Masterclass: LARS - Part II. Rehabilitation Following LARS Procedure.

Returning an athlete following a ‘LARS reconstructed knee’ back to competitive status requires much more than simply restoring muscle strength and range of movement. An integrated approach encompassing full kinetic chain function enhancement is required. Additionally, an in-depth knowledge of strength and conditioning principles and how these apply to the systematic rehabilitation process and the long-term reconditioning of a LARS reconstructed knee is essential. Furthermore, ensuring the athlete remains injury-free requires ongoing management and regular monitoring.

Key considerations

Return to competition following a LARS procedure differs significantly compared to a standard graft repaired knee (see Tracy Ward’s article for guidelines on returning to sport after traditional graft). Due to the unique nature of the LARS reconstruction, time frames are compressed and accelerated. Table 1 below compares the ‘expected’ time frames for return to competition for a LARS reconstructed knee versus a traditional ACL reconstruction. This topic has received a significant amount of media attention in Australia, with some professional Australian Rules Football players returning as fast as 14 weeks post injury.

The primary reason for the delayed return to competition in traditional ACL reconstructed knees with an autograft such as the hamstring or patella-bone-patella graft is the time it takes for the autograft to re-vascularise. Furthermore, the autograft has a harvested site that leads to donor site morbidity. Therefore the graft and the harvest site have to be protected until both have sufficient strength to be loaded. Conversely a LARS reconstructed knee is immediately protected by the nature of the artificial ligament matrix. The remaining ACL stump regrows through the matrix; however the knee is essentially stable during this process.

Stages of rehabilitation

When planning and delivering the stages of rehabilitation programmes , an understanding of the influence of load exposure, load attenuation and force generation is critical to provide clinicians with a clear understanding of the milestones that need to be achieved – and the rate at which they can pursued. The best way to approach the process, therefore, is to stage the approach to high performance and load resilience using a ‘phased’ or ‘milestone-based’ strategy, with each stage feeding into the next. In keeping with the exit-criteria approach, we do not move between stages according to the passage of time, but the accomplishment of functional goals.

The four primary stages of knee rehabilitation following LARS reconstruction are:

1. Protection and healing
2. Restoring muscle strength and range of movement
3. Integrated functional adaptation
4. Sports-specific retraining

The time frame in each stage will depend primarily on the pathology we are dealing with. A simple LARS reconstruction will progress faster than a LARS that has associated meniscal repair, or if the femoral condyles and/or tibial plateau have residual bone oedema. The key objectives for each are discussed in more detail below.

Phase 1 – protection and healing

A critical early intervention following a LARS reconstruction is to protect the joint from further damage and to allow a supportive environment in which healing can take place. Dependent on the injury, this may require bracing, taping or even use of crutches. As soon as possible however, we want to restore normal gait mechanics as this has positive effects on proprioception and muscle activation. An effective way of graduating this is through an altered weight-bearing environment such as a pool.

The importance of removing effusions 

Due to the nature of the arthroscopic surgery to repair a torn ACL with a LARS prosthetic, it is common for the patient to demonstrate a knee effusion post operatively. A knee joint effusion is an excessive amount of fluid within the synovial capsule of the knee indicating that the knee is inflamed or irritated (see figure 1).