March 22, 2016
5 min read

BLOG: More data needed to better predict return to play in athletes after patella stabilization

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As sports medicine physicians, a benchmark by which we are often measured is the ability to return an athlete to the highest level of sport following injury and/or surgery. Success is not defined solely by subjective scores or objective examination findings, but by the ability to bring an athlete safely back to optimal performance without re-injury.

As we have learned from the ACL literature, there is a disconnect between perception and reality. There is an expectation that ligament reconstruction delivers early and successful return to play (RTP) in most athletes. The harsh reality is a substantial number of athletes following ACL reconstruction fail to return to sport or fail to regain their pre-injury level of performance. How are we doing regarding RTP and return to prior performance (RPP) in our athletes following patella stabilization?

Seth L. Sherman

Ryan J. Pomajzl


Little evidence on efficacy of ACL reconstruction

Unfortunately, there is limited evidence to help us to answer this challenging question. Most studies in the existing literature are retrospective and have critical omissions. Many do not give specific timeframes or criteria for RTP following injury/surgery, and most do not record RTP rates or RPP. Two recent studies on the nonoperative management of patella instability may help provide valuable natural history data. Atkin and colleagues demonstrated that although 69% are able to RTP at 6 months, 58% of these patients reported impaired function with strenuous activity. Magnussen and colleagues reported that at a mean 3.3 years following index patella dislocation event, only 26% of patients were able to return to their desired sporting activity. Note that these were in patients who never had another dislocation event. These sobering numbers may provide a rationale for operative treatment in athletes to improve the predictability of RTP/RPP and to reduce time lost in this challenging population.

While there is a growing body of literature that demonstrates good to excellent subjective and objective results following patella stabilization surgery, there remains a paucity of information specifically on RTP and RPP. Fisher and colleagues performed a systematic review of 21 studies that asked specific questions about rehabilitation guidelines and RTP following medial patellofemoral ligament (MPFL) reconstruction. Conclusions were unfortunately limited in scope, noting that poor study methodology limited the validity of information. Of the studies that met inclusion criteria, only two reported RPP and only 13 studies reported a specific timetable for return to sport. Return to performance in those studies was 77.3%, and the timeframe for RTP varied from 3 months to 6 months.

Lippacher and colleagues reported on a large series of MPFL reconstructions and demonstrated 100% RTP, but only 33% RPP at a median of 3 months to 12 months. Ambrozic and Novak reported that 89% of RTP and 70% of RPP patients were released for unrestricted activity at 6 months postoperatively. Schneider and colleagues recently performed a systematic review of 14 studies and demonstrated an 84.1% RTP rate following MPFL reconstruction (1.2% risk of recurrent instability) in a young, active population (mean age 24.4 years, Tegner score 5.7). Return to prior performance and timeframe/criteria for RTP were not given.

There are even fewer data to guide our athletes with patella instability undergoing tibial tubercle osteotomy (TTO) or combined MPFL and TTO. In the largest series in the literature, Tjoumakaris and colleagues reported on 41 athletes following TTO for patella instability. They demonstrated excellent subjective outcomes (IKDC, KOOS and Lysholm scores) and a RTP rate of 97% at a mean 46 months. Burnham and colleagues performed a systematic review of combined MPFL reconstruction and TTO. Despite reporting excellent subjective outcomes, there was no available information on timeframe/criteria for return to sport or on RTP and RPP.

Key deficiencies on prediction of RTP

While the above information provides optimism regarding predictable RTP following patella stabilization surgery, it does not represent definitive evidence. We are missing major elements of the overall picture and rely on imperfect data in our daily counseling of athletes. Key deficiencies include:

Lack of prospective investigation and multivariate analysis of risk factors for failure to RTP and RPP. There is momentum to initiate a large scale prospective, multicenter study of patients following patella stabilization surgery. This effort will shed light on critical patient specific factors (i.e., demographics, injury pattern and concomitant injuries), technical factors (i.e., surgical technique, graft choices and concomitant cartilage restoration) and rehabilitation-related factors (i.e., criteria for RTP) that influence RTP and RPP.

Lack of validation and/or universal adoption of strict criteria for RTP following patella stabilization. The 2013 International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Sports Medicine Committee published safe return to sport criteria after patellofemoral instability to guide clinicians in determining when an athlete is ready for competition (Table). Furthermore, Ménetréy and colleagues used the literature pertaining to return to sport after ACL reconstruction to develop six clinical criteria. These criteria included the following: no pain; no effusion; no patellofemoral instability; full range of motion; nearly symmetrical strength (85% to 90%); and excellent dynamic stability. This effort is a great start and should be applauded. At present, there should be a push toward clinical validation of these recommendations following patella stabilization surgery and routine use of these in patellofemoral publications.

International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine criteria for RTP after patellofemoral instability

  • Full or near full range of motion

  • No knee effusion

  • No complaints of knee pain or knee instability

  • Satisfactory core strength and endurance

  • Completed neuromuscular training/proprioception

  • Acceptable control with dynamic activities

  • Limb Symmetry Index greater than 85% on hop tests

  • Adequate performance with a physical therapist during sport-specific drills simulating the intensity and movement patterns of the given sport

  • Athlete demonstrates a psychological readiness to return to sport (SANE score greater than 80 of 100)

  • Complete radiographic healing of bone if bony surgery is involved

Source: International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine

Lack of accurate documentation of a timeframe for RTP, RTP rates and RPP. The lack of standardized documentation makes it a challenge to provide answers to athletes on questions regarding a timeframe for RTP and rates of RPP. At present, our best information on MPFL reconstruction includes high RTP rates (84% to 100%), modest RPP rates (33% to 77%) and a variable timeframe for return (i.e., 3 months to 12 months). Universal reporting of RTP and RPP rates in patellofemoral publications will help set patient expectations. We will also better learn how concomitant procedures (i.e., TTO and cartilage restoration) influence RTP and RPP.

Overall, this is an exciting time to be a patellofemoral surgeon. We have an evolving skill set that allows for the precise diagnosis and treatment of patella instability. Let us build upon the work of our predecessors with the goal of safely returning our athletes to the highest levels of sporting competition without re-injury.



Ambrožič B, et al. The influence of medial patellofemoral ligament reconstruction on clinical results and sports activity level. Phys Sportsmed. 2016;Feb 24:1-8.

Atkin DM, et al. Am J Sports Med. 2000;28(4):472-479.

Burnham JM, et al. Arthroscopy. 2016;doi:10.1016/j.arthro.2015.11.039.

Fisher B, et al. Arthroscopy. 2010;doi:10.1016/j.arthro.2010.04.005.

Lippacher S, et al. Am J Sports Med. 2014;doi:10.1177/0363546514529640.

Magnussen RA, et al. Primary patellar dislocations without surgical stabilization or recurrence: How well are these patients really doing? Knee Surg Sports Traumatol Arthrosc. 2015 July 28; [Epub ahead of print] PMID: 26215775.

Ménétrey J, et al. Knee Surg Sports Traumatol Arthrosc. 2014;doi:10.1007/s00167-014-3172-5.

Schneider DK, et al. Am J Sports Med. 2016 Feb 12. pii:0363546515624673.

Tjoumakaris FP, et al.Am J Sports Med. 2010;doi:10.1177/0363546509357682.

For more information:

Seth L. Sherman, MD, is an assistant professor of orthopedic sports medicine in the Department of Orthopaedic Surgery at the University of Missouri in Columbia, Mo. Ryan J. Pomajzl, MD, is a sports medicine fellow in the Department of Orthopedic Surgery at the University of Missouri in Columbia, Mo.

Disclosures: Sherman and Ponajzl report no relevant financial disclosures.