Introduction

Eccentric exercises for patellar tendinopathy (PT) have received strong recommendations but may be pain-provoking. The authors, therefore, evaluated the effectiveness of progressive tendon-loading in patellar tendinopathy (PTLE), which has been proposed in the management of PT earlier on, compared to eccentric exercise therapy (EET) as recommended by several guidelines.

Methods

A prospectively registered RCT was designed to compare PTLE and EET in recreational, competitive, and professional athletes with PT aged 18-35. PT had to be associated with training and competition. Diagnosis of PT was based on pain provocation on palpation or during single-leg squat, and confirmed by abnormalities on ultrasound and Doppler. Patients were allocated to receive either PTLE or EET.

PTLE group program: 

Patients were instructed to perform progressive loading exercises based on pain response in four different stages of rehabilitation.

• Stage 1: Daily isometric single-leg leg press or leg extension was performed for 5 repetitions of 45 seconds at 60° of knee flexion (or at 90° knee flexion for the wall sit) at 70% of maximal voluntary contraction. If no such machine was available an isometric unipodal wall sit was performed.
• Stage 2: Isometric exercises of stage 1 were continued on every 1st day and isotonic exercises were commenced every 2nd day. The isotonic exercises also consisted of the leg-press or leg extension. 4 sets of 15 repetitions between 10° and 60° of knee flexion were performed and this was slowly progressed to 4 sets of 6 repetitions with increasing load and knee angles from almost full extension to 90° of flexion. Walking lunges and step-ups were performed in case no leg-press device was available.
• Stage 3: Plyometric loading and running exercises were performed every 3rd day, with stage 1 and 2 exercises performed every 1st and 2nd day, respectively. In this stage jump squats, box jumps, and cutting maneuvers were performed in 3 sets of 10 repetitions using both legs and gradually progressed to 6 sets of 10 repetitions on 1 leg.
• Stage 4: sport-specific exercises every 2-3 days and stage 1 isometric exercises on other days.
• Return to competition with the advice to perform the exercises of stages 1 and 2 twice per week as maintenance.

Progressions through the stages were based on pain provocation during the single-leg squat. If pain during this test was in the acceptable range (VAS ≤ 3/10) and the exercises of the stage had been performed for at least one week, the next stage could be commenced.

EET group program:

• Stage 1: Patients were instructed to perform pain-provoking exercises twice daily for 12 weeks. A single-leg decline squat (25° slope) with a downward eccentric component on the symptomatic leg and an upward concentric component on the contralateral leg was performed. The exercise had to provoke at least 5/10 on the VAS and this was achieved using additional load where necessary.
• Stage 2: In this stage, sport-specific exercises were performed and supplemented by stage 1 maintenance exercises twice per week.

Progression to stage 2 was allowed if there was complete adherence to stage 1 and when pain during eccentric exercises with additional weights was acceptable (VAS ≤ 3/10). Return to sport (RTS) was allowed after 4 weeks and when pain during a single-leg squat was acceptable (VAS ≤ 3/10).

PTLE and EET:

Both groups received additional exercises targeting PT risk factors. The additional exercises were flexibility exercises of the hamstrings, quadriceps, gastrocnemius, and soleus, strength exercises for hip abductors and extensors using resistance bands, calf strengthening exercises, and core stability. Advice and education were given to both groups explaining PT, the expected management, the positive influence of exercise, and the importance of gradual RTS. The relationship between load and pain was also explained. Patients in both groups were advised to modify their athletic activities when pain-provoking. A substantial reduction of the activity or a complete stop for at least 4 weeks was recommended. Performing activities within the limits of acceptable pain was advised.

Results

VISA-P:

At 24 weeks, but not at 12 weeks, a significant difference was found favoring PTLE. Sensitivity analyses revealed consistent results, except when missing results were replaced by the worst outcome of the treatment group. Both groups had equal numbers of patients achieving the minimal clinically important difference (MCID).>

RTS, patient satisfaction, adherence, and pain:

No significant difference in RTS rate between PTLE and EET was found. Patients in both the PTLE and EET groups reached similar levels of patient satisfaction at 12 and 24 weeks. However, the PTLE group had a significantly higher percentage of patients with satisfaction reaching “excellent” (38% vs 10%). RTS and satisfaction were not influenced by symptom duration. No between-group difference was found for patient satisfaction at 12 or 24 weeks. At 24 weeks, pain in the PTLE group was significantly lower (2/10 vs 4/10 in the EET group).

Talk nerdy to me

Several strengths can be noted. This investigator-blinded RCT was a priori registered which is good since this way protocol deviations are unlikely. A thorough screening for PT was performed prior to the inclusion of subjects into the study. The allocation was concealed for the main investigator and sports physician, so they were unbiased in their assessment. The authors made a distinction between acute and chronic PT by stratifying the randomization based on early or longstanding PT. Adjustments for baseline variables were predefined. Good results for both programs were found notwithstanding the fact that they were unsupervised.

As with all research, this study shows some limitations. First of all, pain was significantly lower after PTLE, but this difference is not clinically relevant, since a reduction of at least 3 points on the VAS scale is proposed to be an important change. The ultrasound evaluation of the patellar tendon was performed, however, it was unclear whether findings were compared bilaterally. Overall low adherence rates were observed in both groups, suggesting an unsupervised program may not be suitable for every subject. It would have been interesting to see a subanalysis comparing the most adherent subjects in both groups.

Some precautions should be taken into consideration. The return to sports was low: at 24 weeks less than half of subjects returned to sports at their preinjury level and an equal percentage of patients in both groups reached the MCID, suggesting there is still room for improvement (for example with a supervised program). The authors indicated that when adjusting for missing values in the best case and most likely scenario the PTLE was superior regarding the primary outcome. However, this was not true when the worst-case scenario (which replaced the missing value in the PTLE group with the worst value observed in this group) was analyzed. Therefore the result favoring the PTLE group for the VISA-P score may not be fully trustworthy. A large spread for the outcome was observed so not every subject had the same benefit from the exercise programs, indicating the importance of an individualized treatment approach.

Take home messages

PTLE may be a good option if EET is too pain-provoking for young recreational, competitive, and professional athletes with PT. This PTLE may achieve greater improvements in pain, function, and ability to play sports (as measured by the VISA-P) than the EET. The PTLE group reached equal improvements in RTS rate, patient satisfaction, and pain compared to the EET program. After PTLE more patients report an “excellent satisfaction” score. There may be room for improvement when the PTLE program is performed in a supervised environment.

Reference

Breda, S. J., Oei, E. H., Zwerver, J., Visser, E., Waarsing, E., Krestin, G. P., & de Vos, R. J. (2021). Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomised clinical trial. British journal of sports medicine, 55(9), 501-509.