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A systematic review of anterior cruciate ligament primary repair rehabilitation

Published:January 19, 2022DOI:https://doi.org/10.1016/j.jcot.2022.101774

      Abstract

      Background

      Rehabilitation after surgery of the injured anterior cruciate ligament (ACL) is crucial for satisfactory outcomes. Many trials have investigated this process after ACL reconstruction. The treatment of acute ACL ruptures with a repair technique has recently regained interest, although very little information is available about appropriate rehabilitation for such patients. The objective of this review was to evaluate studies on rehabilitation following ACL repair.

      Methods

      A systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted for patients undergoing a rehabilitation programme after ACL repair. The review has been registered on the International Prospective Register of Systematic Reviews (PROSPERO, Registration number: CRD42020173450). Elements of rehabilitation care we included in our strategy are postoperative bracing, home-based rehabilitation, strengthening exercises, proprioception and neuromuscular training. We searched PubMed, CINAHL, EMBASE, and the Cochrane Library for randomised trials of any form investigating rehabilitation protocols after repair of the injured ACL. Two reviewers independently assessed eligibility of trials.

      Results

      No trials were included. Available literature of lower evidence was included for discussion.

      Conclusions

      No information is available from randomised trials to indicate whether there is any difference between rehabilitation protocols for patients who have undergone primary ACL repair.

      Keywords

      1. Introduction

      Anterior cruciate ligament (ACL) injury is one of the most prevalent knee injuries among young athletes.
      • Hewett T.E.
      • Di Stasi S.L.
      • Myer G.D.
      Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction.
      Most patients with acute ACL injuries are younger than 30, and such injuries therefore result in early onset osteoarthritis.
      • Friel N.A.
      • Chu C.R.
      The role of ACL injury in the development of posttraumatic knee osteoarthritis.
      This posttraumatic osteoarthritis has a significant associated morbidity and healthcare cost.
      • Thomas A.C.
      • Hubbard-Turner T.
      • Wikstrom E.A.
      • Palmieri-Smith R.M.
      Epidemiology of posttraumatic osteoarthritis.
      In the United States alone, there are estimated to be between 120,000 and 400,000 ACL reconstructions per year.
      • Gagliardi A.G.
      • Carry P.M.
      • Parikh H.B.
      • Traver J.L.
      • Howell D.R.
      • Albright J.C.
      ACL repair with suture ligament augmentation is associated with a high failure rate among adolescent patients.
      Fixed object high-impact rotational landing sports such as gymnastics and obstacle course racing as well as athlete-to-athlete contact sports are thought to result in the highest rates of ACL injury.
      • Montalvo A.M.
      • Schneider D.K.
      • Webster K.E.
      • et al.
      Anterior cruciate ligament injury risk in sport: a systematic review and meta-analysis of injury incidence by sex and sport classification.
      The current gold standard of treatment for ACL rupture is reconstruction performed soon after injury to limit further meniscal or cartilage damage.
      • Gagliardi A.G.
      • Carry P.M.
      • Parikh H.B.
      • Traver J.L.
      • Howell D.R.
      • Albright J.C.
      ACL repair with suture ligament augmentation is associated with a high failure rate among adolescent patients.
      Repair of the deficient ACL was first described by Robson in 1895.
      • Robson A.W.M.
      VI. Ruptured crucial ligaments and their repair by operation.
      This technique avoids donor site morbidity associated with reconstruction, and is thought to better preserve native biomechanics and proprioception.
      • Gagliardi A.G.
      • Carry P.M.
      • Parikh H.B.
      • Traver J.L.
      • Howell D.R.
      • Albright J.C.
      ACL repair with suture ligament augmentation is associated with a high failure rate among adolescent patients.
      ACL repair had fallen out of favour since its popularity in the 1970s and 1980s due to high failure rates.
      • Feagin J.A.
      • Curl W.W.
      Isolated tear of the anterior cruciate ligament: 5-year follow-up study.
      • Sandberg R.
      • Balkfors B.
      • Nilsson B.
      • Westlin N.
      Operative versus non-operative treatment of recent injuries to the ligaments of the knee. A prospective randomized study.
      • Engebretsen L.
      • Benum P.
      • Sundalsvoll S.
      Primary suture of the anterior cruciate ligament. A 6-year follow-up of 74 cases.
      However, more recently it has been noted that ACL repairs of mid-substance ruptures are associated with poor tissue quality and poor healing environments; whereas more proximal avulsions off the femoral footprint may have better outcomes of repair.
      • DiFelice G.S.
      • Villegas C.
      • Taylor S.
      Anterior cruciate ligament preservation: early results of a novel arthroscopic technique for suture anchor primary anterior cruciate ligament repair.
      ,
      • DiFelice G.S.
      • van der List J.P.
      Clinical outcomes of arthroscopic primary repair of proximal anterior cruciate ligament tears are maintained at mid-term follow-up.
      Physical rehabilitation for patients following any ACL injury and surgery essential for return to an active lifestyle. Post-operative care for these patients remains heterogenous. Various outcome measures are used by different centres to assess rehabilitative progress of the post-operative ACL injured knee. These measures include the visual analog scale (VAS) for pain; the international knee documentation committee (IKDC) questionnaire which is a knee-specific subjective patient-reported outcome measure; the knee outcome survey activities of daily living scale (KOS-ADLS); the ACL quality of life (ACL-QOL) questionnaire; the Tegner and Lysholm activity scales; the Cincinnati knee score which covers the domains of pain, swelling, function and activity-level; the KT1000 and KT2000 arthrometers, which are knee laxity testing devices; the Cybex 6000 isokinetic dynamometer measuring knee flexor strength; and the more pragmatic single-limb hop test. Other measures used in some series include early return to function or early return to sport.
      The safety and efficacy of rehabilitation protocols has been studied extensively following reconstruction surgery, however very little data has been published evaluating rehabilitation protocols post-ACL repair.
      • Wright R.W.
      • Preston E.
      • Fleming B.C.
      • et al.
      ACL reconstruction rehabilitation: a systematic review Part I.
      • Wright R.W.
      • Preston E.
      • Fleming B.C.
      • et al.
      ACL reconstruction rehabilitation: a systematic review Part II.
      • Kruse L.M.
      • Gray B.
      • Wright R.W.
      Rehabilitation after anterior cruciate ligament reconstruction.
      The aim of this review is to determine whether there is any evidence to help direct orthopaedic surgeons towards appropriate rehabilitation techniques for their ACL repair patients.

      2. Methods

      A systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted for patients undergoing a rehabilitation programme after ACL repair. We searched PubMed, CINAHL, EMBASE, and the Cochrane Library for randomised trials of any form investigating rehabilitation protocols after repair of the injured ACL. Included search terms were “ACL”, “anterior cruciate ligament”, “repair”, “rehabilitation”, “random∗ trial” and “clinical trial”. Search strategy shown in Appendix 1. PROSPERO registration: CRD42020173450.

      2.1 Inclusion and exclusion criteria

      The level of evidence required for inclusion was determined based upon recommendations by the Centre for Evidence-based Medicine.
      This included high-quality randomised controlled trials (Level-I) or lesser quality randomised controlled trials and prospective comparative studies (Level-II). Lower levels of evidence such as case-control studies, retrospective studies, and case series were excluded.
      Study selection flow diagram is shown in Fig. 1. Two reviewers independently selected the trials that were eligible to be included in the systematic review. Any disagreement was resolved by discussion.

      3. Results

      No Level I–II studies included. Non-randomised and retrospective series were discussed to present the relevant available literature.

      4. Discussion

      This review has highlighted the inadequacy of data available to orthopaedic surgeons when implementing rehabilitation protocols following ACL repair surgery. Indeed to our knowledge, no attempt yet has been made to address this issue with a randomised controlled study. The literature is abundant with equivalent studies following ACL reconstruction, however given the reported advantages of proprioception and more physiological knee biomechanics in repaired compared with reconstructed ACL injured knees, appropriate rehabilitation techniques should be investigated. In order to validate accelerated rehabilitation protocols and early return to sports further evidence is needed.
      ACL repair, rather than reconstruction, has gained favour in recent years with a limited amount of evidence to support its outcomes. Some authors are opting for arthroscopic primary repair of proximal ACL tears with at least good tissue quality, but suggest the technique is contra-indicated in mid-substance or chronic tears with poor tissue quality.
      • DiFelice G.S.
      • van der List J.P.
      Arthroscopic primary repair of proximal anterior cruciate ligament tears.
      Indeed novel techniques are emerging for the repair of ACL tears including dynamic intraligamentary stabilization (DIS) which has been shown to achieve good functional recovery, with failure rates ranging between 4% and 13.6%.
      • Büchler L.
      • Regli D.
      • Evangelopoulos D.S.
      • et al.
      Functional recovery following primary ACL repair with dynamic intraligamentary stabilization.
      ,
      • Ahmad S.S.
      • Schreiner A.J.
      • Hirschmann M.T.
      • et al.
      Dynamic intraligamentary stabilization for ACL repair: a systematic review.
      An Austrian group reported on a high overall complication rate of 57.9% among the fifty seven patients they followed up after DIS in primary ACL repair.
      • Osti M.
      • El Attal R.
      • Doskar W.
      • Höck P.
      • Smekal V.
      High complication rate following dynamic intraligamentary stabilization for primary repair of the anterior cruciate ligament.
      Some studies have reported on their rehabilitation protocol following ACL repair, although no study has specifically investigated the rehabilitation itself. Büchler et al. give a thorough account of their post DIS rehabilitation protocol in five phases which have been summarised below in Table 1
      • Büchler L.
      • Regli D.
      • Evangelopoulos D.S.
      • et al.
      Functional recovery following primary ACL repair with dynamic intraligamentary stabilization.
      However, the authors did not specify the type of brace used and did not clarify when use of the brace could be discontinued, although it appears this was only used as an adjunct to their Phase 1 (day 0–4). Murray et al. also report on their rehabilitation protocol in the Bridge-Enhanced Anterior Cruciate Ligament Repair (BEAR) study.
      • Murray M.M.
      • Kalish L.A.
      • Fleming B.C.
      • et al.
      Bridge-enhanced anterior cruciate ligament repair: two-year results of a first-in-human study.
      This is summarised in Table 2. Included for comparison in Table 3 is a summary the evidence-based post-ACL reconstruction rehabilitation guideline developed by the MOON Group (Multicentre Orthopaedic Outcomes Network).
      • Wright R.W.
      • Haas A.K.
      • Anderson J.
      • et al.
      Anterior cruciate ligament reconstruction rehabilitation.
      Table 1Büchler et al. (2016) Rehabilitation protocol following ACL repair with DIS.
      PhasePhase 1 Days 0–4Phase 2 From day 5Phase 3 From week 3Phase 4 From week 6Phase 5 From week 10
      Isolated ACL repairbrace fixed in extension; allow mobilization, weight-bearing within limits of pain∗active physiotherapy; allowing for free flexion and extensionre-establishing muscle strength and increasing muscle massaim to restore capacity of unlimited control of movement and bilaterally equal leg strengthsjumps and sport specific training
      ∗for patients with concomitant meniscal repair, partial weight bearing with 15 kg was instructed for six weeks.
      (Brace type not specified. Use of brace beyond Phase 1 not specified.).
      Table 2Murray et al. (2019) Rehabilitation protocol following Bridge-Enhanced ACL Repair.
      Post-operative weekFirst 2 weeksWeeks 3–4Weeks 6–12From 3 monthsFrom 6 months
      Isolated ACL repairLocking hinged brace (T Scope; Breg) limit ROM: 0°–50° knee flexion
      For patients with concomitant meniscal repair, brace range was restricted to 0°–40° for first 4 weeks before opening the brace up to 0°–90° of flexion.
      ; partial weight-bearing
      Limited ROM increased: 0°–90° knee flexion; weight-bearing as tolerated with crutchesFunctional ACL brace (CTi brace; Ossur) was recommended and then for cutting and pivoting sport activities for 2 years after surgeryRunning allowedGraded return to sports
      All patients were provided with a cold therapy unit (IceMan; DJO Global) for postoperative use.
      a For patients with concomitant meniscal repair, brace range was restricted to 0°–40° for first 4 weeks before opening the brace up to 0°–90° of flexion.
      Table 3Wright et al. (2015) Rehabilitation protocol following ACL Reconstruction (MOON Guidelines).
      Phase 0: Pre-operativePhase 1: Immediate post-operative First 2 weeksPhase 2: Early rehabilitation Weeks 2–6Phase 3: Strengthening and control Weeks 7–12Phase 4: Advanced training Weeks 13–16Phase 5: Return-to-sport Weeks 17–20
      Normal gaitFull knee extension ROM

      Good quadriceps control (>20 no lag SLR)

      Minimize pain

      Minimize swelling

      Normal gait pattern

      WBAT with crutches
      Full knee ROM

      Improve muscle strength

      Progress neuromuscular retraining
      Maintain full ROM

      Demonstrate ability to descend an 8” step without pain or deviation

      Running without pain or swelling

      Hopping without pain, swelling or giving-way
      Running patterns (Figure- 8, pivot drills, etc.) at 75% speed without difficulty

      Jumping without difficulty

      Hop tests at 75% contralateral values
      85% contralateral strength

      85% contralateral on hop tests

      Sport specific training without pain, swelling or difficulty
      AROM 0–120° flexion
      Strength: 20 SLR with no lag
      Minimal effusion
      Patient education on post-operative exercises and need for compliance
      Educated in ambulation with crutches
      Wound care instructions
      Educated in MOON follow-up expectations
      (specific exercise suggestions have been excluded but are available in the guidelines).
      These studies have demonstrated their rehabilitation methods including postoperative bracing, weight-bearing, and strengthening techniques, however their rationale for choosing such protocols after ACL repair is undisclosed. The rationale for dividing the rehabilitation protocols into distinct phases and the variation in the timing of these phases is also not examined in any study. Whether these phases have relevance to the progression of tissue healing or changes in the inflammatory profile of the synovial fluid environment may be an important topic yet to be elucidated. Comparison of rehabilitation phases following ACL repair with rehabilitation phases following ACL reconstruction may be of little value, given that the strength of the healing ligament is not a consideration in the rehabilitation of ACL reconstruction patients. Surgical techniques are being re-developed, and more technological advances including biological supplementation of repair with bio-scaffolds and stem cells are being explored.
      • Mahapatra P.
      • Horriat S.
      • Anand B.S.
      Anterior cruciate ligament repair – past, present and future.
      We feel that the resurgence of technical innovation in this field should be matched by a scrutinous examination of rehabilitation techniques, and that home-based rehabilitation, proprioception and neuromuscular training should also be evaluated in ACL repair studies, as they have been in trials reporting outcomes following ACL reconstruction.
      Furthermore, it is clear that protocols for rehabilitation following primary repair of the ACL may need to be modified according to whether concomitant injuries to other ligamentous structures occurred at the time of injury, or if other procedures to repair such concomitant injuries are carried out at the time of the primary ACL repair. For example, Büchler et al. described an enhanced protocol with fixed extension in a brace for four days post-operatively followed by a period of partial weight bearing for patients in their cohort who had additional sutured meniscal lesions as well as primary repair of the ACL.
      • Büchler L.
      • Regli D.
      • Evangelopoulos D.S.
      • et al.
      Functional recovery following primary ACL repair with dynamic intraligamentary stabilization.
      Murray et al. adapted their rehabilitation protocol in patients who had concomitant meniscal repair by further restricting the locking hinge brace to a range of motion of only 0–40° for four weeks post-operatively rather than 0–50° for two weeks post-operatively in patients with isolated ACL repair.
      • Murray M.M.
      • Kalish L.A.
      • Fleming B.C.
      • et al.
      Bridge-enhanced anterior cruciate ligament repair: two-year results of a first-in-human study.
      Details of these rehabilitation protocol adaptations are given in Table 1, Table 2 One treatment goal in primary repair of the ruptured ACL is to restore joint mechanics and preserve other soft tissue structures in the knee including the menisci. Adjustments made to rehabilitation protocols following repair of the ruptured ACL according to other soft tissue injury and surgery may therefore be critical to patient outcomes. There is no compelling evidence from this literature review to suggest any method or adaptation is superior.
      Fundamentally, rehabilitation techniques ought to be examined more thoroughly in order that an agreed and standardised programme may be established post ACL repair. The current variability in rehabilitation protocols following repair or reconstruction of the injured ACL render comparison of the two surgical techniques meaningless. Without a standardised rehabilitation protocol it will not be possible to compare outcomes following ACL repair with outcomes following current ACL reconstruction.
      This study demonstrates that there is no compelling evidence to support any of the rehabilitation protocols undertaken. If an accelerated protocol is to be undertaken, which may be appropriate post ACL repair but not reconstruction, then a comparison between this and standard rehabilitation needs to be supported by evidence.

      5. Conclusion

      No information is available from randomised trials to indicate which rehabilitation protocols may be of value for patients who have undergone primary repair of ACL rupture.
      Many aspects of post-ACL reconstruction have been investigated with high level research. However, no such research has been undertaken for patients who have undergone ACL repair. No randomised control trials directly compare rehabilitation protocols following ACL repair. If such a study were not possible, then patients should be entered into a validated rehabilitation protocol following either ACL repair or reconstruction enabling a direct comparison of the surgical techniques without confounding rehabilitation differences.
      It should further be added that modifications of existing rehabilitation protocols may be required for those patients who sustain multi-ligament injuries of the knee, including concomitant meniscal injury for example. These patients may require additional repair surgery, and subsequent protection of that repair which may impact significantly on the rehabilitation protocol they should follow post-operatively for their repaired ACL.
      Methodologically rigorous trials are required to investigate appropriate and valid rehabilitation for these patients. Bracing type and duration, home-based rehabilitation, strengthening exercises, dietary supplementation and neuromuscular training could all impact significantly on patients following ACL repair beyond that studied among ACL reconstruction patients given the purported proprioceptive and biomechanical differences between repaired and reconstructed ACL-injured knees.

      Statement of institutional review board or ethics committee approval of the study protocol

      Not applicable.

      Prospero registration number

      CRD42020173450.

      Author contributions

      GH wrote the draft and conducted review of articles for inclusion.
      HK reviewed and edited the draft and conducted review of articles for inclusion.
      SM edited the draft, reviewed and approved the final manuscript.

      Data sharing

      There are no data in this manuscript.

      Funding/grant support

      This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

      Financial disclosure

      None.

      Declaration of competing of interestCOI

      None.

      Appendix 1. . Search strategy

      Search strategy: " (((repair).ti,ab AND (rehabilitation).ti,ab) AND ((acl).ti,ab OR (anterior cruciate ligament).ti,ab)) AND ((random∗ trial).ti,ab OR (clinical trial).ti,ab)".

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