Patellar Tendinosis

Focus On Patellar Tendinosis

Introduction ally an adaptive process secondary to impingement and com- ‘Jumper's knee’ or patellar tendinosis is a common condition pressive forces at approximately 60° of knee flexion rather than affecting athletes with an incidence in this subpopulation of 13% a degenerative or inflammatory process from tensile forces.11 to 20%.1,2 It is particularly prevalent in sports involving jumping and heavy landing, rapid acceleration or deceleration and kicking, Histopathology such as basketball, volleyball, soccer, tennis, long jump and high Alfredson et al used a microdialysis technique to show that there jump.1,2 It has a tendency to become chronic and, in elite athletes, were no inflammatory cells in patellar tendinosis but high levels the incidence of having to retire from their sport is as high as of the neurotransmitter glutamate, suggesting that this may be a 53%.3 By comparison, injury is known to be the main reason for source of the pain associated with patellar tendinosis.12 Several ending the careers of elite athletes in only 20% of cases.4 Long- studies have examined excised tissue in the region of the inser- term studies have also shown that symptoms can persist for many tion of the patellar tendon into the inferior pole of the patella. years although do not typically affect a patient's work or leisure The tendon is often expanded in this area with loss of demarca- activities once they have retired from elite sport.3,5 tion of the collagen bundles and an increase in mucoid degener- There are both intrinsic and extrinsic factors that are thought ation, intratendinous calcification, fibrinoid necrosis and to contribute to the development of jumper's knee. Extrinsic fac- features of tendinosis.5,13-15 Inflammatory cells are not typically tors include training frequency, intensity of training, playing sur- seen. The histological changes also include elevated high- faces that are hard, and footwear.1,2,5 Intrinsic factors include a molecular-weight proteoglycans and type III collagen which variety of physical parameters within the athlete themselves that Hamilton and Purdam further suggest is more consistent with are thought to contribute to the development of this condition, compressive loads and adaptive changes.11 such as patellar height, malalignment, limb length discrepancy, muscular imbalance or a combination of these.1 Most of the Classification studies suggesting that these parameters may be causative are Blazina et al16 proposed a classification for jumper's knee in six retrospective. A prospective two-year study of 138 students stages according to symptoms, which can be used to guide entering a sports programme found that the only significant treatment options; this has been modified by Roels et al as determining factor was muscular flexibility.1 Recently, patellar seen below.9 morphology has been thought to play a role with several authors suggesting that impingement of the inferior pole of the patella Table I. Classification for Jumper’s Knee16 on the dorsal fibres of the patellar tendon may be responsible.6 Stage 0 No pain Other studies have shown an elongation of the non-articular portion of the inferior pole which could also be causative, although Stage 1 Pain only after intense sports activity; no undue functional impairment this may be a traction or secondary phenomenon.7,8 Stage 2 Pain at the beginning and after sports activity; The traditional theory of patellar tendonitis was one of an still able to perform at a satisfactory level inflammatory process secondary to tensile forces.9 More Stage 3 Pain during sports activity; recently an impingement model of patellar tendonitis was pro- increasing difficulty in performing at a satisfactory posed by Johnson, Wakeley and Watt based primarily on the level location of the tendon lesion found on MRI studies.6 Other imag- Stage 4 Pain during sports activity; ing studies and histological retrieval specimens have also shown unable to participate in sport at a satisfactory level that the pathological tissue is limited to the dorsal fibres of the Stage 5 Pain during daily activity; unable to participate in sport at any level proximal insertion of the patellar tendon. Schmid et al performed MRI scans of knees in varying degrees of flexion and demonstrated that the angle between the patella and patellar tendon changed from 157° to 145° during flexion with a maxi- Imaging mum angulation between 50° and 70° of knee flexion.10 Both ultrasound and MRI have been described for the diagnosis Hamilton and Purdam proposed that patellar tendinosis is actu- of patellar tendinosis. Ultrasound has traditionally been used to

1 2 M. P. R. WILKINSON, F. S. HADDAD image tendons and reveals consistent findings in patellar return to sport. This can range from six to ten months.15,34,35 tendinitis.17 The tendon reveals an area of hypoechoic signal More recently, arthroscopic surgical procedures have been change and increased thickness corresponding to the area of described with good results and a more rapid return to func- clinical tenderness.5 Colour Doppler examination is a useful tion.27,35-37 At the time of arthroscopic surgery, different authors adjunct as it has been shown to identify vascularity and neoves- have described a simple excision of the distal patellar pole, or a sels in the area of structural change.18,19 MRI has also been tendinosis debridement, or both. These studies have all reported shown to identify a signal defect in the proximal patellar tendon success rates in terms of symptomatic improvement >85%. and increased thickness in the tendon.20-22 However, there is Coleman et al described a return to sports of only 46% in their some disagreement within MRI studies over what lesions repre- series.35 Two other studies showed a return to the previous level sent pathology or normal variants; asymptomatic patients can of sporting function of >85%29,37 and one did not report on also have reportedly unequivocal findings on MRI.23,24 this.36 Time to return to sport was reported as between two and six months in these studies. Management Patellar tendinosis is typically managed conservatively in the Summary early stages. Non-operative management includes activity Patellar tendinosis is a common condition that has proven diffi- restriction or modification, ice, anti-inflammatories, eccentric cult to explain in terms of its aetiology and the best way in which stretching, massage or taping. Bahr et al25 have performed one it should be managed. Understanding of this condition has of the few randomised controlled trials of operative versus con- evolved from models proposing inflammatory and degenerative servative management of patellar tendinosis. They found that tendinosis created by tensile forces to a concept of impingement both groups showed significant improvements over a twelve- and compressive forces resulting in neovascularisation of the month period although there was no statistical significance dorsal proximal pole of the patella tendon. Conservative man- between the two groups. A further, successful conservative agement should be employed in the early stages, including activ- measure is sclerosant injections under ultrasound guidance. ity modification and eccentric strength training. Sclerosing Alfredson et al26 published good clinical results in 12 out of 15 injections have also been proven successful. Surgery that is tendons. All patients were found to have evidence of neovascu- directed to either the tendon or the inferior pole of patella can larisation inside and outside the dorsal part of the proximal yield satisfactory results. Arthroscopic surgery appears to pro- patellar tendon on Doppler ultrasound and were treated with an vide results that are as good as open surgery, but with reduced injection of sclerosant under ultrasound guidance. Subsequent morbidity and a more rapid return of function. imaging showed a reduction or complete loss of the neovascu- Matthew PR Wilkinson, FRACS (Orth), Clinical Fellow UCLH larisation; this correlated with good outcomes over a four- to six- Fares S Haddad, FRCS (Orth), Consultant Orthopaedic Surgeon month period. Similar results have been seen with Achilles tend- Department of Orthopaedics, University College Hospital, London, UK 27,28 inopathy. Because of the long period of time needed to real- Email: [email protected] ise good results, a series of arthroscopically-treated cases was subsequently published.29 In this series of 15 patients, arthro- References scopic shaving of the dorsal tendon was performed and no addi- 1. Witvrouw E, Bellemans J, Lysens R, Danneeks L, Cambier D. Intrinsic risk factors for the development of patellar tendinitis in an athletic population; A two-year tional bony procedure unless there was an osteophyte on the prospective study. Am J Sports Med 2001;29:190-95. inferior pole. Patients were able to return to sport within two 2. Jarvinen M. Epidemiology of tendon injuries in sports. Clin Sports Med months in the majority of cases. 1992;11:493-504 There are multiple open surgical procedures for patellar tend- 3. Kettunen JA, Kvist M, Alanen E, Kujala UM. Long term prognosis for jumper's knee in male athletes: a prospective follow-up study. Am J Sports Med 2002;30:689-92. inosis described but the most common involves an open exci- 4. Kettunen JA, Kujala UM, Kaprio J. Lower limb function among former elite male sion of the diseased portion of the patellar tendon. Treatment of athletes. Am J Sports Med 2001;29:2-8. the paratenon greatly varies, as does post-operative immobilisa- 5. Cook JL, Khan KM, Harcourt PR, Grant M, Young DA, Bonar SF. A cross sec- tion. In addition, some surgeons have described drilling, debrid- tional study of 100 athletes with jumpers knee managed conservatively and surgi- cally. Br J Sports Med 1997;31:332-36. 30-32 ing or excising the distal pole of the patella. Kaeding, 6. Johnson DP, Wakeley CJ, Watt I. Magnetic resonance imaging of patellar tendo- Pedroza and Powers performed a recent systematic review of nitis. J Bone Joint Surg [Br] 1996;78-B:452-7. the literature concerning surgical treatment.33 They found nine 7. Blazina ME, Kerlan RK, Jobe FW, Carter VS, Carlson GJ. Jumper's knee. Orthop studies that met their inclusion criteria, giving a total of 312 ten- Clin North Am 1973;4:665-78. 8. Roels J, Martens M, Mulier JC, Burssens A. Patellar tendinitis (jumper’s knee). dons; eight of the studies reported >80% success with a variety Am J Sports Med 1978;6:362-368. of principally open techniques. However, success was not always 9. Leadbetter WB. Cell Matrix response in tendon injury. Clin Sports Med 1992;11:533-78. clearly defined while a return to high-level sports varied from 10. Schmid MR, Hodler J, Catherein P, et al. Is impingement the cause of jumper's 46% to 91%. The authors also found no difference with respect knee? Dynamic and static magnetic resonance imaging of patellar tendonitis in an open configuration system. Am J Sports Med 2002;30:388-95. to whether bony work was performed, the paratenon was closed, 11. Hamilton B, Purdam C. Patellar tendinosis as an adaptive process: a new hypothe- or whether the patient was immobilised after operation. sis. Br J Sports Med 2004;38:758-61. The greatest limitation to open surgical procedures appears 12. Alfredson H, Forsgren S, Thorsen K, Lorentzon R. In Vivo microdialysis amid not to be related to their success rates but the protracted post- immuno-histochemical analysis of tendon tissue demonstrated high amounts of free glutamate and glutamate NMDARI receptors, but no signs of inflammation, in operative course of immobilisation and the time needed to Jumper's knee. J Orthop Res 2001;19:881-86.

THE JOURNAL OF BONE AND JOINT SURGERY PATELLAR TENDINOSIS 3

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