Return to play following ACL reconstruction; do we need more time? Part 2

 

The second part of this blog aims to review the more common outcome measures that can be utilised to assess return to play readiness, and how these are integrated into our rehabilitation. This will hopefully give some direction as to maximise our patients’ chance of successful return to play.

 

Time Based Outcomes

A large proportion of the NHS based protocols I have experience with use time as a measure of readiness, so lets first look at this for a current baseline. From a physiological point of view, tissue healing following ACL reconstruction takes time, this is analysed in 3 distinct but overlapping stages; early graft healing, proliferation and ligamentization (Scheffler et al, 2008). The phases of healing have been studied in vitro and in vivo by multiple authors across animal and human subjects (Abe et al, 2003. Blickenstaff et al, 1997. Bosch et al, 1994. Liu et al, 1995, Janssen et al, 2013. Marumo et al, 2005. Papageorgiou et al, 2001) and have generalisable time scales; early – up to week four, proliferation – up to week twelve, and ligamentization – six to nine months. The ‘end point’ for this transformation, however, remains contentious within the literature, with a proportion of these authors reporting that structural differences may remain indefinitely. This evidence supports the incorporation of time scales into our return to play assessment, however graft capability on its own is not sufficient to have successful return to play, yet, needs to be considered if returning to sport prior to six months following surgery.

When time is concerned we also need to remember that the donor site needs to heal, and the inevitable time it takes to regain or improve muscular control. Soft tissue healing times are widely accepted as phases once again, with the final stage being remodeling, this begins to happen around 3-6 weeks post ‘injury’, but continues for 12 weeks plus (Watson, 2015). Then you have the time it takes to develop muscular strength and control, Powers and Howley (2017) report a 4-6-week training period to see true hypertrophy beyond motor unit recruitment. This adds a time factor to our decision process, but does not indicate a readiness for return to play, there are too many other factors involved; previous athletic ability, time from injury to operation, age, gender, number of and intensity of training etc. All of these factors influence the time that RTP could take, reducing the usefulness and generalizability of time as an outcome measure.

The utility value of time was highlighted by Grindem et al (2016), who found that the risk of re-injury reduced by 51% per month until 9 months post operatively, but from 9 months to 23 months post-op there was no change. This in a cohort study of athletes returning to level 1 sport. This study used an objective RTP criteria alongside the time-based measure however. This criterion guided the rehabilitation process which included isokinetic strength and hop performance comparison to the contralateral leg, this needed to be passed for the above data to be true. The participants who did not pass the objective criteria were 83% more likely to re-injure following RTP. These results could fit with work by Marumo et al (2005), showing that ligamentization of the graft is needed along with return in dynamic control, however more research is needed to make such analysis, isn’t that always the conclusion?

 

Goal Based Outcomes

With return to play being quite so contextual and multifactorial, a goal-based criterion makes more sense in my mind. Whilst a single physical test will not be able to assess all athletes in all sports perfectly, it gives a greater indication of ability than time, and if needed, can be tailored to the activity in question.

Isokinetic strength is used frequently in both the literature and clinical practice, with particular focus payed to quadriceps and hamstring strength for ACL reconstructions. A 90% symmetry ratio to the contralateral leg has been recommended in multiple research papers, to increase chance of successful RTP and reduce re-injury following RTP (Osteras et al, 1998. Kyritsis et al, 2016). Furthermore, Grindem et al (2016) reported a 1% reduction in quadriceps symmetry is equivalent to a 3% increase in likelihood of re-injury. The hamstring to quadriceps strength ratio has been suggested as an indicator for re-rupture following RTP as a prognostic indicator (Kyritsis et al, 2016), however little to no further research confirms these findings. All of these studies are cohort studies in elite and high-level athletes, focusing on re-injury rates following RTP, as we have discussed before, is a lack of poor outcome a positive outcome? Within clinical practice I do struggle with this testing, I have no access to dynamometers, nor do we have pressure plates, or even a way to load a patient heavily enough. This lack of equipment forces me to rely on repetitions to fatigue at a given weight followed by calculations, or manual muscle testing which is based purely on perception. This does not make this testing obsolete, however could affect the accuracy and outcomes, this is dependent on your clinical setting and equipment though.

Dynamic control is another measured area of return to play, the battery of hop tests appears to be the most utilised outcome measure for this, whilst in clinical practice is also used to assess general readiness for return to play beyond ACL reconstructions. This battery of tests involves; single leg hop for distance, triple hop, 6-meter timed hop and a cross-over hop (Ross et al, 2002), this has been showed to have good test-retest reliability, although in small population of healthy participants (Ross et al, 2002). This method of assessment was used by Kyritsis et al (2016) and Grindem et al (2016) who showed a vast improvement in re-injury rate if a limb symmetry ratio of 90% was achieved prior to RTP, 3 and 4 times lower respectively. This is reinforced by a systematic review (Webster et al, 2019), where completing RTP criteria at 6 months post-op almost doubled the incidence of successful RTP at 12 and 24 months (44% and 80% comparatively). These results were concluded from a male population of professional athletes in one (Kyritsis et al, 2016), all in non-British participants and relatively small sample sizes, limiting the generalizability of the studies. No studies exist, currently, which negate these issues however.  This method of assessment is easier to utilise in clinical practice though, minimal equipment is required, whilst reliability and accuracy is greater than other related outcome measures, such as y-balance test (Garrison et al, 2015).

My concern with all of this testing though; is 90% of previous/contralateral ability sufficient? It has been documented that this reduces re-injury rates and facilitates positive RTP, however these rates remain less than ideal. The proportion of ‘non-contact’ ACL injuries is high – 70% reported by Griffin et al (2000). This suggests to me that previous control was not sufficient, combine this with Grindem et al’s (2016) finding that each 1% of residual deficit is equal to a 3% increase chance of failure, could we do more? Sadly, no further evidence exists comparing risk of failure to residual deficit beyond pass/fail of a 90% ratio, however I feel this could be a positive direction for further research.

 

In summary then; it appears we need to utilise all assessments available to us as physiotherapists for RTP. The simple addition of a goal-based criterion alongside our current NHS protocols could improve outcomes for our patients significantly. Whether these protocols need a more thorough change though, is yet to be confirmed.

 

 

Reference List:

Abe, S. Kurosaka, M. Iguchi, T. Yoshiya, S. Hirohata, K. (1993) Light and electron microscopic study of remodeling and maturation process in autogenous graft for anterior cruciate ligament reconstruction. Arthroscopy 9(4):394– 405

Blickenstaff, K. Grana, W. Egle, D. (1997) Analysis of a semitendinosus autograft in a rabbit model. Am J Sports Med 25(4):554–559

Bosch, U. Kasperczyk, W. Oestern, H. Tscherne, H. (1994) The patellar tendon graft for PCL reconstruction. Morphological aspects in a sheep model. Acta Orthop Belg 60(Suppl 1):57–61

Garrison, J. Bothwell, J. Wolf, G. Aryal, S. Thigpen, C. (2015) Y Balance Test™ Anterior reach symmetry at three months is related to single leg functional performance at time of return to sports following anterior cruciate ligament reconstruction. International journal of sports physical therapy, 10(5), 602-11.

Griffin, L. Agel, J. Albohm, M. Arendt, E. Dick, R. Garrett, W. Garrick, J. Hewett, T. Huston, L. Ireland, M. Johnson, R. Benjamin K. Lephart, S. Lewis, J. Lindenfeld, T. Mandelbaum, B. Marchak, P. Teitz, C. Wojtys, E. (2000) Noncontact Anterior Cruciate Ligament Injuries: Risk Factors and Prevention Strategies. The Journal of the American Academy of Orthopaedic Surgeons. 8. 141-50. 10.5435/00124635-200005000-00001.

Grindem, H. Snyder-Mackler, L. Moksnes, H.  Engebretsen, L. Risberg, M. (2016) Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med 2016;50:804-808.

Janssen, R. Scheffler, S. (2013) Intra-articular remodelling of hamstring tendon grafts after anterior cruciate ligament reconstruction. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 22(9), 2102-8.

Kyritsis, P. Bahr, R. Landreau, P. Riadh Miladi, R. Witvrouw, E. (2016) Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med 2016;50:946-951.

Liu, S. Yang, R. Al-Shaikh, R. Lane, J. (1995) Collagen in tendon, ligament, and bone healing. A current review. Clin Orthop Relat Res 318:265–278

Marumo, K. Saito, M. Yamagishi, T. Fujii, K. (2005) The ‘‘ligamentization’’ process in human anterior cruciate ligament reconstruction with autogenous patellar and hamstring tendons: a biochemical study. Am J Sports Med 33(8):1166–1173

Osterăs, H. Augestad, L. Tøndel, S. (1998) Isokinetic muscle strength after anterior cruciate ligament reconstruction. Scandinavian Journal of Medicine & Science in Sports, 8: 279-282. doi:10.1111/j.1600-0838.1998.tb00483.x

Papageorgiou, C. Ma,C. Abramowitch, S. Clineff, T. Woo, SL. (2001) A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model. Am J Sports Med 29(5):620–626

Powers, S. Howley, E. (2017) Exercise Physiology: Theory and Application to Fitness and Performance. (10th ed.). New York: McGraw-Hill Education.

Ross, M. Langford, B. Whelan, P. (2002) Test-Retest Reliability of 4 Single-Leg Horizontal Hop Tests. Journal of strength and conditioning research / National Strength & Conditioning Association. 16. 617-22. 10.1519/1533-4287(2002)016<0617:TRROSL>2.0.CO;2.

Scheffler, S. Unterhauser, F. Weiler, A. (2008) Graft remodeling and ligamentization after cruciate ligament reconstruction. Knee surgery, sports traumatology, arthroscopy: official journal of the ESSKA. 16. 834-42. 10.1007/s00167-008-0560-8.

Watson, T. (2015) Soft Tissue Repair and Healing Review. [Online]. [02 March 2019]. Available from: http://www.electrotherapy.org/modality/soft-tissue-repair-and-healing-review

Webster, K. Hewett, T. (2019). What is the Evidence for and Validity of Return-to-Sport Testing after Anterior Cruciate Ligament Reconstruction Surgery? A Systematic Review and Meta-Analysis. Sports Medicine (Aukland, NZ). https://doi.org/10.1007/s40279-019-01093-x