Surgery for patella tendinopathy (jumper's knee)

Background

Patella tendinopathy is a painful condition that commonly affects jumping athletes who train a lot, for example those who play volleyball and basketball. Many people with the condition are unable to continue their chosen sport at the same level of competition or intensity of training. There are many treatments for the condition, the most common of which is a particular type of exercise called eccentric exercise (where the tendon is under tension while the muscle lengthens).

Other treatments for patella tendinopathy include oral and topical analgesia (pain-relief medication taken orally or applied to the skin), various injectables (e.g. corticosteroids) and surgery. Surgery is used if other treatments fail, and is the treatment assessed in this review.

Study characteristics

This Cochrane Review is current to July 2018. We searched online databases for all studies (specifically randomised controlled trials) that compared surgical treatment with non-operative treatment in adults with patellar tendinopathy. We found two studies; they compared open surgical removal to eccentric exercises (one study involving 40 people) and arthroscopic surgery to sclerosing injections (these scar and block the blood vessels supplying nerve fibres to the diseased tendon) (one study involving 56 people). The studies were performed in an outpatient setting in two countries (Norway and Sweden). The majority of people in the studies were male, with a mean age ranging from 27 to 31 years, and mean symptom duration of 24 to 33 months. Trials were conducted without funding (financial support) from industry (medical or device companies), but some authors from the one study received funding from pharmaceutical companies in addition to research funding from non-industry sources.

Key results

Compared with eccentric exercises, open surgery offered little benefit at 12 months (results for individual outcomes as follows).

Pain (lower scores mean less pain)

Improved by 4% (ranging from 4% worse to 12% better) or by 0.4 points on a scale of zero to 10 points.

People who had surgery rated their pain as 1.3 points.

People who had eccentric exercises rated their pain as 1.7 points.

Global assessment of success (those who reported no pain at 12 months)

10% fewer people had no pain (ranging from 38% less to 18% more), or 10 fewer people out of 100.

Twenty-five out of 100 people had no pain with surgery.

Thirty-five out of 100 people had no pain with eccentric exercises.

Withdrawals

No participants in either group withdrew from the study.

The study did not report on quality-of-life improvements or adverse events (including tendon ruptures).

Compared with sclerosing injections, arthroscopic (keyhole) surgery offered some reduction in pain and improvement in participant global assessment of success at 12 months (results for individual outcomes as follows; further studies are likely to change these results).

Pain (lower scores mean less pain)

Improved by 28% (ranging from 15% to 42% better) or by 28 points on a scale of zero to 100 points.

People who had surgery rated their pain as 12.8 points.

People who had sclerosing injection rated their pain as 41.1 points.

Global assessment of success (participant-reported success, higher score is better)

Improved by 34% (ranging from 19% to 49% better) or by 33.9 points on a scale of zero to 100 points.

People who had surgery rated their pain as 86.8 points.

People who had sclerosing injection rated their pain as 52.9 points.

Withdrawals

One person from each group (4%) withdrew from the study for reasons unrelated to the treatment.

The study did not report on quality-of-life improvements, functional score improvements or adverse events (including tendon ruptures).

Quality of the evidence

We decided the evidence was low-certainty due to flaws in the design of the studies that may over-estimate benefits of treatment. For example, people involved in the study were aware of which treatment they were receiving, the studies selectively reported some results but not others, and there was imprecision in the results due to the small number of participants and trials. Therefore, we are uncertain if surgery has any benefits over eccentric exercises or sclerosing injections for treating patellar tendinopathy in adults. Further studies are likely to change the results.

Authors' conclusions: 

We are uncertain if surgery is beneficial over other therapeutic interventions, namely eccentric exercises or injectables. Low-certainty evidence shows that surgery for patellar tendinopathy may not provide clinically important benefits over eccentric exercise in terms of pain, function or participant-reported treatment success, but may provide clinically meaningful pain reduction and treatment success when compared with sclerosing injections. However, further research is likely to change these results. The evidence was downgraded two levels due to the small sample sizes and susceptibility to bias. We are uncertain if there are additional risks associated with surgery as study authors failed to report adverse events. Surgery seems to be embedded in clinical practice for late-stage patella tendinopathy, due to exhaustion of other therapeutic methods rather than evidence of benefit.

Read the full abstract...
Background: 

Patellar tendinopathy is an overuse condition that commonly affects athletes. Surgery is usually offered if medical and physical therapies fail to treat it effectively. There is variation in the type of surgery performed for the condition.

Objectives: 

To assess the benefits and harms of surgery for patellar tendinopathy in adults.

Search strategy: 

We searched the following databases, to 17 July 2018: the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Library, OVID MEDLINE, OVID Embase, clinical trial registries (www.ClinicalTrials.gov) and the WHO trials portal (www.who.int/ictrp/en/).

Selection criteria: 

We included all randomised controlled trials (RCTs) that compared surgical techniques (open or arthroscopic) with non-operative treatment (including placebo surgery, exercise or other non-surgical modalities) in adults with patellar tendinopathy.

Major outcomes assessed were knee pain, function, quality of life, participant global assessment of success, withdrawal rate, proportion with adverse events and proportion with tendon rupture.

Data collection and analysis: 

Two review authors selected studies for inclusion, extracted trial characteristics and outcome data, assessed the risk of bias and assessed the quality of the evidence using GRADE.

Main results: 

Two trials (92 participants) met our inclusion criteria. Participants in both trials were followed for 12 months. Neither trial compared surgery to placebo surgery. One trial (40 randomised participants) compared open surgical excision with eccentric exercises, and the other compared arthroscopic surgery with sclerosing injections (52 randomised participants). Due to the nature of the interventions, neither the participants or the investigators were blinded to the group allocation, resulting in the potential for performance and detection bias. Some outcomes were selectively not recorded, leading to reporting bias. Overall, the certainty of the evidence from these studies was low for all outcomes due to the potential for bias, and imprecision due to small sample sizes.

Compared with eccentric exercises, low-certainty evidence indicates that open surgical excision provides no clinically important benefits with respect to knee pain, function or global assessment of success. At 12 months, mean knee pain — measured by pain with standing jump on a 10-point scale (lower scores indicating less pain) — was 1.7 points (standard deviation (SD) 1.6) in the eccentric training group and 1.3 (SD 0.8) in the surgical group (one trial, 40 participants). This equates to an absolute pain reduction of 4% (ranging from 4% worse to 12% better, the minimal clinically important difference being 15%) and a relative reduction in pain of 10% better (ranging from 30% better to 10% worse) in the treatment group. At 12 months, function on the zero- to 100-point Victorian Institute of Sport Assessment (VISA) scale was 65.7 (SD 23.8) in the eccentric training group and 72.9 (SD 11.7) in the surgical group (one trial, 40 participants). This equates to an absolute change of 7% better function (ranging from 4% worse to 19% better) and relative change of 25% better (ranging from 15% worse to 65% better, the minimal clinically important difference being 13%). Participant global assessment of success was measured by the number of people with no pain at 12 months: 7/20 participants in the eccentric training group reported no pain, compared with 5/20 in the open surgical group (risk ratio (RR) 0.71 (95% CI 0.27 to 1.88); one trial, 40 participants). There were no withdrawals, but five out of 20 people from the eccentric exercise group crossed over to open surgical excision. Quality of life, adverse events and tendon ruptures were not measured.

Compared with sclerosing injection, low-certainty evidence indicates that arthroscopic surgery may provide a reduction in pain and improvement in participant global assessment of success, however further studies are likely to change these results. At 12 months, mean pain with activities, measured on a 100-point scale (lower scores indicating less pain), was 41.1 (SD 28.5) in the sclerosing injection group and 12.8 (SD 19.3) in the arthroscopic surgery group (one trial, 52 participants). This equates to an absolute pain reduction of 28% better (ranging from 15% to 42% better, the minimal clinically important difference being 15%), and a relative change of 41% better (ranging from 21% to 61% better). At 12 months, the mean participant global assessment of success, measured by satisfaction on a 100-point scale (scale zero to 100, higher scores indicating greater satisfaction), was 52.9 (SD 32.6) in the sclerosing injection group and 86.8 (SD 20.8) in the arthroscopic surgery group (one trial, 52 participants). This equates to an absolute improvement of 34% (ranging from 19% to 49%). In both groups, one participant (4%) withdrew from the study. Functional outcome scores, including the VISA score, were not reported. Quality-of-life assessment, adverse events, and specifically the proportion with a tendon rupture, were not reported.

We did not perform subgroup analysis to assess differences in outcome between arthroscopic or open surgical excision, as we did not identify more than one study with a common comparator.

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