17 Knee and Thigh Overuse Tendinopathy Barry P. Boden As the participation in athletic activities increases around border of the patella just deep to the remaining three the world, so does the frequency of tendinopathies. tendons. While the vastus intermedius courses parallel to the femur, the line of action in reference to the femur is • The etiology of most tendon injuries is related to re- 15 to 18 degrees for the vastus medialis longus, 55 to 70 petitive mechanical overload with the development of degrees for the vastus medialis obliquus, and 20 to 45 degenerative intratendinous lesions. degrees for the vastus lateralis [3]. • Nonoperative management consisting of activity Imaging techniques for evaluating the quadriceps restriction, nonsteroidal anti-inflammatory medica- tendon include radiography, ultrasonography, and MR tions, correction of external factors such as overtrain- imaging. MRI of normal quadriceps tendons reveals a ing, and physical therapy is successful in the majority laminated appearance with 3 (56%), 2 (30%), or 4 (6%) of acute tendinosis injuries. layers [4]. • Surgery is necessary for most complete tendon rup- tures, and may be considered for partial ruptures and in chronic tendinopathy patients who fail a 3 to 6 Quadriceps Tendinopathy month course of non-operative management. Quadriceps tendinopathy is much less frequent than patellar tendinopathy in athletes. This may be related to Quadriceps Tendon the superior strength, mechanical advantage, or vascular- ity of the quadriceps tendon. In adolescent athletes, avul- Anatomy sion injuries of the proximal patellar apophysis are more common than tendinopathy of the quadriceps mechanism The quadriceps tendon connects the four extensor [5]. Patients with quadriceps tendinopathy complain of muscles of the anterior thigh, the rectus femoris, the pain at the proximal pole of the patella. The pain is vastus intermedius, the vastus medialis, and the vastus lat- typically insidious, and often associated with a recent eralis to the patella. The tendon inserts on the proximal increase in jumping, climbing, kicking, or running. pole of the patella and continues distally as a tendi- Physical examination reveals tenderness over the supe- nous expansion over the anterior patella to merge with rior pole of the patella and discomfort with resistance to the patella tendon. Most of the fibers anterior to the extension with the knee hyperflexed. Patients should be patella are a continuation of the rectus femoris tendon evaluated for any malalignment entities, although no def- [1]. inite scientific evidence exists on a cause-and-effect rela- The rectus femoris and vastus intermedius lie centrally tionship between factors such as femoral anteversion, and parallel to the femur with the rectus femoris being increased Q angle, and tibial torsion and quadriceps the more superficial muscle. The vastus medialis consists tendinopathy. Quadriceps strength and hamstring flexi- of two muscle groups based on their orientation to the bility should also be assessed. In young athletes with patella. The vastus medialis obliquus fibers are oriented quadriceps strains, plain radiographs are usually normal. obliquely and attach more distally to the patella than the However, in older individuals with quadriceps tendinopa- vastus medialis longus [1]. The vastus lateralis muscle thy, degenerative changes such as calcification in the fibers insert on the superolateral patella more proximally tendon, or spur formation at the superior pole of the than the vastus medialis [1]. The tendinous fibers of the patella may be present.When extension strength is main- vastus intermedius insert directly into the superior tained, an MRI is rarely necessary but may demonstrate 158 17. Knee and Thigh Overuse Tendinopathy 159 degenerative changes at the insertion of the tendon (see Eccentric training aims to strengthen the tendon so Figure 17-1). that it can withstand higher stresses. The program Nonoperative management is successful in the vast involves static stretching both before and after the exer- majority of patients with quadriceps tendinosis. This con- cises. Eccentric exercises are performed in 3 sets of 10 sists of activity modification, anti-inflammatory medica- repetitions. With time, the speed of contractions is tions, and physical therapy. Once the pain subsides, increased. Each week the weight applied is increased and therapy should concentrate on quadriceps strengthening the cycle is repeated. Most cases resolve by 2 to 3 weeks. exercises and increasing hamstring flexibility. Strength- Only rarely is surgical intervention necessary. Indications ening exercises should focus on eccentric training of the include extensive tendinopathy in symptomatic patients muscle-tendon complex [6,7]. The proposed advantages who have failed a 3- to 6-month trial of nonoperative of eccentric exercises are based on 3 principles: management. Surgical principles include debridement of degenerative, diseased tissue, and promotion of healing 1. Length: By increasing the resting length of the by stimulating a vascular response either by longitudinal muscle-tendon unit, the strain within the complex is tenotomy and/or needling. reduced. 2. Load: Progressively increasing the load to the myotendon unit results in increased tensile strength. Partial Tendon Ruptures 3. Speed of contraction: Increasing the speed of con- Partial ruptures of the quadriceps tendon are rare, and traction also enhances the force capacity of the muscle require a high index of suspicion and a thorough exami- tendon complex [6]. Maximum eccentric contractions can nation for diagnosis [9,10]. Patients present with pain in generate 20% to 30% higher forces than isometric or the region of the quadriceps tendon, and weakness of concentric contraction [8]. Therefore, the tendon is knee extension. Often a history of a preexisting quadri- placed in an anabolic state instead of a catabolic state, ceps injury can be elicited, followed by a traumatic knee which is induced by immobilization or corticosteroid injury during athletic activity.Typically, the patient is able injections. to participate in sports with a dramatic drop in perfor- mance. If the vastus intermedius tendon is detached, which is often the case, there may be no deformity on examination. The key finding on physical examination is weakness of extension. The ability to extend the knee from a flexed position does not exclude a partial quadri- ceps rupture: Extension strength from a flexed position needs to be compared with the contralateral side. Although strength measurement tests may be helpful in documenting the extension deficit, there is a risk of com- pleting the tear with maximum resistance. Plain films are usually normal, but may demonstrate degenerative cal- cific changes within the tendon. MRI is the best diagnos- tic test for identifying the location and extent of the injury. There is a paucity of literature on the management of partial quadriceps tendon ruptures. For tears involving greater than 50% of the quadriceps tendon or tears diag- nosed late, the author prefers surgical repair. When the diagnosis is made acutely, the tear involves less than 50% of the tendon, and there is no tendon retraction, nonop- erative management with 6 to 8 weeks of brace immobi- lization may be considered. As healing progresses, the amount of knee flexion allowed by the brace may be increased. The author has seen this injury only as a ter- tiary referral, when the injury was chronic and the tendon retracted. In these cases, surgical repair of the partially torn tendon is recommended. Surgical repair involves a longitudinal incision over the quadriceps tendon. The Figure 17-1. MRI scan of a patient with quadriceps rectus femoris tendon is split, without being detached, to tendinopathy. (Courtesy of Wayne B. Leadbetter.) gain access to the vastus intermedius tendon. A Krackow 160 B.P. Boden stitch using nonabsorbable sutures is passed through the aminar tendon complex. The anterior half of the superior vastus intermedius tendon and any detached tendons. pole of the patella is debrided and abraded down to The attachment site on the anterior half of the superior bleeding bone to stimulate healing. The tendon is then patella is abraded to bleeding bone using a curette and/or reattached to the patella through drill holes or bone bur. The tendon is then sutured to the patella through anchors. Any rents in the extensor retinaculum should be drill holes or with bone anchors. repaired. In chronic cases, when the tendon has significantly Complete Tendon Rupture shortened or the tissue is tenuous, several techniques are available to strengthen the repair. If the tendon can be Healthy tendons do not rupture [11,12], and preexisting apposed to the bone but the tissue is weak, the repair may degenerative changes or systemic illness must be present. be reinforced by a flap or turndown of healthy proximal Degenerative changes occur as a result of prior low-grade quadriceps tendon or augmented with a semitendinosus microtears from activity. As the tendon heals from mild tendon [16]. If the quadriceps has shortened and cannot insults, it develops degenerative, not inflammatory, be apposed to the patella, a lengthening procedure with lesions. Histologic analysis of surgical specimens reveals augmentation is required. Codivilla described a length- a disorganized matrix, increased fibroblasts and vascu- ening procedure in which an inverted V is cut through the larity, and occasionally fatty, mucoid, or hyaline features full thickness of the