ACL injury and surgery : aspects on function, muscular morphometry and effusion

Abstract

Background: ACL injury and reconstructive surgery, globally and in Sweden, has an established orthopedic treatment course. Reconstruction usually is performed on indication of knee instability after attempting an intensive course of rehabilitation. In some occasions reconstruction is performed on indications of the work- or athletic demands on the individual knee. Physical activity levels may vary widely between people in need of ACL reconstruction (ACLR), but injured people in need of surgery have in common after injury and rehabilitation that they cannot optimally function at their desired activity level. Rehabilitation strategies after both injury and surgery aim to restore strength and function to the fullest. Every-day normal, simple functions like gait may in the long run suffer from the consequences of the joint trauma, effusion and diminished muscular capacity. Years of strength and function deficits can be detrimental. The research covered in the spectrum of this thesis investigates gait adaptations after injury, thigh muscle cross-sectional area and its associations to various outcome variables as a consequence of injury and surgery, and knee joint effusion factors associated with injury and surgery.

Aim: In order to comprehensively analyze effects of ACL injury and reconstructive surgery the investigations had the following aim: To compare gait patterns of chronic ACL injured subjects with healthy control subjects (study I). To analyze changes in muscular morphometry before and one year after ACL reconstruction and relate changes over one year to outcome variables one year after ACL reconstruction (study II and III). To analyze presence and effects of knee joint effusion before and three months after ACL reconstruction, and to investigate if postoperative brace regime affects presence of effusion (study IV). To analyze if a postoperative brace affects general outcome one year after ACL surgery with hamstring graft (study III and IV).

Methods: Three-dimensional gait analysis and electromyography (EMG) was used to study gait parameters and muscle activity-patterns of non-operated ACL copers, who had been injured for at least one year, and of a control group. In another cross-sectional study, ACL-injured who were scheduled for ACL reconstruction were examined with computed tomography (CT) to analyze thigh muscle cross-sectional area (CSA) of the quadriceps, semitendinosus, semimembranosus, biceps femoris, gracilis and sartorius muscles. A randomized controlled trial was then initiated with ACL injured and subsequently reconstructed patients. These patients were randomized into two groups with a postoperative treatment alternative with or without a brace for the three initial weeks after surgery. A group of the randomized subjects were included in a prospective investigation on the effects of injury and surgery on muscular morphometry (CSA) before and one year after surgery. The randomized controlled trial investigated effects of injury and surgery on presence of effusion before and three months after surgery as detected by computed tomography (CT). Clinical, subjective and functional parameters, before and one year after surgery, were correlated to the findings.

Main results: Results show that ACL injured copers, although functioning at above normal activity level, display aberrant muscular activity patterns in gait, but that gait parameters are otherwise similar to controls. ACL injured subjects scheduled for ACL reconstruction show quadriceps CSA ratio deficits of the injured leg, which are comparably larger when the right knee is injured. Women have preoperative hypotrophy of semimembranosus. Thus, effect of ACL injury on muscle size differs between left- and right-sided injuries and sex. ACLR subjects show unchanged quadriceps CSA ratio deficits of the reconstructed leg at the postoperative one-year follow-up. These subjects also show gender-specific patterns of biceps femoris and semimembranosus muscular hypo- and hypertrophy over time before to after surgery. There is no effect of a postoperative brace on any of the investigated clinical, subjective and function or CT effusion parameters. Predictors of presence of knee effusion at three months after ACL reconstruction are a prior meniscus injury, higher Tegner activity level before the injury and a higher Lysholm score at baseline/ before surgery.

Conclusion: This thesis provides results from investigations closely related to function and rehabilitation: Long time ACL injured subjects display aberrant muscular activity patterns in gait. Women and men have a different response to the ACL injury and subsequent surgery regarding muscular morphometry effects, i.e. muscular CSA, before and after ACLR. The effect of ACL injury may also differ for the right and left limb. Prior meniscus injury may delay knee joint homeostasis, with regards to presence of effusion, after initial injury as well as after ACLR. A postoperative brace is not necessary after ACL surgery with semitendinosus-gracilis (ST/G) graft, since no associations can be found which affect presence of effusion at three months and thus improved knee homeostasis, nor regarding clinical and functional variables at one year after surgery.