not as good as might be hoped.114,115

Patellofemoral arthrosis This can occur after a flake fracture of the articular surface of the patella.116 It is not clear whether chondromalacia patellae precedes osteoarthritic changes because the anatomical loca- tion of the two conditions differs. Chondromalacia is most often found near the median ridge, whereas osteoarthrosis first Fig 54.17 • Anatomical changes in PFPS: 1, decreased patellar appears on the very medial side of the patella.13 Erosion of the mobility; 2, increased Q angle; 3, lateral tilted patella; 4, cartilage at the medial edge may start before the age of 20 and hypertrophied lateral bands. has been shown to be present in three-quarters of individuals be an accurate and reproducible method of measurement of by the age of 30. the patellar tilt angle.100,101 As in other localizations of osteoarthrosis, radiographic signs Arthroscopy is of little value in the diagnosis of PFPS. The do not always equate with symptoms. Sometimes the patient incidence of damaged cartilage in asymptomatic patients is so is aware only of grating or cracking when walking upstairs. high that arthroscopy on its own cannot determine whether Alternatively, the symptoms may be very similar to those in chondromalacia: anterior pain when walking upstairs, squatting the symptoms should be attributed to chondromalacia. Hertel 117 detected lesions of the articular surface of the patella in about or sitting with bent knees. Palpation during squatting reveals 50% of routine arthroscopies.102 Paar and Schneider found pain, together with ‘crackling’ and ‘popping’ sensations. clear damage to the cartilage in 67% of the joints in which they Treatment depends on the severity of the symptoms. Intra- undertook arthroscopies.103 These two series establish that articular injections with hyaluronan has proven to be an effec- arthroscopic lesions occur far more frequently than do clinical tive treatment modality for patellofemoral arthrosis, with beneficial effects on pain, function and patient global assess- manifestations, and that overestimation of disease is a hazard 118,119 if diagnosis is based totally on the result of arthroscopy. ment. In intractable cases, patellofemoral arthroplasty can be advised.120 Treatment In a number of patients, the condition seems to be self-limiting, as demonstrated by Sandow and Goodfellow, who reported Strained iliotibial band spontaneous cure in more than 20% of anterior knee syn- dromes. Of 54 girls suffering from PFPS, only 9 were perma- The iliotibial band, a thick extension of the fascia lata, inserts nently unable to participate in sports after a follow-up period at the tibial tubercle of Gerdy. The band lies anterior to the of 4 years.104 flexion–extension axis of the knee in extension and posterior Many different treatment protocols for PFPS have been in flexion. The tensor fasciae latae, acting through the band, is described in the literature. It is clear that, if abnormal tracking thus a weak external rotator and extensor of the knee. Iliotibial of the patella is believed to be the reason for the pain, the band friction syndrome is an overuse injury usually seen in initial treatment must be to try to restore normal alignment. military personnel, cyclists and long-distance runners.121 With An optimal patellar position is achieved by stretching the tight an incidence of between 1.6 and 12%, it is the most common lateral structures and by changing the activation pattern of running injury of the lateral knee in long-distance runners.122,123 the VMO.68 The presumed pathogenesis is that during activities involv- Stretching is performed passively by the therapist. However, ing repetitive knee flexion (such as running), the iliotibial band the most effective stretch to the shortened retinacular tissue repetitively shifts forwards and backwards over the lateral is obtained by sustained low load, using tape, which facilitates femoral epicondyle, causing friction and thus inflammation of a permanent elongation of the tissue.105–107 the iliotibial band (Fig. 54.18). Friction thus occurs at, or Specific training of the vastus medialis includes timing and slightly below, 30° of flexion.124 This can produce either irrita- intensity of the VMO relative to the vastus lateralis (VL). tion and subsequent inflammatory reactions within the ilio­ Ideally, the VMO should come in slightly earlier than the VL.73 tibial tract itself, or formation of a painful bursa between the This is mainly achieved during weight-bearing activities. It has band and the epicondyle.125,126

724 Disorders of the contractile structures C H A P T E R 5 4

origin of the gastrocnemius, a sprained posterior cruciate liga- ment or a lesion of the upper tibiofibular joint.

Hamstring strains

The hamstrings have a double function. They not only extend the thigh and flex the knee (concentric function), but also antagonize the quadriceps during knee extension in running (eccentric function). It is probable that a sudden change from stabilizing activity to an active function is the main reason for a hamstring strain.133–135 Lesions of the hamstrings are frequently seen in athletes, and rugby, American football and soccer players.136–138 Classi- cally, a strain occurs as a sprinter leaves the starting blocks or during a slide in soccer. The athlete feels a snap, immediately followed by pain and functional loss. In lesions of the muscle belly, straight leg raising is limited by pain because of muscle spasm. Prone-lying resisted knee flexion is painful. Resisted external or internal rotation can then distinguish between a biceps lesion or a lesion in the medial hamstrings. The short head of the biceps seems to be the most frequently strained.139,140 Fig 54.18 • A strained iliotibial band results from the band rubbing Sometimes there is a haematoma and the tender area is on the lateral epicondyle during repeated flexion–extension swollen.141 movements. Treatment While running, athletes notice increasing pain at the outer side of the knee, which forces them to stop. The pain is more An elastic wrap and an ice bag should be applied immediately intense when the foot comes in contact with the ground when after the incident. running downhill or during deceleration.127 In severe instances, Minor lesions require the same treatment as other muscular the pain may be so sharp that walking with a normal gait lesions. As soon as the patient is seen, whether this is on the becomes impossible. first day or after a week, the lesion is infiltrated with 50 mL Examination reveals no abnormality of the joint but some of procaine 0.5%. The patient lies prone, with the hip extended discomfort is experienced when extension and lateral rotation and the knee well flexed and supported by a pillow, so that the are carried out against resistance. Sometimes a painful arc is muscle belly is completely relaxed. The tender area is now found when the band slips over the lateral epicondyle at 30° identified, which may not be easy because the lesion may be of flexion. When the routine examination is negative, a simple deeply situated, especially when the short head of the biceps confirmatory test may be done. In 90° of flexion, pressure is is affected. applied at the iliotibial band over the lateral epicondyle; as the From the next day on, daily deep transverse friction is given, knee is gradually extended, the epicondylar area becomes together with isometric contractions, until the lesion is com- painful at about 30° of flexion.128 MRI may be useful in con- pletely cured. 129–131 firming the diagnosis. Technique: deep friction to the hamstrings The technique is very similar to the one used in quadriceps Treatment lesions but here the patient lies prone, with the hip extended Preventive measures include avoidance of excessive distance and the knee passively flexed to 90°. This position produces and hill running and a reduction in length of stride. complete relaxation of the muscle belly. The therapist sits or In most cases, 2–3 infiltrations with triamcinolone, deeply stands level with the patient’s limb. The fingers of one hand, between band and epicondyle, are successful.132 perhaps reinforced by the other hand, are placed deep to the Partial resection is advised in persistent lesions. affected part of the belly. The thumbs are positioned laterally on the femur and used as a fulcrum. An extension movement at the wrists moves the flexed fingers upwards and pulls on the Flexor mechanism fibres, which are felt to slip under the fingers (Fig. 54.19). The effect of deep friction can be increased somewhat by a rota- When resisted flexion of the knee causes pain in the posterior tional movement around the thumbs at the end of this move- aspect of the thigh, the fault is in the hamstrings. Resisted ment. As this treatment is extremely tiring, three periods of 5 internal and external rotation then differentiates between minutes’ friction over a total of 20 minutes is as much as is lesions of the medial hamstrings and of the biceps femoris. practicable. Should resisted flexion hurt at the knee, other possibilities After friction, electric or active isometric contractions arise. These are a strained popliteus muscle, tendinitis at either should be given for about 10 minutes. The purpose is to expand

725 The Knee the muscle transversely as much as possible, without strain on after clinical cure is established. Return to sport should be the healing fibres. This prevents intramuscular adhesions, often progressive, and special care should be taken to ‘warm up’ responsible for recurrent or chronic strains of the hamstrings.142 adequately. The possibility of recurrence is considerable if the patient Prophylaxis should also include progressive strengthening goes back to athletics too soon.143 Therefore treatment should exercises and stretching before and after activity.144 continue with massage and electric contractions for a week Biceps tendinitis

This usually occurs as an overuse lesion in athletes. Pain devel- ops at the outer side of the knee. Functional examination is entirely negative, except that resisted flexion hurts at the outer side. Resisted external rotation is also painful. Tenderness is found at the biceps tendon, usually at the tenoperiosteal inser- tion at the head of the fibula.145,146 Treatment consists of deep transverse friction. Alternatively, an infiltration with 20 mg of triamcinolone can be used but this is only effective if the lesion occurs at the insertion. Technique: friction to the biceps tendon The patient lies prone with the knee fully outstretched. The physiotherapist stands at the opposite side, level with the knee. The head of the fibula is easily identified. The index finger is placed on the tendon at the level of the lesion. Counterpres- sure is exerted with the thumb placed at the medial side of the knee (Fig. 54.20). Massage is now given using small, alter- nating extension and flexion movements at the wrist, while the thumb is kept still. Twenty minutes, three times a week for 3–6 weeks, may be required.

Lesions of the upper tibiofibular joint

Dislocations or fractures may occur after violent twists or direct blows, as when a rider’s knee is caught between a tree and the horse, for example.147 It is clear that the examiner must be especially alert for these injuries because they can lead Fig 54.19 • Deep friction to the hamstrings. to peroneal nerve palsy.

Fig 54.20 • Massage of the biceps tendon.

726 Disorders of the contractile structures C H A P T E R 5 4

1

(b) 3 (a)

2

Fig 54.21 • Resisted flexion at a right angle (a) and in full extension (b) differentiates between a lesion of the upper tibiofibular joint and the biceps tendon.

A sprain of the upper tibiofibular ligament can develop after trauma to the ankle joint or as the result of repetitive strains.148 Fig 54.22 • Anatomy of the lateral aspect of the knee: 1, lateral The findings on clinical examination are the same as in collateral ligament; 2, biceps tendon; 3a, popliteus muscle; biceps tendinitis. Because contraction of the biceps pulls the 3b, popliteus tendon. fibula backwards on the tibia, resisted flexion and resisted external rotation hurt at the outer side of the knee (Fig. The popliteus tendon originates from the lateral femoral 54.21a). However, when the biceps tendon is examined for condyle. It passes deeply to the lateral collateral ligament, tenderness, none is found. Resisted flexion in almost full exten- which it separates from the lateral meniscus.149 The tendon sion is also painless, because the fibular head is now pulling also attaches partly to the lateral meniscus.150,151 The muscle upwards instead of backwards and stress is no longer imposed belly inserts with a broad and short tendon at the posterior on the tibiofibular ligaments (Fig. 54.21b). Also, passive back- aspect of the tibia, in the popliteal fossa. Although the muscle wards movement of the fibular head elicits pain and the ante- is a flexor and internal rotator of the leg, its main function is rior tibiofibular ligament is tender to the touch. to prevent a sliding forwards of the lateral femoral condyle on Treatment is infiltration of the tender structure. One or two the fixed tibia during the stance phase in walking or running, infiltrations with 20 mg of triamcinolone solution usually especially in running downhill or descending stairs.152–154 This obtain permanent cure. makes the popliteus an important active stabilizer of the lateral and posterolateral aspect of the knee joint and explains the Lesions of the pes anserinus frequency of popliteal lesions in long-distance runners and downhill skiers. The prevention of forward sliding is also a These lesions are rare but are brought to mind if resisted flexion function of the posterior cruciate ligament (passive stabilizer), and internal rotation hurt at the inner side of the knee. Palpa- and a strained popliteus muscle can closely simulate a ligamen- tion usually reveals a tender spot at the insertion of the semi- tous strain of the posterior cruciate. Only a careful functional membranosus. Deep transverse friction clears the symptoms. examination differentiates the two lesions.155 It is important to remember that part of the semimem- Localization of the pain and palpation for tenderness further branosus inserts through the posterior oblique ligament at the reveal that the lesion lies at the tendon or in the muscle posterior border of the medial meniscus. In lesions of the belly.156,157 posterior horn, pain on resisted flexion can therefore compli- cate the clinical picture. Treatment Strained popliteus muscle Tendinous lesions respond very well to one or two infiltrations with 10 mg of triamcinolone. Should resisted flexion and internal rotation hurt at the lateral Alternatively, deep friction can be tried, to both the origin or posterolateral aspect of the knee, the popliteus tendon or and the body of the tendon, although the position of the muscle is suspected (Fig. 54.22). affected structure makes access for the palpating finger very

727 The Knee

Fig 54.24 • Deep friction to the popliteus muscle.

Resisted flexion painful in 90°

Painless in almost Posterior cruciate full extension Upper tibiofibular joint

Resisted internal Medial hamstrings rotation Pes anserinus (Medial meniscus?) Popliteus muscle

Resisted external Biceps muscle rotation Biceps tendon Upper tibiofibular joint

Rising on tiptoes Origin of gastrocnemius

Fig 54.23 • Infiltration of the popliteus tendon. Fig 54.25 • Differential diagnosis of resisted knee flexion.

difficult. Lesions of the muscle belly respond only to deep ligament until it reaches bone (Fig. 54.23). A series of droplets friction. is then injected at different areas, but only when the tip of the needle is felt to touch bone. Technique: infiltration of the popliteus tendon If the body of the tendon is tender, the injection should be The patient lies supine, with the knee flexed to 90°. The made around the tendon and not in the tendon itself. tendon is identified by careful palpation of the lateral condyle. At the most prominent aspect, two small bony projections Technique: deep friction to the popliteus muscle can be palpated, with a groove running vertically downwards The patient adopts a prone position, with the knee slightly between them. In this groove, the origin of the popliteus bent. The physiotherapist stands lateral to the patient’s leg. tendon can easily be palpated and followed until it disappears One thumb, reinforced by the other, is placed on the affected under the lateral collateral ligament. If the origin is tender, spot, parallel to the muscular fibres (Fig. 54.24). Deep trans- 1 mL of triamcinolone should be infiltrated with the usual verse friction is now given, by a supination movement of both technique: the needle is brought in through capsule and arms, which makes the thumbs roll transversely over the

728 Disorders of the contractile structures C H A P T E R 5 4 muscle fibres. The direction of the movement is cranial and palpation, the tender area is infiltrated with triamcinolone; this medial. usually gives a good result. The differential diagnosis of resisted knee flexion is sum- Lesions of the gastrocnemius marized in Figure 54.25.

Tendinous lesions at the origin of the gastrocnemii are very uncommon. We have only seen this lesion in cyclists. Diagnosis becomes obvious when not only resisted flexion but also Access the complete reference list online at rising on tiptoes hurts at the back of the knee. After careful www.orthopaedicmedicineonline.com

729 Disorders of the contractile structures C H A P T E R 5 4

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