title: Functional testing and return to sport following stabilization surgery for recurrent lateral patellar instability in competitive athletes.
abstract: OBJECTIVE
  Medial patellofemoral ligament (MPFL) reconstruction and tibial tubercle osteotomy are commonly used to treat recurrent lateral patellar instability, yet there are limited available data on return to sport (RTS) following these procedures. The purpose of this study is to evaluate patient factors associated with excellent functional outcomes, including successful RTS, following surgical stabilization including MPFL reconstruction in competitive athletes with recurrent lateral patellar instability.
  
  
  METHODS
  Athletes undergoing primary MPFL reconstruction for recurrent lateral instability from 2005 to 2013 were identified at a single institution. Concomitant procedures, such as tibial tubercle osteotomy (TTO), were included. Patient demographic information, including BMI, gender, age, and pre-injury Tegner score, was recorded. In addition, radiographs were reviewed for pre-operative patellar height (Caton-Deschamps index) and trochlear dysplasia (Dejour classification). All patients underwent a standardized rehabilitation/post-operative protocol, with isokinetic strength and functional testing being performed at 6 months post-operatively. Final Tegner scores, RTS status, subjective instability ratings, and Kujala scores were collected at a minimum of 2 years. Chi-squared analysis for categorical variables and Wilcoxon rank-sum analysis for continuous variables were used to determine the relationship between the previously mentioned patient and knee characteristics with isokinetic data, RTS status, or Kujala scores.
  
  
  RESULTS
  Thirty-nine athletes (23 male, 16 female) at a mean age of 17.5 ± 2.9 years (range, 13-26) underwent primary MPFL reconstruction (32 autografts, seven allografts) for recurrent patellar instability with a mean follow-up of 47.0 ± 16.4 months. Sixteen patients (41%) underwent concomitant tibial tubercle osteotomies. Isokinetic data collected at 6 months post-operatively demonstrated mean knee flexion and extension strength deficits of 15.8 ± 10.1% and 21.4 ± 14.3%, respectively, compared to the contralateral leg (p < 0.001 for both). Patients who underwent concomitant tibial tubercle osteotomy (p = 0.04), males (p = 0.01) and those with patella alta (p = 0.04) had weaker 6-month isokinetic testing. Thirty-three of the thirty-nine (85%) athletes were able to RTS at a mean of 8.1 ± 3.9 months. Patients undergoing MPFL with concomitant TTO (p = 0.02) returned to sport at a slower rate. One patient (3%) reported an episode of recurrent dislocation requiring revision surgery. Kujala and Tegner scores at final follow-up were 91.1 ± 6.3 and 6 (range, 4-9), respectively.
  
  
  CONCLUSIONS
  Surgical stabilization including MFPL reconstruction for recurrent lateral patellar instability is an effective procedure for returning athletes to competitive sports. However, strength deficits persist at 6 months after surgery, especially in those undergoing concomitant TTO, which may delay return to sport. Physicians can use these results to counsel patients that return to competitive sports is safe with good clinical outcomes and low rate of recurrence at 4-year follow-up; however, predisposing factors, like a lateralized tibial tubercle, should be addressed if necessary, but athletes should be counselled that a slower recovery and longer return to sport time may be expected.
  
  
  METHODS
  IV.
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA. Krych.aaron@mayo.edu.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Krych
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: O'Malley
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Nick R
authors.initials: NR
authors.lastname: Johnson
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Rohith
authors.initials: R
authors.lastname: Mohan
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hewett
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Stuart
authors.affiliation: Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Diane L
authors.initials: DL
authors.lastname: Dahm
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000534:rehabilitation / Q000601:surgery*; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods*; D031222:Patellar Dislocation / Q000503:physiopathology / Q000534:rehabilitation / Q000601:surgery*; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D011184:Postoperative Period; D011859:Radiography; D012008:Recurrence; D000068958:Return to Sport / Q000502:physiology*; D055815:Young Adult
keywords: Functional testing; Lateral patellar instability; MPFL; Medial patellofemoral ligament; Return to sport