Overuse Tendinosis, Not Tendinitis

Part 2: Applying the New Approach to Patellar Tendinopathy

Jill L. Cook, B App Sci, PT; Karim M. Khan, MD, PhD; Nicola Maffulli, MS, MD, PhD; Craig Purdam, Dip Phty, PT

THE PHYSICIAN AND SPORTSMEDICINE - VOL 28 - NO. 6 - JUNE 2000

In Brief: Patellar tendinopathy causes substantial morbidity in both professional and recreational athletes. The condition is most common in athletes of jumping sports such as basketball and volleyball, but it also occurs in soccer, track, and tennis athletes. The disorder arises most often from collagen breakdown rather than inflammation, a tendinosis rather than a tendinitis. Physicians must address the degenerative pathology underlying patellar tendinopathy because regimens that seek to minimize (nonexistent) inflammation would appear illogical. Suggestions for applying the 'tendinosis paradigm' to patellar tendinopathy management include conservative measures such as load reduction, strengthening exercises, and massage. Surgery should be considered only after a long-term and appropriate conservative regimen has failed.

Patellar tendinopathy causes morbidity in athletes and active patients alike. Both early and more recent histopathologic studies indicate that the condition previously known as "patellar tendinitis" is not, in fact, due to inflammation but is the result of collagen breakdown (1)—a condition known histopathologically as tendinosis (see "Tendinitis, Tendinosis, Tendinopathy—Why the Fuss?," below). The significance of differentiating between tendinosis and tendinitis has been reviewed previously (2-5) (see "Overuse Tendinosis, Not Tendinitis, Part 1: A New Paradigm for a Difficult Clinical Problem," May, page 38) and will not be covered in detail here.

Instead, we focus here on clinical application of the "new paradigm" with patellar tendinopathy as the example. To this end, performing a detailed clinical assessment and making the correct diagnosis in patients who present with activity-associated anterior knee pain are critical.

Clinical Assessment of Patellar Tendinopathy

History. The patient with patellar tendinopathy often plays basketball, volleyball, or another activity that involves jumping. Soccer, aerobics, and track athletes are also at risk. Men are affected more commonly than women. Knee pain may arise insidiously. Those patients who recall when the pain began report that it started during one heavy training session or, less commonly, from one specific jump. In addition, they often remember a specific activity that seemed to make the pain worse. Pain is usually well localized to a small area of the anterior knee region, and many patients have noticed tenderness at the inferior pole of the patella before they present for a medical examination.

Early in the course of patellar tendinopathy, the patient's knee pain and discomfort may ease completely while exercising. In this case, it is not uncommon for the player to disregard the injury and not seek treatment. With time and continued activity, however, pain worsens and limits sporting performance. Eventually, pain can develop during activities of daily living and can even be present at rest.

Physical examination. Patients with chronic symptoms may exhibit quadriceps wasting, most notably in the vastus medialis obliquus. Thigh circumference may be diminished, and calf muscle atrophy may or may not be apparent. Testing the functional strength of the quadriceps and calf muscles may be done by comparing the ease with which the patient can perform 15 one-legged step-downs. The athlete bends at the knee and then straightens again without letting the other foot touch the floor. Work capacity of the calf is assessed by asking the patient to do single-leg heel raises. Jumping athletes should be able to do at least 40 raises. It is important to monitor both the onset of fatigue and the quality of movement (eg, control, as measured by wobbling) because either can be affected in the symptomatic limb.

Palpation of the tendon attachment at the inferior pole of the patella has been the classic physical examination technique for detecting patellar tendinopathy. Clinicians should be aware that mild tenderness at this site is not unusual when the tendon is normal. Cook et al (6) found that a skilled clinician could reproducibly categorize tenderness as mild, moderate, or severe. Only moderate and severe tenderness was significantly associated with tendon abnormality as defined by ultrasonography. Thus, we suggest that mild patellar tendon tenderness should not be overinterpreted and may be a normal finding in active athletes (6). Pain can also be reproduced with the decline squat test (figure 1).

Differential diagnosis. Patellofemoral pain syndrome (PFS) is the main disorder in the differential diagnosis of gradual-onset anterior knee pain in athletes who participate in jumping activities (table 1). The clinical features of patellar tendinopathy are, however, generally distinctive (7) and some authors have suggested the diagnosis is straightforward (8). Our clinical impression is that this is true in about three fourths of the cases of patellar tendinopathy but that, in some cases, PFS and patellar tendinopathy may be difficult to differentiate, or the conditions may coexist.

TABLE 1. Investigation Plan in Three Common Presentations of Anterior Knee Pain
Classic Presentation of Jumper's Knee	Anterior Knee Pain Not Typical of Either Jumper's Knee or Patellofemoral Pain Syndrome (PFS)	Classic Presentation of PFS
High-risk sporting activity (eg, basketball, volleyball)	Sporting activity sometimes, but not classically, associated with patellar tendinopathy (eg, long-distance running)	Nonsporting or recreational, low-impact sporting activity
Good history of activity-related pain, rather well localized to inferior pole of the patella	History has elements of both patellar tendinopathy and PFS	Vague anterior knee pain, occurs at rest, not well localized
Moderate or severe tenderness on palpation at inferior pole of the patella	Mild tenderness at inferior pole of the patella or diffuse tenderness that includes the patellar facets or the fat pad	Minimal tenderness or tenderness of the patellar facets only
Diagnose patellar tendinopathy clinically—no investigation indicated; begin treatment of patellar tendinopathy	MRI or ultrasound to aid decision making. If imaging reveals characteristic features of patellar tendinopathy, treat accordingly. If normal, consider other causes (eg, PFS or very early patellar tendinopathy).	Diagnose PFS clinically—no investigation indicated; begin treatment of PFS

Caveats About Imaging in Patellar Tendinopathy

Ultrasonography and magnetic resonance imaging (MRI) provide excellent anatomic representation of tendons, but imaging does not predict prognosis or distinguish outcome. In the patellar tendon, increased signal on MRI (1,9-11) (figure 2A: not shown) and hypoechoic regions on ultrasonography (1,12,13) (figure 2B: not shown) reflect collagen degeneration (1). Unfortunately, identical appearances also exist in tendons of totally asymptomatic jumping athletes (figure 3: not shown) (13,14). Furthermore, a prospective imaging study (15) with longitudinal follow-up showed that the presence of an ultrasonographic abnormality in patellar tendons did not predict poor prognoses in very active elite basketball players. After tendon surgery, imaging cannot distinguish subjects who have good clinical outcome from those who have a poor outcome (figure 4: not shown) (16,17). Because imaging does not reflect function or predict prognosis (18) it must remain a supplemental aid to the history and physical examination. Table 1 shows our approach to imaging in cases of anterior knee pain in which patellar tendinopathy is part of the differential diagnosis.

Conservative Management

Numerous conservative treatments have been and are being used to treat patellar tendinopathy; however, few therapies have undergone randomized prospective, placebo-controlled trials, and such studies are urgently needed (19). Current evidence suggests that traditional treatment aimed at reversing the inflammation in "tendinitis" is largely ineffective. Other therapies may be useful for promoting healing in tendinosis.

Load reduction and relative rest. Many strategies are available to reduce the load on the patellar tendon without resorting to the unimaginative dictum "stop everything." In any case, complete immobilization of an injured tendon is contraindicated because the tensile load stimulates collagen production and directs its alignment. Relative rest for patients means that they may continue playing or training if elements of the activity (eg, jumping or sprinting) or total weekly training hours can be reduced.

Biomechanical correction. In jumping sports, forces generated in landing are substantially greater than those that produce the jump. Therefore, correcting biomechanics is an important component of management to improve the energy-absorbing capacity of the limb both at the affected musculoskeletal junction and at the hip and ankle. The ankle and calf are critical in absorbing the initial landing load, and any functional compromise of these structures increases the load transmitted to the knee (20). Studies estimate that about 40% of landing energy is transmitted proximally (21). Thus, the calf complex must function well to absorb a major portion of the load that would otherwise be transmitted proximally to the patellar tendon-quadriceps complex. Compared with flat-foot landing, forefoot landing generates lower ground reaction forces; if this technique is combined with a large range of hip or knee flexion, vertical ground reaction forces in landing can be reduced by a further 25% (22).

Biomechanical correction requires assessment of both anatomic and functional deficiencies. Anatomic variants that predispose to patellar tendinopathy are listed in table 2. Some anatomic abnormalities, such as pes planus, may be evident during static assessment, but others, such as excessively rapid pronation, may only be evident during dynamic evaluation. Thus, both static and dynamic assessment are required (23,24). Shoe orthoses are one method of correcting some biomechanical faults; other physicians (not the authors) recommend knee braces.

TABLE 2. Anatomic Characteristics Associated With Patellar Tendinopathy
Limb or Joint	Symptoms
Foot	Excessive range of pronation, excessively fast pronation (even within a normal range), pes planus, rigid cavus foot, poor dorsiflexion (eg, due to anterior impingement syndrome)
Knee	Hyper- or hypomobile patella leading to poor mechanism of patellofemoral movement, tight band between iliotibial band and patella
Thigh	Tight iliotibial band
Hip	Coxa vara, femoral anteversion

Biomechanical abnormalities can arise from functional as well as anatomic abnormality. Inflexibility of the quadriceps, hamstrings, iliotibial band, or calf have the potential to restrict range of motion at the knee and ankle and are likely to increase the load on the patellar tendon. Hamstring tightness (decreased sit and reach test) is associated with increased prevalence of ultrasonography-proven patellar tendinopathy in males (25). Weakness of the gluteal, lower abdominal, quadriceps, and calf muscles leads to fatigue-induced aberrant movement patterns that may alter forces acting on the knee. It is imperative that proximal and distal muscle groups be assessed in patients with chronic patellar tendinopathy (see "Strengthening: Putting Theory Into Practice," below).

Cryotherapy. Cryotherapy (eg, ice) may decrease the extravasation of blood and protein from new capillaries found in tendinosis (26). Cold also decreases the metabolic rate of tendon. Both mechanisms may promote healing of patellar tendinopathy.

Massage. Deep friction massage has been a time-honored treatment for tendinopathy (27), and recent investigations (28,29) at Ball State University found that soft-tissue mobilization increases fibroblast recruitment and promotes healing in rat tendons.

Although there have been few studies of massage (27), we believe this modality is essential for maintaining a compliant muscle during rehabilitation. It is essential that both the calf and quadriceps muscle are regularly massaged because strength programs will naturally cause muscle stiffness.

Ultrasound. Laboratory studies have shown that therapeutic ultrasound increased collagen synthesis in tissue culture (30) and increased tensile strength of tendon that had been surgically severed (31), but the modality had little effect on inflammation (32). Ultrasonography had no significant effect on rat patellar tendon healing (33), and there is no evidence in humans that such modalities are a cost-effective therapy for tendinosis. Furthermore, there is no consensus on the appropriate ultrasound dosage for tendinosis. Because the therapeutic range is unspecified, exceeding the optimal dose (if one exists) is a concern (34).

Anti-Inflammation Therapies

NSAIDs and corticosteroids. Therapies such as nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids have been used in the "tendinitis" model of tendon treatment because of their so-called "anti-inflammatory" role. But one study using a rat tendon model showed that neither ultrasound nor indomethacin had any effect on healing (33).

Corticosteroids have a direct impact on tendon tissue and can cause collagen necrosis (35). Reviews (36-38) show that no published studies have systematically evaluated corticosteroid injection in patellar tendinopathy, though two abstracts have been published. Employing ultrasound, one study showed a reduction in size of the abnormal tendon after injection (39), and the other showed that the reduction was correlated with a reduction in pain (40). The patellar tendon may be vulnerable to rupture for several weeks after the injection (36), so the clinician giving the injection must explain potential complications and take particular care to avoid intratendinous injection.

New inhibitors. One of us (NM) conducted a prospective, randomized trial in 116 athletes with patellar tendinopathy to assess the efficacy and tolerability of paratendinous injections of aprotinin, a polyvalent inhibitor of proteolytic enzymes (41). Athletes were randomly assigned to receive injections of either aprotinin, methylprednisolone acetate, or normal saline. At the 12-month follow-up, excellent or good results were seen in 72% of patients in the aprotinin group, 59% of the methylprednisolone acetate group, and 28% of the saline group. Poor results in these groups were 7%, 12%, and 25%, respectively. The role of proteolytic enzymes in degenerative conditions of the musculoskeletal system is still being elucidated; however, it appears that aprotinin does not exhibit the catabolic properties of corticosteroids but exerts a significant analgesic effect. Long-term studies are required to determine whether this effect is permanent.

Surgery for Patellar Tendinopathy

Variable outcomes. Patellar tendon surgery has a rather unpredictable outcome. A review of 23 papers found that for surgery the combined excellent and good results were between 46% and 100% (42). In the three studies that had more than 40 patients, authors reported combined excellent and good results of 91%, 82%, and 80% in series of 78, 80, and 138 subjects, respectively. The mean time for patients to return to preinjury level of sport varied from 4 months to greater than 9 months. A long-term study (43) of outcome in patients who underwent open patellar tenotomy for patellar tendinosis showed that only 54% were able to return to previous levels of sport activity. In two prospective studies (17,44) that evaluated time to return to sport, most subjects required more than 6 months, and often 9 months, to return to full sporting competition.

There is no consensus about the optimal surgical technique to use, with surgeons performing either a longitudinal or a transverse incision over the patellar tendon. Some surgeons excise the paratenon, while others suture it after having performed the longitudinal tenotomies and excision of the affected area. Still others repair the tendon with absorbable suture after the tenotomies (42).

New techniques. Recently, surgeons have tested ultrasound-guided multiple longitudinal tenotomy, a novel approach to patellar tendon surgery that is less invasive than broad debridement. In a well-controlled study, Testa et al (44) reported that 60% of patients had either an excellent or good result and a more rapid return to sport with the new technique than with surgery that employed the traditional methods. However, the authors recommend careful selection of patients because the new procedure seems to be more successful in patients who have tendinopathy of the main tendon body than in those who have the more classic lesion near the proximal pole of the patella.

Arthroscopic debridement of the posterior portion of the patellar tendon has also been described (figure 5) (43,45). In the only study (43) comparing arthroscopic treatment with traditional open patellar tenotomy, outcomes appeared similar. The study also revealed a trend to more rapid return to activity in the arthroscopically treated group, but the study lacked power to substantiate that arthroscopy yielded a better outcome than open tenotomy.

We recommend surgery only after a thorough, high-quality conservative program has failed. Surgeons must advise patients that while symptomatic benefit is very likely, return to sport at the previous level cannot be guaranteed (60% to 80% likelihood) (42,43). Return to the previous level of sport, if achieved, is likely to take 6 to 12 months (42,43,46).

Patellar Tendinopathy in a Nutshell

The clinical implications of recent patellar tendon research can be summarized as follows:

• Physicians should adopt the term "patellar tendinopathy" rather than the misnomer tendinitis when referring to patellar tendon overuse injury. The key pathology is tendinosis—collagen degeneration and its sequelae.
• A patient who presents with patellar tendinopathy for the first time may require 2 to 3 months to recover. A patient who has a long-standing injury may require 4 to 6 months to return to competition pain free and without recurrence.
• We recommend imaging only when the diagnosis is unclear. Imaging has not been shown to be a useful guide to the choice of management or prognosis. A focal hypoechoic region on ultrasound or a region of high signal on MRI is certainly no indication, per se, for surgery.
• Relative tendon unloading is critical for treatment success. This can be achieved by activity modification and by biomechanical correction. Biomechanical abnormalities may be anatomic (static and dynamic) or functional (from regional dysfunction).
• Progressive strengthening graduating to eccentric exercises are the treatment of choice. To prescribe exercise effectively requires thorough assessment of the patient's functional capacity and a skillful approach to gradually increasing the demand that the athlete imposes on the tendon.
• Return to full competitive sport after successful patellar tendon surgery takes 6 to 12 months, and only 60% to 75% of patients are able to return to former levels of sporting activity. Thus, the physician must be sure that an appropriate conservative treatment program has failed before suggesting surgery.

References

1. Khan KM, Bonar F, Desmond PM, et al: Patellar tendinosis (jumper's knee): findings at histopathologic examination, US and MR imaging: Victorian Institute of Sport Tendon Study Group. Radiology 1996;200(3):821-827
2. Khan KM, Cook JL, Taunton JE, et al: Overuse tendinosis, not tendinitis: a new paradigm for a difficult clinical problem. Phys Sportsmed 2000;28(5):38-48
3. Khan KM, Cook JL, Bonar F, et al: Histopathology of common tendonopathies: update and implications for clinical management. Sports Med 1999;27(6):393-408
4. Maffulli N, Khan KM, Puddu G: Overuse tendon conditions: time to change a confusing terminology. Arthroscopy 1998;14(8):840-843
5. Astrom M, Rausing A: Chronic Achilles tendinopathy: a survey of surgical and histopathologic findings. Clin Orthop 1995;316(Jul):151-164
6. Cook JL, Kiss ZS, Khan KM, et al: Reproducibility and clinical utility of tendon palpation to detect patellar tendinopathy in young basketball players. Br J Sports Med 2000, submitted
7. Blazina ME, Kerlan RK, Jobe FW, et al: Jumper's knee. Orthop Clin North Am 1973;4(3):665-678
8. Shalaby M, Almekinders LC: Patellar tendinitis: the significance of magnetic resonance imaging findings. Am J Sports Med 1999;27(3):345-349
9. Movin T, Kristoffersen-Wiberg M, Rolf C, et al: MR imaging in chronic Achilles tendon disorder. Acta Radiol 1998;39(2):126-132
10. Movin T, Kristoffersen-Wiberg M, Shalabi A, et al: Intratendinous alterations as imaged by ultrasound and contrast medium enhanced magnetic resonance in chronic achillodynia. Foot Ankle Int 1998;19(5):311-317
11. Yu JS, Popp JE, Kaeding CC, et al: Correlation of MR imaging and pathologic findings in athletes undergoing surgery for chronic patellar tendinitis. AJR Am J Roentgenol 1995;165(1):115-118
12. Cook JL, Khan KM, Harcourt PR, et al: A cross-sectional study of 100 athletes with jumper's knee managed conservatively and surgically: the Victorian Institute of Sport Tendon Study Group. Br J Sports Med 1997;31(4):332-336
13. Cook JL, Khan KM, Harcourt PR, et al: Patellar tendon ultrasonography in asymptomatic active athletes reveals hypoechoic regions: a study of 320 tendons: Victorian Institute of Sport Tendon Study Group. Clin J Sport Med 1998;8(2):73-77
14. Lian O, Holen KJ, Engebretson L, et al: Relationship between symptoms of jumper's knee and the ultrasound characteristics of the patellar tendon among high level male volleyball players. Scand J Med Sci Sports 1996;6(5):291-296
15. Khan KM, Cook JL, Kiss ZS, et al: Patellar tendon ultrasonography and jumper's knee in elite female basketball players: a longitudinal study. Clin J Sport Med 1997;7(3):199-206
16. Kiss ZS, Kellaway DP, Cook J, et al: Postoperative patellar tendon healing: an ultrasound study: VIS Tendon Study Group. Australas Radiol 1998;42(1):28-32
17. Khan KM, Visentini PJ, Kiss ZS, et al: Correlation of ultrasound and magnetic resonance imaging with clinical outcome after open patellar tenotomy: prospective and retrospective studies: Victorian Institute of Sport Tendon Study Group. Clin J Sport Med 1999;9(3):129-137
18. Khan KM, Tress BW, Hare WS, et al: Treat the patient, not the x-ray: advances in diagnostic imaging do not replace the need for clinical interpretation [Editorial]. Clin J Sport Med 1998;8(1):1-4
19. Almekinders LC, Temple JD: Etiology, diagnosis, and treatment of tendonitis: an analysis of the literature. Med Sci Sports Exerc 1998;30(8):1183-1190
20. Richards DP, Ajeman SV, Wiley JP, et al: Knee joint dynamics predict patellar tendinitis in elite volleyball players. Am J Sports Med 1996;24(5):676-683
21. Prilutskii BI, Zatsiorskii VM, Petrova LN: "Tendon" action of two-joint muscles during human locomotion: transfer of mechanical energy between links in shock-absorbing and push-off phases [in Russian]. Biofizika 1993;38(4):719-725
22. Prapavessis H, McNair PJ: Effect of instruction in jumping technique and experience jumping on ground reaction forces. J Orthop Sports Phys Ther 1999;29(6):352-356
23. Kaufman KR, Brodine SK, Shaffer RA, et al: The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med 1999;27(5):585-593
24. McCrory JL, Martin DF, Lowery RP, et al: Etiologic factors associated with Achilles tendinitis in runners. Med Sci Sports Exerc 1999;31(10):1374-1381
25. Cook JL, Kiss ZS, Khan KM, et al: Patellar tendon ultrasound in asymptomatic elite junior basketball players: a 12-month longitudinal study in 52 tendons. J Ultrasound Med 2000, in press
26. Rivenburgh DW: Physical modalities in the treatment of tendon injuries. Clin Sports Med 1992;11(3):645-659
27. Pellechia G, Hamel H, Behnke P: Treatment of infrapatellar tendinitis: a combination of modalities and transverse friction massage versus iontophoresis. J Sport Rehabil 1994;3:1315-1345
28. Davidson CJ, Ganion LR, Gehlsen G, et al: Rat tendon morphological and functional changes resulting from soft tissue mobilization. Med Sci Sports Exerc 1997;29(3):313-319
29. Gehlsen G, Ganion LR, Helfest R: Fibroblast response to variation in soft tissue mobilization pressure. Med Sci Sports Exerc 1999;31(4):531-535
30. Ramirez A, Schwane JA, McFarland C, et al: The effect of ultrasound on collagen synthesis and fibroblast proliferation in vitro. Med Sci Sports Exerc 1997;29(3):326-332
31. Enwemeka CS: The effects of therapeutic ultrasound on tendon healing: a biomechanical study. Am J Phys Med Rehabil 1989;68(6):283-287 [published erratum in Am J Phys Med Rehabil 1990;69(5):258]
32. Enwemeka CS: Laser biostimulation of healing wounds: specific effects and mechanisms of action. J Orthop Sports Phys Ther 1988;9:333-338
33. Almekinders LC, Deol G: The effects of aging, anti-inflammatory drugs, and ultrasound on the in vitro response of tendon tissue. Am J Sports Med 1999;27(4):417-421
34. Chan AK, Myrer JW, Measom GJ, et al: Temperature changes in human patellar tendon in response to therapeutic ultrasound. J Athletic Training 1998;33(2):130-135
35. Kraushaar BS, Nirschl RP: Tendinosis of the elbow (tennis elbow): clinical features and findings of histological, immunohistochemical, and electron microscopy studies. J Bone Joint Surg (Am) 1999;81(2):259-278
36. Shrier I, Matheson GO, Kohl HW III: Achilles tendonitis: are corticosteroid injections useful or harmful? Clin J Sport Med 1996;6(4):245-250
37. Almekinders LC: The efficacy of nonsteroidal anti-inflammatory drugs in the treatment of ligament injuries. Sports Med 1990;9(3):137-142
38. Fredberg U: Local corticosteroid injection in sport: a review of literature and guidelines for treatment. Scand J Med Sci Sport 1997;7(3):131-139
39. Clemmensen D, Pfeiffer-Jensen M, Fredberg U, et al: Ultrasonographic visualisation of inflamed tendons before and after local glucocorticosteroid, abstracted. Scand J Rheumatol 1998;41(suppl):27
40. Pfeiffer-Jensen M, Fredberg U, Clemmensen D, et al: Pain assessment in inflamed tendons before and after placebo and local glucocorticosteroid, abstracted. Scand J Rheumatol 1998;41(suppl):146
41. Capasso G, Testa V, Maffulli N, et al: Aprotinin, corticosteroids, and normosaline in the management of patellar tendinopathy in athletes: a prospective randomized study. Sports Exerc Inj 1997;3(2):111-115
42. Coleman BD, Khan KM, Maffulli N, et al: Studies of surgical outcome after patellar tendinopathy: clinical significance of methodological deficiencies and guidelines for future studies. Victorian Institute of Sport Tendon Study Group. Scand J Med Sci Sports 2000;10(1):2-11
43. Coleman BD, Khan KM, Kiss ZS, et al: Outcomes of open and arthroscopic patellar tenotomy for chronic patellar tendinopathy: a retrospective study. Am J Sports Med 2000;28(2):183-190
44. Testa V, Capasso G, Maffulli N, et al: Ultrasound guided percutaneous longitudinal tenotomy for the management of patellar tendinopathy. Med Sci Sports Exerc 1999;31(11):1509-1515
45. Zini R, Coari GC: Arthroscopic management of patellar tendinitis. J Sports Traumatol Related Res 1997;19(2):75-82
46. Maffulli N, Binfield PM, Leach WJ, et al: Surgical management of tendinopathy of the main body of the patellar tendon in athletes. Clin J Sport Med 1999;9(2):58-62

Tendinitis, Tendinosis, Tendinopathy: Why the Fuss?

The term "tendinitis" is entrenched in the clinical medicine lexicon to refer to painful overuse tendon conditions. Unfortunately, the suffix "itis" implies an inflammatory pathology whereas the chronic, painful tendon conditions are devoid of inflammatory cells (1). Thus, if nomenclature is to be evidence based, the term "tendinitis" seems rather inappropriate.

The most common pathology in chronic painful tendons is "tendinosis," which refers to collagen degeneration, increased ground substance, and neovascularization in the absence of inflammatory cells (2). Thus, "tendinosis" has replaced "tendinitis" in the official index of diagnostic codes in Sweden.

However, clinicians generally do not have the luxury of histopathologic diagnosis. Also, the Achilles paratenon may contain inflammatory cells. Furthermore, how could one be certain that inflammation was absent in a patient who presented with a short duration of symptoms, or when tendon pain was associated with inflammatory arthritis (eg, rheumatoid arthritis)?

Because the term "tendinopathy" refers to painful overuse tendon conditions without implying pathology, it is ideal for clinical diagnosis (3-5). This reserves the terms "tendinosis," "paratenonitis," and "tendinitis" as histopathologic labels. Although changing familiar nomenclature requires some effort, we feel that the term "tendinitis" must be avoided, as it has associations that are unfounded (3,4).

REFERENCES

1. Khan KM, Cook JL, Bonar F, et al: Histopathology of common overuse tendon conditions: update and implications for clinical management. Sports Med 1999;27(6):393-408
2. Puddu G, Ippoliro E, Postacchini F: A classification of Achilles tendon disease. Am J Sports Med 1976;4(2):145-150
3. Maffulli N, Khan KM, Puddu G: Overuse tendon conditions: time to change a confusing terminology. Arthroscopy 1998;14(8):840-843
4. Astrom M, Rausing A: Chronic Achilles tendinopathy: a survey of surgical and histopathologic findings. Clin Orthop 1995;316(Jul):151-164
5. Jozsa L, Balint BJ, Reffy A, et al: Fine structural alterations of collagen fibers in degenerative tendinopathy. Arch Orthop Trauma Surg 1984;103:47-51

Strengthening: Putting Theory Into Practice

Strengthening exercises have long been recognized as the keystone to successful management of tendinopathies (1-4). Well-designed studies have demonstrated the efficacy of strengthening as a treatment for both Achilles and adductor tendinopathy (5-7), but studies of strengthening for the patellar tendon have only been published in a book (2) and an abstract (8). Table A presents a strength program embracing the activities and timelines that our clinical experience has shown to be effective.

TABLE A. A Strengthening Program for Treatment of Patellar Tendinopathy*
Timing	Type of Overload	Activity
0-3 mo	Load endurance	Hypertrophy and strengthen calf, quadriceps, and gluteals
3-6 mo	Speed endurance	Weight-bearing, speed-specific loads
6+ mo	Combinations dependent on sport (eg, load+, speed)	Sports-specific rehabilitation
*Progression to the next level of the program should only be done if the previous workload is easily managed, pain is controlled, and function is satisfactory.

Initiating a program. Therapists often have concerns as to when and how they should begin a strengthening program. Even athletes with severe patellar tendinopathy should be able to begin some exercise, at the very least standing calf strength and isometric quadriceps work (figure A). On the other hand, the athlete who has not lost appreciable knee strength and bulk can progress quickly to the speed part of the program.

Both pain and the musculotendinous unit's ability to do work should guide the amount of strengthening activity. If pain is a limiting factor, then the program must be modified so that the majority of the work occurs relatively pain free and does not cause delayed symptoms—commonly pain the morning after exercise.

A subjective clinical rating system such as the Victorian Institute of Sport Assessment (VISA) score (9) (a numerical scale for assessing the severity of jumper's knee) (9,10) helps both the therapist and the patient measure progress, and it allows early detection of any worsening of symptoms.

Monitoring progress. If pain is under control, then it is essential to monitor the ability of the limb to complete the exercises with control and quality. Progression to the next level of the program should only be done if the previous workload is easily managed, pain is controlled, and function is satisfactory.

Because athletes with patellar tendinopathy tend to "unload" the affected limb to avoid pain, they commonly have not only weakness, but also abnormal motor patterns that must be reversed. Strength work must progress to single-leg exercises, as bilateral exercises only offer options to continue to unload the tendon. Some physicians and therapists maintain that quadriceps-only exercises such as leg extensions have a place in the rehabilitation of patients who have patellar tendinopathy, specifically to load the quadriceps exclusively, not allowing the calf and gluteals to "take over" the exercise.

Similarly, we have found that squats performed on a 30° decline board are effective in reducing the influence of the calf group in retarding knee flexion such as occurs in a normal squat done with the heels fixed (see figure 1 in main article). The therapist can help the patient progress by adding load and speed to the exercises, and then endurance can be introduced once the patient can do these exercises well. After that, combinations such as load (weight) and speed, or height (eg, jumping exercises) and load can be added. These end-stage exercises, including previously published eccentric programs (2,6), can provoke tendon pain and are only recommended after a sufficiently long rehabilitation period and when the sport demands intense loading. In several sports it may not be necessary to add height to the rehabilitation program at all, whereas in some sports (eg, volleyball), it is vital.

Finally, the overall exercise program must correct aberrant motor patterns such as stiff landing (noted previously) and pelvic instability. For example, weight-bearing exercises must be done within a functionally required range, and the pelvis position must be monitored and controlled at all times.

Reasons for failure. Failure in rehabilitation strength programs can stem from many sources. They include: too rapid a progression of rehabilitation; inappropriate loads (not enough strength or speed work, eccentric work too early or aggressively, insufficient single-leg work); too many electrotherapeutic modalities; and lack of monitoring patients' symptoms during and after therapy.

Rehabilitation and strength training must also continue through the return to sports, rather than ending immediately on return. Finally, plyometrics training can be performed inappropriately, not tolerated, or done unnecessarily.

References

1. Clement DB, Taunton JE, Smart GW: Achilles tendinitis and peritendinitis: etiology and treatment. Am J Sports Med 1984;12(3):179-184
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Ms Cook is a doctoral candidate at Griffiths University in Gold Coast, Queensland, Australia, and a physical therapist in the Victorian Institute of Sport Tendon Study Group in Melbourne. Dr Khan is a sports medicine physician at the Allan McGavin Sports Medicine Centre at the University of British Columbia, Vancouver. Dr Maffulli is a senior lecturer in the department of orthopedics at the University of Aberdeen, Scotland, and Mr Purdam is the director of physiotherapy in the Australian Institute of Sport, Canberra. This is the second of two articles on tendinopathies by Dr Khan and colleagues. The first, "Overuse Tendinosis, Not Tendinitis, Part 1: A New Paradigm for a Difficult Clinical Problem," appeared in May. Address correspondence to Karim M. Khan, MD, PhD, School of Human Kinetics, 210 War Memorial Gym, 6081 University Blvd, Vancouver, British Columbia V6T 1Z1; e-mail to kkhan@interchange.ubc.ca.