The rectus femoris is a muscle located in the anterior compartment of the quadriceps and it has a double function. On the one hand, it aids in the flexion of the thigh at the hip joint, and, on the other hand, it helps extend the leg at the knee joint.

One injury this muscle can suffer is the central tendon tear. It’s not a very common one but it’s normally related to sports. Most rectus femoris central tendon injuries can be treated by nonoperative means, but some tend to reinjure, resulting in chronic symptoms.  In these cases, the surgical treatment could be beneficial to the athlete if the rectus femoris central tendon rupture becomes chronic. 

Muscle tissue vs. tendinous tissue

Normally, muscle tissue injuries tend to heal well and without complications (read reference 1 below). If the injury also affects the tendon tissue, the healing process might be more demanding and require more time (read reference 2). The tendon tissue has poorer biology to regenerate from injury; therefore, this needs to be taken into account when the return to play of an athlete is being decided.  Injuries involving the central tendon structure tend to be more severe and take longer to heal than typical muscle strains involving only muscle tissue (read references 3,2,4).

In fact, if a reinjury occurs during the healing process of the central tendon, then the outcome in conservative treatment can have a poor prognosis (read references 2,4). 

While more information has been recently published about the surgical treatment of biceps femoris central tendon injury, there is scarce information in the literature regarding rectus femoris central tendon injuries (read references 3,2,4,5). 

This is why, in order to help in the description of the clinical picture, the findings of the magnetic resonance imaging (MRI), and surgical treatments results of the rectus femoris central tendon injuries, the Sports Trauma Investigation Unit of Mehiläinen Hospital NEO (Turku, Finland) carried out the study called Chronic and Recurrent Rectus Femoris Central Tendon Ruptures in Athletes (Lasse Lempainen et al, 2021).

Between the years 2016 and 2019, a total of 12 professional athletes were surgically treated for a rectus femoris central tendon rupture in that hospital. The median age of surgically treated patients was 24.5 years (range, 18-29 years), and the time to undergo surgery after the primary injury was 7 months (range, 4-12 months). Most were referred to this centre from other hospitals and football teams from abroad after the failure of nonoperative treatments. In the study, presurgical MRI scans were obtained and compared with the surgical findings. The time of return to play was recorded, and the outcome of surgical treatment was evaluated with previously validated criteria. 

Rectus femoris central tendon surgery and post surgical rehabilitation

The indications for surgery were injured rectus femoris central tendons seen on MRI scans with the following prolonged chronic symptoms:
 

• Career disability >4 months
• Blunt/sharp pain
• Discomfort
• Ache 
• Tightness while performing sports

The athletes who underwent surgery were closely monitored by their doctors during the whole rehab process. The surgically treated athletes were monitored for at least 12 months. During the first 3 to 4 months, there were monthly routine visits.  After that, visits were scheduled only as they were necessary. Additional long-term follow-ups were scheduled for study purposes. 

To evaluate the recovery, the patients were asked about possible symptoms (pain, weakness, and stiffness), overall satisfaction, and their return to preinjury level of sport performance.

During the rehabilitation process, an active stretching of the anterior operated thigh was avoided during a period of 2 to 3 weeks. This would allow the treated area to heal properly. No hip or knee braces were used, and the patient was allowed immediate mobilization with weightbearing as tolerated with crutches.

Study outcomes and conclusions

Rectus femoris central tendon rupture is a poorly known and understood injury.  The main finding of this study was that, after well-carried surgery with structured rehabilitation, all injured athletes with chronic and/or recurrent rectus femoris injuries were able to return to play at their preinjury levels of performance. 

Overall, 10 out of 12 patients who underwent surgery had a good outcome (83%), and 2 had a moderate outcome (17%).  All were able to return to sport at their preinjury levels 2.5 to 4 months postoperatively.  In some cases, the long period between the primary injury and surgery did not prevent the athlete’s return to sports afterward. Furthermore, all athletes felt that they had clearly benefited from the surgery and that their athletic performance had improved after the operation.  All athletes said that they would undergo surgery again.

Study Limitations

Results after surgery were evaluated by the ability of the athlete to return to sports and by analysing the subjective symptoms of each athlete. The central tendon rupture of the rectus femoris is a rare injury; therefore, comparison groups are not gathered at present, and, as a result, the outcomes could not be compared with those of a non-surgically treated group of injured people.

The rehabilitation program did not include systematic strength measurements, which should be taken into consideration for future prospective studies to better understand the course of return to play after surgery.  

In any case, more research should be performed to clarify the central tendon injury treatment methods. It is still not clear which central tendon injuries benefit from more aggressive therapy, including surgery.2,4 Based on the present study, surgical treatment should at least be considered if the athlete is not able to return to play and symptoms have continued for 4 to 5 months after rectus femoris central tendon injury.  

References:

1. Maffulli N, Oliva F, Frizziero A, et al. ISMuLT guidelines for muscle injuries. Muscles Ligaments Tendons J. 2014;3(4):241-249. 

2. Brukner P, Connell D. “Serious thigh muscle strains”: beware the intramuscular tendon which plays an important role in difficult ham- string and quadriceps muscle strains. Br J Sports Med. 2016; 50(4): 205- 208. 

3. Balius R, Maestro A, Pedret C, et al. Central aponeurosis tears of the rectus femoris: practical sonographic prognosis. Br J Sports Med. 2009; 43(11):818- 824. 


4. Comin J, Malliaras P, Baquie P, Barbour T, Connell D. Return to com- petitive play after hamstring injuries involving disruption of the central tendon. Am J Sports Med. 2013; 41(1):111- 115. 

5. Lempainen L, Kosola J, Pruna R, et al. Central tendon injuries of hamstring muscles: case series of operative treatment. Orthop J Sports Med. 2018;6( 2): 2325967118755992.