METHODS

In this IRB-approved study, we reviewed prospectively-collected data on patients who underwent ACL reconstruction by fellowship-trained sports medicine orthopaedic surgeons at our academic hospital. Twenty consecutive autograft ACLR patients who had been allowed to return to competitive sports by their surgeon and therapist were matched with 20 control subjects from a healthy, non-injured population. A strap-stabilized dynamometer was used to measure isometric hip abduction (HABD), hip extension (HEXT), hip external rotation (HER), and knee extension (KEXT) strength. Single leg, timed, triple, and crossover hop tests and a timed 60-second single leg step down (SLSD) test were administered using previously described standardized protocols. Data was tested for normality using the Shapiro-Wilk test. Means between groups were compared using a two-tailed t-test, and categorical data was analyzed using the chi-square test. Significance was set at p0.05.

INTRODUCTION

Current return to play guidelines after ACL reconstruction (ACLR) are controversial, and no standardized parameters exist. Readiness for return to sports is usually based on a combination of factors, including surgeon preference, physical therapist assessment, functional tests, and time from surgery. However, recent studies have suggested that ACLR patients may have persistent functional deficits even after returning to competitive sports. The purpose of this study was to investigate the lower extremity strength and functional test performance of ACLR patients who had been cleared to return to sports. 

ACL Reconstructed Patients Have Persistent Hip Strength and Functional Deficits After Return-to-Play

Jeremy M. Burnham MD1, Michael C. Yonz MD1, Darren L. Johnson MD1A, Mary Lloyd Ireland MD1, and Brian Noehren PhD2

1Department of Orthopaedic Surgery and Sports Medicine, College of Medicine, University of Kentucky2Division of Physical Therapy, BioMotion Laboratory, College of Health Sciences, University of Kentucky

RESULTS

Testing was performed on 40 subjects (20 ACLR, 20 control) with a mean age of 24.15 (range 15-45) years. Twenty-two females (55%) and 18 males (45%) participated. Mean time from surgery for the ACLR group was 8.26 months (range 6-14). There were no significant differences in age, gender, BMI, or baseline Tegner activity levels between the two groups. HER strength (p=0.043) was significantly lower in the ACLR group as compared to the controls. Mean number of repetitions in the timed SLSD was significantly lower (p=0.026) for the ACLR group (31.80, SEM=2.6) as compared to the control group (40.05, SEM=2.4). Performance in the single leg (p=0.003), timed (p=0.017), triple (p=0.005), and crossover (0.015) hop tests were significantly worse for the ACL-R group as compared to the control group. No differences were seen in HEXT, HABD, or KEXT strength between groups.

REFERENCES1. Ellman MB, Sherman SL, Forsythe B, LaPrade RF, Cole BJ, Bach BR, Jr. Return to play following anterior cruciate ligament reconstruction. The Journal of the American Academy of Orthopaedic Surgeons. 2015;23:283-296.2. Petersen W, Taheri P, Forkel P, Zantop T. Return to play following ACL reconstruction: a systematic review about strength deficits. Archives of orthopaedic and trauma surgery. 2014;134:1417-1428.3. Mohammadi F, Salavati M, Akhbari B, Mazaheri M, Mohsen Mir S, Etemadi Y. Comparison of Functional Outcome Measures After ACL Reconstruction in Competitive Soccer Players: A Randomized Trial. The Journal of bone and joint surgery. American volume. 2013;95:1271-1277.4. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Second ACL Injuries 2 Years After Primary ACL Reconstruction and Return to Sport. The American journal of sports medicine. 2014.5. Xergia SA, Pappas E, Zampeli F, Georgiou S, Georgoulis AD. Asymmetries in functional hop tests, lower extremity kinematics, and isokinetic strength persist 6 to 9 months following anterior cruciate ligament reconstruction. The Journal of orthopaedic and sports physical therapy. 2013;43:154-162.6. Hettrich CM, Dunn WR, Reinke EK, Group M, Spindler KP. The rate of subsequent surgery and predictors after anterior cruciate ligament reconstruction: two- and 6-year follow-up results from a multicenter cohort. The American journal of sports medicine. 2013;41:1534-1540.7. Thorborg K, Bandholm T, Holmich P. Hip- and knee-strength assessments using a hand-held dynamometer with external belt-fixation are inter-tester reliable. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 2013;21:550-555.8. Shi DL, Li JL, Zhai H, Wang HF, Meng H, Wang YB. Specialized core stability exercise: a neglected component of anterior cruciate ligament rehabilitation programs. Journal of back and musculoskeletal rehabilitation. 2012;25:291-297.9. Brophy RH, Schmitz L, Wright RW, et al. Return to play and future ACL injury risk after ACL reconstruction in soccer athletes from the Multicenter Orthopaedic Outcomes Network (MOON) group. The American journal of sports medicine. 2012;40:2517-2522.10. Hewett TE, Myer GD. The mechanistic connection between the trunk, hip, knee, and anterior cruciate ligament injury. Exercise and sport sciences reviews. 2011;39:161-166.11. Crossley KM, Zhang WJ, Schache AG, Bryant A, Cowan SM. Performance on the single-leg squat task indicates hip abductor muscle function. The American journal of sports medicine. 2011;39:866-873.12. Powers CM. The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. The Journal of orthopaedic and sports physical therapy. 2010;40:42-51.

METHODS

A B C

RESULTS

Table 2: Strength and Functional Tests for ACL Reconstructed (ACLR) Patients Compared to Matched Controls

Figure 1: Demonstration of (A) hip external rotation (B) hip abduction, (C) hip extension, and (D) step-down tests.

A

B

C

A B C D

KEY POINTS

• Hip external rotation strength remains weaker in ACLR patients at time of return-to-play as compared to matched controls.

• Matched controls demonstrated significantly better performance in all hop tests utilized as compared to ACLR patients.

• ACLR patients performed worse on the Single Leg Step-Down test (SLSD) than their matched counterparts.

• More objective measures are needed prior to clearing ACLR patients for Return-to-Play (RTP).

DISCUSSION AND CONCLUSIONS

At a mean follow-up time of over eight months, ACL reconstructed patients who had been cleared to return to sports exhibited deficiencies in hip external rotation strength, SLSD performance, and hop test performance as compared to a matched control group. The worse performance of ACLR subjects on the SLSD test but not KEXT strength test indicate that some ACLR subjects deemed ready for sports may continue to lack the power and endurance needed for successful sports participation. These results suggest that more objective measures should be used when evaluating patients’ return to play readiness.

  No. Age (yrs) Sex BMI Follow-up (months) Graft Type Tegner

ACLR 20 22.85 (15-45)

11 female, 9 male

23.68 (SD=2.83) 8.3 (6-14) 5 HAM-AUTO, 12

BPTB, 3 HAM-AUG 5.75 (SD=1.73)

Control 20 25.45 (21-38)

11 female, 9 male

24.24 (SD=3.41) -- -- 5.75 (SD=0.97)

-- Not Applicable; BPTB: Bone Patellar Tendon Bone; HAM-AUTO:: Hamstring Autograft; HAM-AUG: Hamstring Autograft Augmented with Hamstring Allograft

  ACLR CONTROLS

Tests Mean Mean Difference (vs. ACLR) P-value

Hip Extension 19.92 7.22 22.19 8.94 2.46 0.390

Hip External Rotation 10.29 3.52 12.91 4.34 2.62 0.043*

Hip Abduction 29.35 5.75 29.92 9.76 0.57 0.823

Knee Extension 31.41 12.23 38.24 17.19 6.84 0.155

SLSD (Repetitions in 60s) 31.8 11.57 40.05 10.93 8.25 0.026*

Single Leg Hop (cm) 132.11 36.67 168.01 34.60 35.90 0.003*

Timed Hop (seconds) 3.33 1.99 2.19 0.50 -1.14 0.017*

Triple Hop (cm) 378.85 105.38 476.26 100.58 97.41 0.005*

Crossover Hop (cm) 330.68 106.63 417.81 107.04 83.83 0.015*

* Statistically significant, ** Trend, Standard deviation, Statistically significant differences in bold; SLSD = Single Leg Step-Down Test 

Table 1: Study Population

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*

*

**

DISCLOSURES

Detailed disclosures can be viewed on the “My Academy” app, the final printed program, or at http://www.aaos.org/disclosure. A=Editorial or governing board: Journal of Surgical Orthopaedic Advances, Orthopedics, Orthopedics Today, SLACK, Sports Medicine and Arthroscopy Review; Research Support: DJ Orthopaedics, Smith & Nephew Endoscopy; Board or Committee Member: AOSSM, SOA; Royalties and Paid Consultant: Smith & Nephew Endoscopy

SLSD