Search tips
Search criteria 


Logo of jathtrainLink to Publisher's site
J Athl Train. 2001 Apr-Jun; 36(2): 174–181.
PMCID: PMC155530

Recalcitrant Infrapatellar Tendinitis and Surgical Outcome in a Collegiate Basketball Player: A Case Report



To present the history, surgery, rehabilitation management, and eventual functional and surgical outcomes of a collegiate basketball player with recalcitrant jumper's knee.


A 21-year-old, male collegiate basketball player had a 2-year history of anterior knee pain.

Differential Diagnosis:

Injuries that often mimic symptoms of infrapatellar tendinitis include infrapatellar fat pad irritation, Hoffa fat pad disease, patellofemoral joint dysfunction, mucoid degeneration of the infrapatellar tendon, and, in preadolescents and adolescents, Sinding-Larsen-Johannsson disease.


After conservative treatment failed to improve his symptoms, the athlete underwent surgical excision of infrapatellar fibrous scar tissue and repair of the infrapatellar tendon.


This patient's case was unique in 3 distinct ways: (1) outcome surveys helped me to understand how this injury affected various aspects of this patient's life and how he viewed himself as he progressed through rehabilitation; (2) a modified functional test was used to help determine whether the athlete was ready to return to sport; and (3) the athlete progressed rapidly through rehabilitation and returned to competitive athletics in 3 months.


This patient was able to return to sport without functional limitations. The surgical outcome was also considered excellent.

Keywords: jumper's knee, tendinitis, tendinosis, rehabilitation

Patellar tendinitis, often referred to as jumper's knee, is a relatively common overuse injury often experienced by basketball, volleyball, distance running, long jumping, mountain climbing, figure skating, and tennis athletes.13 However, the pathologic condition is defined as an “insertional tendinopathy”4 that can occur at the superior or inferior patellar pole or at the tibial tubercle.5 Common symptoms related to this condition include pain, aching, and swelling at the inferior pole of the patella and weakness around the knee, with various degrees of quadriceps atrophy.3 In 1973, Blazina et al6 developed a classification of jumper's knee based on pain and functional limitations (Table (Table11).

Table 1
Classification of Jumper's Knee Developed by Blazina et al6*

Stages 1 and 2 usually respond well to conservative intervention involving therapeutic exercise, ice, ultrasound, cross-friction massage, and rest.1,3 Treatment of patients in stage 3 often includes a period of prolonged rest, reducing the number and frequency of playing sessions,1,3 and localized corticosteroid injection. Yet continuous overuse of the patellar tendon may lead to pain that is chronic and recalcitrant in nature.7 Surgery may be necessary for patients with stage 3 jumper's knee that has failed to heal.2,7,8 Colosimo and Bassett5 maintained that surgical intervention is the only treatment modality that can offer gratifying long-standing results in competitive athletes for whom long periods of inactivity are impractical.


Other conditions that may present with symptoms similar to those of infrapatellar tendinitis include injury to the infrapatellar fat pad, Hoffa disease, patellofemoral joint dysfunction, mucoid degeneration of the infrapatellar tendon, and, in adolescents and preadolescents, Sinding-Larsen-Johansson disease. With fat pad irritation, passive knee extension causes compression of the pad and usually elicits pain. The fat pad can also be “unloaded” by palpating the medial and lateral sides of the inferior pole and lifting the fat pad in a superior direction as the knee is passively extended. This generally reduces the patient's symptoms if the fat pad is irritated. Chronic inflammation of the fat pad can lead to Hoffa disease, a fibrosis of the infrapatellar fat pad.9 Diagnostic tests and clinical examination help to determine the diagnosis for patellofemoral dysfunction. However, patellofemoral dysfunction may also predispose the athlete to patellar tendinitis.3 Mucoid degeneration should be considered, particularly in patients who have experienced trauma, such as a direct blow to the tendon area.10 Magnetic resonance imaging or computed tomography can also be performed to confirm the diagnosis.10 Lastly, in Sinding-Larsen-Johansson disease, stresses are concentrated at the growth plates. Stress at the inferior pole of the patella leads to a traction epiphysitis and eventual fragmentation.5


Ferretti4 examined intrinsic and extrinsic factors that eventually led to jumper's knee and its progression. The intrinsic factors examined were sex, alignment of the knee and extensor mechanism, patellar position, characteristics of the tibial tuberosity, rotation of the femur and tibia, flexion contracture of the knee, degree of constitutional instability, characteristics of the foot, and morphotype. The extrinsic factors examined were number and frequency of training sessions, years of play, type of training, and playing and training surfaces. Hard playing surfaces and increased frequency of training sessions were the only factors that correlated positively with the incidence of jumper's knee. No correlation was noted between malalignment of the extensor mechanism or biomechanical derangement and the incidence of jumper's knee. Ferretti4 concluded that the mechanical properties of the tendon (resistance, elasticity, and extensibility) at the bone-tendon junctions were the most significant etiologic intrinsic factors.

Kujala et al11 agreed that the most important etiologic factors that contribute to jumper's knee were microruptures caused by jumping on hard surfaces. They also described significant correlations between leg-length inequalities and patella alta as possible predisposing factors to patellar apicitis (jumper's knee).

Almekinders and Temple12 reviewed articles in which training errors, inappropriate shoe wear, and anatomical predisposition that resulted from inflexibility, weakness, or malposition were described as playing a role in the etiology of chronic tendon injuries. However, many of the articles lacked a control group. They noted that most studies, including the one by Kujala et al,11 were retrospective and difficult to interpret.

My purpose is to present the case report of a collegiate basketball player with recalcitrant infrapatellar tendinitis, his clinical and surgical courses of treatment, and his eventual outcome. Proper use of the terms tendinitis and tendinosis will also be explored.


A 21-year-old, male collegiate basketball player, referred by a local orthopaedic surgeon, presented to our clinic with a 2-year chief complaint of right anterior knee pain and a recent diagnosis of recalcitrant jumper's knee. The athlete was evaluated by a certified athletic trainer at our facility, who concurred with the diagnosis of infrapatellar tendinitis after taking a thorough history of the athlete's complaints and ruling out the previously described knee conditions. The athletic trainer noted right quadriceps atrophy when compared bilaterally. Assessment of the athlete's active range of motion revealed full flexion without pain and full passive extension. With a straight-leg raise, a 5° to 10° lag was present and accompanied by pain. Formal manual muscle testing was not performed because the athlete's knee was inflamed. With palpation at the inferior pole of the patella, the patient had focal tenderness and visible thickening, about the size of a quarter and raised approximately 0.635 cm (¼ in), at the inferior pole of the patella. Results of x-ray films of the knee were unremarkable. A magnetic resonance imaging scan of the knee was not obtained. Additional subjective information was gathered via 3 outcome questionnaires: Cincinnati Knee Rating Scale,13 Quality of Life Questionnaire,14 and Patellofemoral Knee Pain Survey.15

The Cincinnati Knee Rating Scale is used to assess overall function of the patient's knees at the present time, including pain, swelling, giving way, overall activity level, walking, stairs, running activity, and jumping and twisting activities. The athlete was able to perform vigorous activities but at a lower performance level, had slight or mild problems with walking, had slight or mild problems with stairs, and had moderate problems with running 1.6 to 3.2 km (1 to 2 miles). The Quality of Life Questionnaire was used to assess the ways in which the athlete's injury had affected various aspects of his life. Each of the 5 parts includes a visual analog scale; the subject is asked to place a slash on a line, which ranges from 0 to 100. The questionnaire's 5 parts address symptoms and physical concerns, work-related concerns, recreational activities and sports participation or competition, lifestyle, and social and emotional concerns. In this questionnaire, the patient revealed that he experienced close to severe pain with prolonged activity (longer than ½ hour), moderate giving-out episodes, and an extremely weak knee (Table (Table2).2). He also reported difficulty squatting and going “full out” with activity and significant limitations with sudden twisting or pivoting motions and changes in direction. He was concerned about his knee getting worse and his competitive needs. The athlete was aware of his knee problem most of the time and was apprehensive with activity.

Table 2
Preoperative and Postoperative (3 and 14 Months) Results on Quality of Life Questionnaire14

The Patellofemoral Knee Pain Survey was also used to assess symptoms and overall function of the patient's knees. The patient had pain ascending and descending stairs, with the initiation of running and jumping, swelling in the evening, occasional painful movement of his kneecap in sporting activities, and the belief that motion and muscle mass were lost in the painful leg.

The patient's Cincinnati Knee Rating Scale and Patellofemoral Knee Pain Survey scores were 57/100 and 58/100, respectively. The preoperative Quality of Life Questionnaire scores were also calculated. After the evaluation, it was obvious that the patient could be categorized as having stage 3 infrapatellar tendinitis. His goal at this time was to finish the current season and be healthy to start playing in the end of the summer league program, the following (his junior) year, to prepare himself for conditioning, which started in mid September.

Conservative treatment was initiated, consisting of phonophoresis (0.4% dexamethasone and 0.1% lidocaine mixed in 0.47 L [16 oz] of ultrasound gel for 5 minutes at 3 MHz at 1.0 W/cm2), iontophoresis (dexamethasone at 40 mA/min with intensity as tolerated), ice with electric stimulation, and quadriceps and vastus medialis obliquus (VMO) strengthening. Quadriceps exercises included closed-chain single- and double-leg extensions on a leg machine (resistance was increased or decreased using rubber cords), weights on a leg press, terminal knee extensions on a multiple-hip exercise machine, and walking backward on a treadmill with a 5% grade. For the closed-chain double-leg extensions, the athlete squeezed a ball between his legs in an attempt to challenge the VMO. With the closed-chain single-leg extensions, a band was placed around the thigh and resistance was applied medially as the patient moved the leg into extension. Generally, the patient started with 3 sets of 10 repetitions and progressed to 3 sets of 15 repetitions. If he completed 3 sets of 15 repetitions without pain or difficulty, the resistance was increased and the repetitions decreased. The patient tolerated these exercises well and denied any increase in symptoms or pain with the strengthening activities.

Squeezing a ball with the double-leg extensions and the varus force applied with the single-leg extensions were selected to help recruit VMO firing during the exercises. The athlete attempted eccentric exercises to increase the tensile strength of the tissue, but he was unable to tolerate these exercises during his rehabilitation.

Stretching of the quadriceps, iliotibial band, hamstrings, gastrocnemius, and soleus was initiated prophylactically, and the athlete took nonsteroidal anti-inflammatory medication. He was seen by the athletic trainer in the clinic for 20 visits throughout 5 months and pursued a concurrent home exercise program. When the athlete was unable to travel to the clinic, the home exercise program was emphasized. Playing time was decreased, but there was no period of absolute rest.

After 5 months of conservative treatment, the patient returned to the orthopaedic surgeon. At this time, the patient was diagnosed as having recalcitrant jumper's knee and injected, in a peritendinous fashion, with a mixture of bupivicaine hydrochloride and betamethasone sodium phosphate. The patient was encouraged to continue with his rehabilitation and follow up with the surgeon in 1 month. If adequate progress was not made, an infrapatellar tendon debridement at the insertion of the patella would be considered. Conservative rehabilitation achieved limited success, and keeping the athlete's goal in mind, surgery was scheduled 1 month later, in mid April 1999.


The patient underwent excision of infrapatellar fibrous scar and repair of the infrapatellar tendon. During the surgery, the surgeon noted a small, partial tear of the infrapatellar tendon insertion at the inferior pole of the patella. This was debrided and rasped back to a bleeding bony edge. The patellar tendon tissue contained grayish-appearing hypertrophic scar tissue, which was also debrided back to a stable margin.

Postoperative Evaluation and Treatment

The athlete returned to the clinic the day after surgery in a straight-leg immobilizer. Weight bearing was permitted as tolerated. Modalities were applied to control effusion, and the patient returned 1 week later for a formal evaluation. The initial week of “relative rest” allowed the wound and tendon to recover from the surgery.7 Icing of the knee was emphasized daily along with heel slides and quadriceps setting. With the heel slides, the athlete was instructed not to bend his knee beyond his natural tissue tension. At the formal evaluation 1 week later, the patient complained of pain around his incision and stiffness with knee flexion. Objectively, quadriceps strength was graded 3−/5, passive knee extension was 0°, and active knee flexion was measured at 45°. The patient had moderate swelling in the patellar tendon, mild joint effusion, and a 10° extension lag when a straight-leg raise was attempted. Modalities (ice and electric stimulation) were used to control inflammation, and a pain-free exercise program was initiated.


Early Phase

The patient's initial rehabilitation, 1 week after surgery, consisted mostly of range-of-motion exercises, including heel slides, treadmill walking forward and backward, and biking. Strength exercises consisted of quadriceps setting using biofeedback instrumentation, straight-leg raising, leg-extension machine (both legs and single leg) (Figure (Figure1),1), and multiple-hip machine (Figure (Figure2)2) for terminal knee extensions and hip adduction. Passive stretching was performed on the hamstrings. Ice with interferential current concluded each session.

Figure 1
Knee extension exercise on the Shuttle MVP (Shuttle Systems, Glacier, WA).
Figure 2
Terminal knee extension on a Cybex Multi-Hip Machine (Cybex International, Inc, Medway, MA).

The patient's therapy was placed on hold when he left for vacation after the initial 3 weeks of rehabilitation. Strict guidelines were given to the patient at this time, and a home exercise program of ice, gastrocnemius and hamstring stretches, heel slides, quadriceps setting, and straight-leg raising was emphasized. The patient's active knee flexion at this time was 125°.

Approximately 1 month later, the patient returned to our clinic. He reported feeling good, being compliant with his home exercise program, and refraining from running or playing basketball to this point. Quadriceps strength was 4+/5. The evaluation also revealed full active range of motion, no quadriceps lag with straight-leg raising, and the ability to squat without pain. Rehabilitation was resumed.

Intermediate and Advanced Phases

Strengthening; progressive resistive exercise; proprioceptive, agility, and aerobic conditioning; plyometrics and eccentric loading; and functional or sport-specific drills were emphasized in this phase. Stretches (hamstrings, gastrocnemius, and quadriceps) and cryotherapy were also continued. Again, a pain-free progression was the goal. The patient began treadmill running at 8 weeks after surgery and functional or sport-specific drills on the following day. The aim was for the athlete to begin playing the following week. At 9 weeks, he was cleared for limited playing time by the orthopaedic surgeon and permitted to play 10 minutes per game at the most. Playing time was progressed as tolerated. The athletic trainer continued to monitor the patient's response to increased playing time and supervised continued strengthening and neuromuscular activities in the clinic.

Functional Testing

At 10 weeks after surgery, a functional test was used to objectively assess the patient's right lower extremity function compared with the uninvolved leg. The functional test consisted of a single-leg hop test, triple hop test, lateral hop test for time, maximum-repetition leg press at body weight, and 1-repetition maximum on the leg press. (For the lateral hop test for time, the athlete stood to the side of a solid line and was asked to hop across the line, back and forth, for 15 seconds.) The number of hops was then compared bilaterally. Compared with the opposite leg, the patient scored in the 96th percentile for the single-leg hop test and lateral hop test for time and 100% on the other 3 tests. At 3 months after surgery, the patient was discharged by the athletic trainer but instructed to continue with the home exercise program.

Reevaluation of Questionnaires and Clinical Examination

At 3 and 14 months after surgery, the patient again completed the questionnaires. At 14 months, his scores escalated to 100/100 on the Cincinnati Knee Rating Scale and 98/100 on the Patellofemoral Knee Pain Survey. He denied any limitations in activity, walking, stairs, running, jumping, or twisting. Review of the Quality of Life Questionnaire at 14 months also revealed that the patient was much improved (Table (Table2);2); interestingly, the athlete's lowest rating and greatest concern was with the environmental conditions, which was in agreement with the findings of Ferretti.4

In addition to having the patient complete the questionnaires, I evaluated the surgical outcome using a modification of the criteria defined by Kelly et al16 (Table (Table3).3). The athlete had full, bilateral active range of motion. Girth measurements taken at the superior pole of the patella and at 5.08 cm (2 in) and 10.16 cm (4 in) above the superior pole were equal bilaterally. Based on these objective findings and subjective reports of no pain and return to sports, the surgical outcome was considered excellent.

Table 3
Classification of Functional and Clinical Results16*

At 27 months after surgery, the athlete denied any knee pain. He did, however, note increased power and his satisfaction with being able to participate in the triple and long jumps the year before. These were events that he had not been able to participate in since high school because of his infrapatellar tendinitis.


Management of patellar tendinitis can be a very tedious process for the athletic trainer or physical therapist. Prevention and education are important components; however, athletes, in their desire to compete, often play through the pain and refrain from alerting the health care professional to their symptoms. In the case of patellar tendinitis, the initial symptoms tend to get worse if they are overlooked or the patient is noncompliant with treatment. The use of the word tendinitis in cases of true tendinosis may also lead to underestimation of the natural history of this condition by coaches and athletes.17 Pathologic tendon conditions may occur before any symptoms are noticed.18 If symptoms do manifest, patients in stages 1 and 2 of Blazina et al's scale6 can usually be treated successfully with conservative treatment.1,3 However, current treatment methods may not change the natural history of chronic tendon injuries,12 and patients with early symptoms of pain may also take months to recover.18 In these early stages, the practice surface and training parameters, such as frequency, intensity, and duration, should be evaluated and adjusted immediately and appropriately once symptoms are experienced. A proper rehabilitation program and progression should then be initiated to return the athlete to competition. The use of eccentric strengthening speeds tenocyte metabolism,19 causes quadriceps muscle hypertrophy,20 improves muscle coordination,20 and increases tensile strength of the tendon.21 This patient attempted eccentric exercises before surgery but could not tolerate them due to the significantly inflamed tissue. Therefore, pain-free exercises were adopted. After surgery, however, he tolerated eccentric exercises, which then became an important component in his rehabilitation and ultimate return to sport.

Also before surgery, closed-chain single- and double-leg exercises were attempted to challenge the VMO. The rationale to incorporate hip adduction exercises with a quadriceps contraction stems from the large proportion of the oblique fibers of the vastus medialis from the adductor magnus.22 Research examining preferential activation of the VMO with hip adduction has been controversial. Hanten and Schulthies23 reported that electromyographic activity of the VMO was significantly greater than that of the vastus lateralis during isometric hip adduction. Hodges and Richardson24 also reported increased VMO activity compared with the vastus lateralis with the addition of hip adduction in the weight-bearing position and only with maximal hip adduction in non–weight bearing. However, more recently, other authors2527 demonstrated no preferential activation of the VMO with hip adduction. It is difficult to say whether the external force provided for the single-leg knee extension or the isometric squeezing of a ball with the double-leg knee extension increased the firing of the VMO in this athlete. However, based on the current literature, it seems unlikely that preferential activation of the VMO occurred. The focus, therefore, should have been on training the entire quadriceps. Although the athlete achieved gains in quadriceps hypertrophy and strength before surgery, he was unable to tolerate eccentric loads and, therefore, would have been unlikely to develop the tendon tensile strength required to meet the specific imposed demands of basketball and the long and triple jumps in track and field.

Corticosteroid injections are not recommended to curb the pain of infrapatellar tendinitis because they can have adverse affects on the tendon.9 Repeated injections can also lead to permanent tendon injury.3 Previous investigations of prospective placebo-controlled studies versus corticosteroid injections for chronic tendon problems failed to show differences at follow-up compared with oral nonsteroidal anti-inflammatory drugs (NSAIDs) or placebo.12 Although NSAIDs may help with pain relief, possible healing effects on the tendon have not been studied.12 Using NSAIDs may also mask early symptoms, potentially leading to further tendon damage.19 With stage 3 tendinitis, which is perhaps more appropriately termed tendinosis, the conservative pathway is not so successful. Current conservative treatment methods, such as those for stages 1 and 2, may not significantly alter the patient's now-chronic state. At this point, the histopathology should be the focus of treatment19 and possible surgery. If surgery is indicated, the use of procedures such as a lateral release or VMO advancement may be questionable based on Ferretti's epidemiologic findings.4

In this athlete, initial symptoms were ignored and not reported. As a consequence, a self-limiting, manageable acute or subacute injury progressed to a chronic injury that eventually required surgery. In essence, the tendinitis progressed to a tendinosis. Because these terms can be confusing, classifications for tendinopathies have been developed.19,28 Bonar's classification of tendinopathies has been considered the most reliable (Table (Table44).19

Table 4
Bonar's Modification of Clancy's Classification of Tendinopathies19*

The term tendinitis refers to symptomatic degeneration of the tendon along with an inflammatory response and vascular disruption.19,28 Tendinitis, unlike tendinosis, does not encompass histologic changes occurring in the tendon.28 The term tendinosis histologically refers to noninflammatory degeneration due to aging, microtrauma, and vascular compromise.19,28 Furthermore, noninflammatory collagen degeneration occurs along with fiber disorientation, hypocellularity, and scattered vascular ingrowth, with possible calcification and necrosis.19,28 Given the surgeon's observation of a small tear in the tendon and a gray hypertrophic region, it was obvious that the athlete's injury was not self-limiting and would not have resolved with further conservative treatment.

With an emphasis on a pain-free progression and a proper rehabilitation program after surgery, the patient progressed rapidly and returned to competitive activities in 3 months. This time frame was similar to that described by Popp et al7 and Scranton and Farrar10 but shorter than the time frame reported by Cook et al29 (7 to 12 months), who noted that returning to jumping sports prematurely may contribute to a poor outcome.29 However, the rehabilitation for the athletes in this retrospective study was not discussed, nor were the details of the surgical technique.

Although this case study represents a successful surgical outcome and rehabilitation of infrapatellar tendinosis, there appear to be many unanswered questions relating to the management and the efficacy of treatment of tendinitis and chronic tendon injury. Many times, the patient is told to rest and pursue conservative treatment. However, how long the patient should rest and continue with conservative care before undergoing surgery remains unclear. In the case of this athlete, conservative treatment was continued for 6 months. The athlete experienced an exacerbation of symptoms during the season and opted to have surgery toward the end of the season. For any athlete, it is difficult to determine when surgery is the preferred option over continued conservative treatment. Although more difficult to influence and assess, intrinsic factors, such as the vascularity of the affected area and the rate of tenocyte repair, should be considered. With tissue damage, estimates are 2 to 3 weeks for a tissue response to occur.30 If the rate of tenocyte repair can be estimated in the individual, it would then be helpful in developing a hypothesis to determine when the patient should start to develop a healing response. If the patient then demonstrates a failure to heal, perhaps other interventions, such as sonography, may be helpful, in correlation with the clinical examination, in determining the extent and severity of the patellar tendinosis.5,7

Lastly, a modified functional test was incorporated to help determine the patient's readiness to return to sport. The use of a functional test, such as the one used in this case report, does not appear to be a common practice in helping to determine when to return to sport after patellar tendon surgery. Some authors have reported a goal of returning to sport in 12 weeks7 after an eccentric strengthening program or 7 to 12 months after rehabilitation.29 However, no data pertaining to the athlete's strength, endurance, or readiness to return to sport were reported. An adaptable functional test can provide meaningful information regarding the athlete's actual readiness throughout the rehabilitation progression. The single-leg hop and triple hop tests for distance are reliable measures of lower extremity performance compared with the uninvolved leg.31,32 The lateral hop test helped to provide information regarding the athlete's ability to change direction quickly in the frontal plane and the athlete's overall comfort level when performing a multiple lateral hop task on the involved leg. The single-leg 1-repetition maximum on the leg press was performed to assess bilateral leg strength. The maximum number of repetitions at the athlete's body weight on the leg press was performed to assess muscle endurance. However, the reliability and validity of these last 3 tests have not been examined in the literature. Although these functional tests are often reserved for helping to determine the readiness of an athlete to return to sport after anterior cruciate ligament reconstruction, they were helpful in the decision-making process to return this athlete to sport, in conjunction with the athlete's self-reports of function via outcome questionnaires and objective measures.

My purpose in describing this case study was to present the outcome of surgery and rehabilitation of recalcitrant infrapatellar tendinitis in a collegiate basketball player. The rehabilitation presented was developed to meet the needs of the injured athlete with the resources available. I did not personally supervise the rehabilitation of this athlete and, thus, do not necessarily endorse all aspects of the program. It was, however, apparent that this program of rehabilitation concluded with the athlete's successful return to high-demand activities.


Patellar tendinitis is a progressive disease that results from repetitive microtrauma at the bone-tendon junction, particularly at the inferior pole of the patella. If symptoms are ignored, the tendinitis eventually progresses to a tendinosis, which may then require surgical intervention. Therefore, it is important for the athletic trainer and physical therapist to emphasize prevention to athletes, coaches, and parents. Further scientific examination relating to early intervention, progression of tendinitis into tendinopathy, efficacy of treatment, and rehabilitation by certified athletic trainers and physical therapists for all stages of tendon injury is clearly warranted. Applicability and usefulness of functional testing in patients with chronic tendinosis and patellar tendon surgery should be further explored as well.


I thank Craig Sechler, MS, ATC, for reviewing this manuscript.


1. Ferretti A, Puddu G, Mariani PP, Neri M. The natural history of jumper's knee: patellar or quadriceps tendonitis. Int Orthop. 1985;8:239–242. [PubMed]
2. Ferretti A, Ippolito E, Mariani P, Puddu G. Jumper's knee. Am J Sports Med. 1983;11:58–62. [PubMed]
3. McCue FC., III Jumper's knee. Available at: Accessed April 25, 1999.
4. Ferretti A. Epidemiology of jumper's knee. Sports Med. 1986;3:289–295. [PubMed]
5. Colosimo AJ, Bassett FH., III Jumper's knee: diagnosis and treatment. Orthop Rev. 1990;19:139–149. [PubMed]
6. Blazina ME, Kerlan RK, Jobe FW, Carter VS, Carlson JG. Jumper's knee. Orthop Clin North Am. 1973;4:665–678. [PubMed]
7. Popp JE, Yu JS, Kaeding CC. Recalcitrant patellar tendinitis: magnetic resonance imaging, histologic evaluation, and surgical treatment. Am J Sports Med. 1997;25:218–222. [PubMed]
8. Roels J, Martens M, Mulier JC, Burssens A. Patellar tendinitis (jumper's knee) Am J Sports Med. 1978;6:362–368. [PubMed]
9. Magalini SI, Magalini SC. Dictionary of Medical Syndromes. 4th ed. Philadelphia, PA: Lippincott-Raven Publishers; 1997.
10. Scranton PE, Farrar EL. Mucoid degeneration of the patellar ligament in athletes. J Bone Joint Surg Am. 1992;74:435–437. [PubMed]
11. Kujala UM, Osterman K, Kvist M, Aalto T, Friberg O. Factors predisposing to patellar chondroplasty and patellar apicitis in athletes. Int Orthop. 1986;10:195–200. [PubMed]
12. Almekinders LC, Temple JD. Etiology, diagnosis, and treatment of tendonitis: an analysis of the literature. Med Sci Sports Exerc. 1998;30:1183–1190. [PubMed]
13. Noyes FR, McGinniss GH, Mooar LA. Functional disability in the anterior cruciate insufficient knee syndrome: knee rating systems and projected risk factors in determining treatment. Sports Med. 1984;1:278–302. [PubMed]
14. Mohtadi N. Development and validation of the quality of life outcome measure (questionnaire) for chronic anterior cruciate ligament deficiency. Am J Sports Med. 1998;26:350–359. [PubMed]
15. Kujala UM, Jaakkola LH, Koskinen SK, Taimela S, Hurme M, Nelimarkka O. Scoring of patellofemoral disorders. Arthroscopy. 1993;9:159–163. [PubMed]
16. Kelly DW, Carter VS, Jobe FW, Kerlan RK. Patellar and quadriceps tendon ruptures: jumper's knee. Am J Sports Med. 1984;12:375–380. [PubMed]
17. Maffulli N, Khan KM, Puddu G. Overuse tendon conditions: time to change a confusing terminology. Arthroscopy. 1998;14:840–843. [PubMed]
18. Leadbetter WB. Cell-matrix response in tendon injury. Clin Sports Med. 1992;11:533–578. [PubMed]
19. Khan KM, Cook JL, Bonar F, Harcourt P, Astrom M. Histopathology of common tendinopathies: update and implications for clinical management. Sports Med. 1999;27:393–408. [PubMed]
20. Eifert-Mangine M, Brewster C, Wong M, et al. Patellar tendinitis in the recreational athlete. Orthopedics. 1992;15:1359–1366. [PubMed]
21. Stanish WD, Rubinovich RM, Curwin S. Eccentric exercise in chronic tendinitis. Clin Orthop. 1986;208:65–68. [PubMed]
22. Bose K, Kanagasuntheram R, Osman MBH. Vastus medialis oblique: an anatomical and physiologic study. Orthopedics. 1980;3:880–883. [PubMed]
23. Hanten WP, Schulthies SS. Exercise effect on electromyographic activity of the vastus medialis oblique and vastus lateralis muscles. Phys Ther. 1990;70:561–565. [PubMed]
24. Hodges PW, Richardson CA. The influence of isometric hip adduction on quadriceps femoris activity. Scand J Rehabil Med. 1993;25:57–62. [PubMed]
25. Zakaria D, Harburn KL, Kramer JF. Preferential activation of the vastus medialis oblique, vastus lateralis, and hip adductor muscles during isometric exercises in females. J Orthop Sports Phys Ther. 1997;26:23–28. [PubMed]
26. Laprade J, Culham E, Brouwer B. Comparison of five isometric exercises in the recruitment of the vastus medialis oblique in persons with and without patellofemoral pain syndrome. J Orthop Sports Phys Ther. 1998;27:197–204. [PubMed]
27. Karst GM, Jewett PD. Electromyographic analysis of exercises proposed for differential activation of medial and lateral quadriceps femoris muscle components. Phys Ther. 1993;73:286–299. [PubMed]
28. Clancy WG. Tendon trauma and overuse injuries. In: Leadbetter WB, Buckwalter JA, Gordon SL, editors. Sports-Induced Inflammation. Park Ridge, IL: American Academy of Orthopaedic Surgeons; 1990. pp. 609–618.
29. Cook JL, Khan KM, Harcourt PR, Grant M, Young DA, Bonar SF. A cross sectional study of 100 athletes with jumper's knee managed conservatively and surgically. Br J Sports Med. 1997;31:332–336. [PMC free article] [PubMed]
30. Jozsa L, Kannus P. Human Tendons: Anatomy, Physiology, and Pathology. Champaign, IL: Human Kinetics; 1997. pp. 4–95.
31. Petschnig R, Baron R, Albrecht M. The relationship between isokinetic quadriceps strength test and hop tests for distance and one-legged vertical jump test following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 1998;28:23–31. [PubMed]
32. Bolga LA, Keskula DR. Reliability of lower extremity functional performance tests. J Orthop Sports Phys Ther. 1997;26:138–142. [PubMed]

Articles from Journal of Athletic Training are provided here courtesy of National Athletic Trainers Association