Postoperative Rehabilitation Concepts

Acute Phase

After injury or surgery, the acute phase is a critical period in which treatment philosophies should be followed that create an environment that protects healing tissue, restores range of motion (ROM), minimises restrictive scar tissue adhesions, normalises muscle activation and reduces muscle atrophy. Timelines of restrictions can vary widely between different injuries and surgeries. It is beyond the scope of this chapter to cover the specific rehabilitation for all pathological conditions of the knee and surgeries discussed in this book. However, key differences related to protection of healing tissues are highlighted in Table 41.1 . Postoperative protocols set the minimum amount of time that must be spent in the acute or protection phase. In addition to time, criteria to progress from the acute phase ( Table 41.2 ) are established for all conditions to determine whether the patient is ready to progress to the next phase.

Restoring ROM as soon as safely possible is a primary goal of the acute phase because of the negative impact joint stiffness has on patient outcomes. ^, Frequent low- to moderate-intensity bouts of ROM activity are recommended to accomplish this without excessively aggravating the inflammatory process. By restoring ROM early, the risk of scar tissue restricting mobility can be reduced. To further aid in reducing scar tissue’s impact on knee function, mobilisation of the patella, quadriceps tendon and patellar tendon is performed. This mobilisation is an important component of rehabilitation given that scar tissue adhesions of this region negatively affect joint mobility and increase patellofemoral and tibiofemoral joint contact pressure. ^,

Quadriceps muscle activation is inhibited after injury or surgery. Initially, open kinetic chain (OKC) isometric and isotonic exercises are used to restore muscle activation and strength because of their value in isolating specific muscle groups and their ability to minimise weightbearing compressive forces on an acutely irritated joint. Potential strain to healing tissues or grafts is a consideration when selecting exercises. Escamilla et al. discussed evidence showing that ACL strain experienced during OKC activity is often not any more than the strain imparted during daily activities such as walking or stairs. A systematic review and meta-analysis investigating OKC quadriceps activity and anterior cruciate ligament (ACL) laxity concluded, with limited to moderate evidence, that protocols including early or late OKC activity compared with closed kinetic chain (CKC)–only activity show no difference in anterior tibial laxity. This information from Escamilla et al. and Perriman et al. would suggest that inclusion of OKC training is generally safe in an ACL population. However, Perriman et al. noted that specific protocols were followed in the studies they analysed and that patellar tendon grafts may be less susceptible to changes in laxity compared with hamstrings grafts.

Although OKC activities in an ACL patient population may be unlikely to result in graft laxity, this may not be the case in the PCL population. It has been suggested that hamstring OKC activities be limited for 16 weeks in this patient population. These results emphasise the importance of using clinical judgement, biomechanics and clinical literature to inform exercise selection according to pathological condition. Tables 41.2 through 41.5 provide guidance as to when certain OKC and CKC exercises are typically appropriate. In general, the early phases of rehabilitation use primarily OKC exercise and then transition to predominantly CKC exercise in the later phases.

Neuromuscular electrical stimulation (NMES) is an effective adjunct therapy shown to accelerate control of the quadriceps muscle contraction, and it is a recommended treatment until muscle activation is normalised. Normal muscle activation is considered achieved in the acute phase when the patient demonstrates the absence of an extensor lag by actively terminally extending the knee equal to the uninvolved side. Given the long-term deficits in activation observed, NMES may be necessary to incorporate with CKC activity in the later phases of rehabilitation. The use of biofeedback in the form of manual cueing or electronic-based visual or auditory feedback have also been shown to facilitate the active contraction of the quadriceps muscles.

In addition to decreased muscle activation, muscle atrophy after injury or surgery causes loss in cross-sectional area and muscle weakness. ^, Muscle weakness can persist for up to 2 years or longer. ^, As previously stated, it is important to integrate quadriceps exercises early in rehabilitation; however, combating this atrophy may be problematic because of the fact that the joint often must be protected (see Table 41.1 ) because of tissue healing, pain and the general level of irritation. These restrictions may make it difficult to place enough stress through muscle and tendon structures through traditional early rehabilitation exercises to reduce muscle atrophy or achieve hypertrophy. However, low-load blood flow restriction (LL-BFR) training is a method that uses a specialised tourniquet to restrict blood flow into the limb. This restriction causes a hypoxic environment ^, and results in a cascade of effects similar to the physiological response seen with heavy load resistance training. Studies on healthy individuals comparing LL-BFR resistance training to heavy-load resistance training reported that the LL-BFR group can achieve results near those of the heavy-load resistance training group. However, given that heavy-load resistance is often not appropriate early in rehabilitation, LL-BFR training can be an excellent option for resisting muscular atrophy and gaining muscle mass ( Figs 41.1 and 41.2 ). ^, Clinical studies on groups after injury and surgery are fewer, but a systematic review concluded that LL-BFR training is superior to standard low-load resistance training for building strength and increasing muscle mass.

Periodisation

After the acute phase, rehabilitation is split into specific phases to target physiological deficits, a form of training called periodisation. These phases target the development of muscular endurance, strength and power. In healthy populations, periodised training is shown to be more effective than nonperiodised training. ^, Clinical studies comparing forms of periodised and nonperiodised training are lacking. However, given the superior outcomes observed in trained and untrained individuals, ^, it is recommended that periodisation be incorporated in rehabilitation RTS programming. ^,

Although both linear and nonlinear periodisation may be appropriate depending on the condition and athlete, linear periodisation is the focus of this chapter. Linear periodisation allows for progressive loading, from low load and high repetitions (reps) in the endurance phase to heavy load and low reps in the strength phase, and finally maximum velocities of movement in the power phase. Further, goals for each phase of periodisation are provided as criteria for patients to meet before advancing to the next stage of rehabilitation. This is done to help ensure patients develop the physiological parameters focused on in each phase, make progress towards RTS criteria and remove strict time-based progression when appropriate.

Endurance Phase

The endurance phase focuses on higher reps of exercises and short rest periods to establish a foundation of local muscle endurance and aerobic endurance ( Table 41.3 ). The high volume of reps per exercise allows patients to practice fundamental movements (e.g., single-leg squats) and rebuild neuromuscular control often lost after injury. Joint tolerance to loading is increased, and patients are instructed in managing load according to joint symptom responses. Table 41.3 outlines an example of endurance phase programming. It is important that programming be adapted according to the patient and surgical precautions.

Several criteria are used to determine whether the patient is ready to progress to the next phase. A single-leg squat endurance test provides the clinician with an indicator that a significant degree of local muscle endurance is developed, and a Quad Index (QI) greater than 70% is used to determine that quadriceps strength is progressing towards eventual RTS criteria. Lateral trunk endurance testing is selected to help ensure conditioning outside of the sagittal plane is not neglected. The anterior reach component of the Y balance test is used as a criterion because it demands the most effort from the quadriceps of the three directions tested. A difference in anterior reach less than 8 cm is not meant to be a research-backed cutoff. Rather, it is meant to be a clinical marker that indicates the patient is progressing towards achieving measurements required in the RTS testing.