Introduction

Prevention of (knee) OA is recommended since it is the most common joint disorder in people worldwide. Knee OA is a multifactorial condition but is often resulting from acute injuries to the knee such as meniscus and cruciate ligament injuries. Other than ACL tears, there is evidence with a low to moderate degree of certainty that a variety of single and multistructure knee injuries raise the risk of developing OA symptoms. Among these injuries are also injuries to the meniscus. In this light, acting right in case a younger individual sustains a meniscus tear is of utmost importance. Therefore, the therapeutic options should also prevent further changes. Currently, the two mainstays of treatment (exercise and arthroscopic surgery) are also thought to be related to the risk of developing and progressing OA. This study wanted to determine whether the initial treatment strategy chosen was related to the development of structural knee joint changes. Which type of meniscus treatment to avoid OA progression should be opted for?

Methods

This study was a secondary analysis of the DREAM trial, where exercise was compared to arthroscopic meniscal surgery in young adults who sustained a meniscal tear. Participants were eligible when they had an MRI-confirmed meniscal tear and were between 18-40 years of age. Congenital discoid meniscus or displaced bucket handle tears resulting in acute locking of the knee or an extension deficit were excluded.

To study the optimal meniscus treatment to avoid OA progression, they were randomly assigned to receive exercise or arthroscopy. The exercise consisted of a 12-week program with 2 supervised sessions per week. These participants were educated in the beginning and at the end of the program. We described the components of the exercise program in one of our previous research reviews. But in brief, the program consisted of:

• Warm up
• Reducing swelling and increasing range of motion
• Neuromuscular exercises: sensorimotor control and functional joint stability
  • Knee bends, pelvic lifts, planks, side planks, stair climbing, outer thigh, and inner thigh exercises using an exercise band, slide-exercise sideways lunges
• Strengthening exercises: increasing muscle strength and mass​​
  • One-legged leg press, one-legged knee extension, one-legged knee flexion, and kettlebell swings

The neuromuscular exercises were tailored to each patient’s needs, with two to six levels of difficulty and two to three sets of 10-15 repetitions. Neuromuscular exercises were started at a level determined by the physical therapist based on visual inspection of the quality of the movement and sensorimotor control; while minimal exertion, pain during the exercise, and a feeling of control over the movement were determined by the patient.

For the strengthening exercises, two sets of 15 repetitions were used to begin with, then three sets of 12 repetitions, three sets of 10 repetitions, and lastly three sets of 8 repetitions. The strengthening exercises were progressed according to the +2 principle, meaning that fewer repetitions were performed per set and more weight was introduced when the patient could complete two extra repetitions in the last set.

The arthroscopy encompassed either a partial meniscectomy or meniscus repair.

The primary outcome of interest was the difference in worsening structural knee damage between the group receiving arthroscopy or exercise. This was verified by comparing MRI at baseline and 2 years. The structural damage was defined using a modified version of the Anterior Cruciate Ligament OsteoArtrhritis Score (ACLOAS), which is a semiquantitative MRI-based outcome measure.

• Cartilage damage is scored from 0 to 6 in 14 subregions
• Osteochondral damage is scored from 0 to 4 in 14 subregions
• Osteophytes are scored from 0 to 7 in 12 locations.

The scores for cartilage damage, osteochondral damage, and osteophytes were summed. Worsening of individual MRI features includes new or progressed damage in one subregion and progression in the number of subregions affected. Next to these outcomes, bone marrow lesions, knee joint effusion/synovitis, and ligament status were also considered. The KOOS questionnaire at baseline and 2 years was included as a patient-reported outcome. This was the primary outcome of the primary DREAM trial.

Results

A total of 121 patients with meniscal tears were included and randomized to receive arthroscopy or exercise. Of them, 82 consented to participate in the follow-up study at 2 years. They were on average 29.5 years old and most of them were active. The duration of their symptoms was between 0-12 months, and mostly the injury had a (semi)traumatic onset. At baseline, the groups were similar, except for age and a slightly better KOOS score in the surgery group.

At 1 year, 16 of 61 patients (26%) crossed from the exercise group to arthroscopy. Between 1 and 2 years, 2 more patients crossed over to arthroscopy, while 4 patients from the arthroscopy group had a second knee surgery.

Considering the outcomes, at baseline, there were no differences in the type of tears between the groups. Only a few structural changes were observed on MRI. Throughout the 2-year study period, 9% of participants showed worsening cartilage damage and 3% of participants had osteophytes. This worsening was equal among the exercise group and the arthroscopy group. In most participants, bone marrow lesions, knee effusion/synovitis, Hoffa synovitis, and Baker’s cysts were unchanged, with no between-group differences.

Equally, there were no significant differences between the groups for the KOOS outcomes from baseline up to 2 years. The authors indicate that the crude and adjusted between-group difference was in favor of the exercise group, however, this was not significant. Most of the improvement was attained in the first 6 months. At 2 years, the arthroscopy group improved by 16.4 points (95% CI 10.4-22.0) and the exercise group by 21.5 points (95% CI 15.0-28.0) and this was reflected in the different KOOS subscales. The improvements in the WOMET scale supported the KOOS outcomes.

Questions and thoughts

This study found less severe worsening of the knee than in comparable studies. This could have been due to the relatively young population whereas other studies mostly include people with more degenerative meniscus lesions instead of the more acute traumatic onset injuries in this study. Furthermore, the inclusion criteria only allowed people without ligament ruptures. In the study by Pedersen et al. (2020), complete ACL tears and concomitant meniscus injuries lead to worse knee function in sport and recreation 2 to 10y post ACL reconstruction. Here the meniscus was the only injured tissue, which may have a better prognosis than combined injuries. The results of this study were in line with the study by van der Graaff et al. (2022) and Damsted et al. (2023), which we already reviewed in the past.

Talk nerdy to me

This was a secondary analysis of the DREAM trial that compared exercise to arthroscopy for meniscus injuries in young adults. The original study found that early meniscal surgery was not more beneficial to exercise and education with optional delayed surgery among young, active adults with meniscal injuries.

The inter-rater agreement and reliability of the MRI assessments were reported to be substantial to almost perfect.

The MRI outcomes were consistent with the primary outcomes of the original study.

An important part of participants were lost to follow-up (32%), although, there were no baseline differences between the participants followed and those lost to follow-up.

Since exercise leads to the same outcomes compared to surgery, exercise would be the preferred meniscus treatment to avoid OA progression since the related complications are potentially less severe as compared to surgery.

Take-home messages

This study supports the findings of the DREAM trial and other related studies (STARR) that found that exercise and education should be the mainstay of treatment for meniscal injuries. The comparison led to benefits from the exercise program on patient-reported outcomes and importantly, it did not lead to worsening structural knee outcomes such as cartilage damage and osteophytes development. Even in young adults who have a (semi)traumatic onset, the 2-year worsening of MRI-defined structural damage was limited and similar between those treated with surgery or exercise with optional delayed surgery. Both groups had similar clinically relevant improvements in KOOS, suggesting the choice of treatment strategy does not impact 2-year structural knee damage or patient outcomes. Exercise should be the first option for torn meniscus treatment to avoid OA progression in young adults.

Reference

Clausen SH, Skou ST, Boesen MP, Radev DI, Kurt EY, Damsted C, Hölmich P, Lind M, Tørring S, Isaksen C, Varnum C, Englund M, Thorlund JB. Two-year MRI-defined structural damage and patient-reported outcomes following surgery or exercise for meniscal tears in young adults. Br J Sports Med. 2023 Nov 30;57(24):1566-1572. doi: 10.1136/bjsports-2023-107352. PMID: 37879858.