Postoperative rehabilitation of the multiple-ligament reconstructed knee

Phase I: 0–6 weeks 

The immediate postoperative course for all protocols includes 6 weeks of strict nonweight bearing with crutches. In addition, the patient utilizes a long-leg hinged brace that is locked in full extension. This position has been found to minimize forces on the PCL1 and ACL.2 There has been some support of early range of motion (ROM) after multiple-ligament reconstruction;3, 4 however, several of the subjects still required intervention for motion loss. Fanelli et al reported that restricting ROM minimized limited deleterious effects on the healing grafts, and that an extremely low number of patients required manipulation for loss of motion or arthrofibrosis.5 Nonetheless, the effects of immobilization are a concern; therefore, the period of complete immobilization is only 3 weeks. Patella mobilization is also instituted to minimize restrictions and any motion loss that could be associated with limited patella mobility. It has been our experience that no detrimental effects on the articular cartilage occur with this approach. At the end of the third postoperative week early, passive ROM is initiated. This is performed out of the brace for approximately 5 to 10 minutes 3 to 4 times per day. The patient is cautioned about forcing excessive motion; however, obtaining 90° of knee flexion by the end of postoperative week 6 is encouraged.

Quadriceps atrophy is a major concern after all surgical procedures to the knee. With a 6-week period of relative immobilization and nonweight bearing, this concern is magnified. Isometric quadriceps exercises are employed immediately, and this is often supplemented with electrical stimulation. This modality has been shown to augment quadriceps contraction and facilitate an earlier return of strength.6 Pain and swelling also contribute to quadriceps inhibition. To control these factors and for patient comfort, a continuous cold unit is often employed. The pads for these units are incorporated into the postoperative dressings, but do not directly contact the skin. Protective, antibacterial liners are available to minimize the risk of infection and to protect the dressings from becoming damp. Once the patient is able to demonstrate a strong, visible contraction of the quadriceps, and can perform strict straight-leg raising in the brace, the modalities are discontinued.

With the knee maintained in full extension for the majority of the first 6 weeks, patients often develop hamstring pain and tightness. Therefore, patients are instructed in gentle hamstring stretching; however, vigorous stretching is avoided to minimize posterior shear forces created by the hamstrings. There may also be some discomfort at the incision or arthroscopic portal sites. The patient is advised to perform gentle scar massage once all sites are fully healed.

Phase II: 7–12 weeks 

At the end of the sixth postoperative week, the long leg brace is opened fully to permit ROM and may be removed at night. The patient begins weight bearing of 25% body weight. Weight bearing continues to increase by 25% body weight in a progressive fashion until the patient is full weight bearing at the end of postoperative week 10. Within this same time frame, passive ROM is also increased, guardedly, because flexion greater than 90° places high forces on PCL grafts.3 ROM goal of 0° to 90° by the end of postoperative week 9 is encouraged. Conversely, full passive extension is encouraged immediately to avoid potential flexion contractures. By postoperative week 10, graft healing should be sufficient to allow ROM beyond 90°, and the patient is encouraged to achieve flexion to 120° by the end of postoperative month 3. To facilitate flexion, stationary biking is often employed at this time. Although these motion goals are given as guidelines and to gauge progress, the patient is advised to avoid aggressive ROM and rapid gains in motion. It has been our experience that those patients who make slow, steady gains in motion have less laxity and better outcomes.

Once the patient has attained full weight bearing, closed-chain exercises are implemented. In general, a closed kinetic chain occurs when the distal segment is fixed. Lutz et al7 noted a decrease in shear forces at the tibiofemoral joint during closed-chain exercises, which was attributed to the axial orientation of the applied force as well as to muscular co-contraction. Initially, these exercises are performed with only body weight for resistance; however, as strength improves, progressive resistive exercises are instituted. The patient performs all closed-chain exercises in a range of 0° to 60°. Wilk8 has shown that quadriceps and hamstring muscle ratios are similar during the first 60° of flexion, minimizing tibial translation in anterior or posterior directions. Some of the exercises employed during this phase include leg press, squats (to 60° only), and lunges. Because trunk flexion increases the posterior shear forces,9 the patient is advised to perform the exercises in a neutral position. To maintain cardiovascular fitness, rowing machines, stair-climbers, and rapid walking on a treadmill may also be instituted.

Balance and proprioception training activities are initiated as an adjunct to closed-chain exercises. This incorporates single-leg stance activities that the patient can also practice at home in front of a mirror. Pool walking (if available) may also be a useful adjunct during the initial phase of weight bearing. It allows for gentle resistance and proprioceptive training in an environment that minimizes the forces of weight bearing.

Phase III: 4–6 months 

At the beginning of the fourth postoperative month, the ROM goal is 0° to 120° with gradual progression to full ROM. Flexion limitations of 10° to 15° are not uncommon, but may resolve over time. Residual flexion deficits of 10° or less can persist; however, this rarely results in any functional limitation and may result in less stress on the PCL graft because these fibers are most taut in end-range flexion.3 If active ROM of greater than 90° has not been obtained by this phase, manipulation under anesthesia and/or possible arthroscopic debridement may be considered.

Isolated quadriceps and hamstring exercises are incorporated at this time. Resistance is kept at minimum levels until the patient demonstrates adequate control through the available range. Closed-chain exercises are progressed to patient’s tolerance. At the end of the fourth postoperative month, straight-line jogging is initiated assuming they are able to demonstrate functional strength that is 70% or greater of the uninvolved side. This is commonly assessed via single-leg hop testing as described by Barber et al10 Once allowed to run, the patient is advised to begin with a fast walk that is gradually progressed to a mild jog. As tolerance improves, the patient advances to a more consistent jogging pace.

At the end of the fifth postoperative month, an initial isokinetic assessment is obtained. Higher velocities are employed to minimize shear forces.11 Quadriceps and hamstring deficits of 20% or less are desired before allowing the patient to begin sport-specific activities. The patient is also fitted with a combined instability functional brace to permit more aggressive agility drills. During this time, the patient is monitored carefully for signs of pain, swelling, or increased laxity. At the end of the sixth postoperative month, the patient is allowed to return to sports or heavy labor assuming specific criteria are met. These include:

Phase I: 0–6 weeks 

The treatment principles during this phase are similar to those after ACL/PCL reconstruction. Strict nonweight bearing is crucial, especially if the patient’s normal alignment favors a varus component. Motion is restricted primarily for protection of the posterolateral corner. A split biceps tendon tenodesis is commonly employed to reconstruct the PLC, anchored by a screw and washer. Repetitive motion could potentially result in splintering or fragmentation secondary to microtrauma, thus compromising the integrity of the repair. The patient is also advised to avoid external rotation of the involved lower extremity to minimize any static stretch to the PLC. Quadriceps strengthening, patella mobilization, and gentle hamstring stretching exercises are routinely employed during this phase. All patients are advised to avoid resting positions that place varus forces on the knee.

Phase II: 7–12 weeks 

At the end of the sixth postoperative month, the patient begins weight bearing of 25% body weight that continues to increase by 25% body weight in a progressive fashion, until full weight bearing is attained by the end of postoperative week 10. The hinged brace is unlocked to permit ROM, and this is progressed to 90°; however, the patient is advised to avoid assisting with the hamstrings to minimize posterior shear forces. Techniques to assist ROM include placing the involved extremity on a step and leaning the body forward to promote knee flexion. In addition, patients may sit on a chair or stool with wheels, block the involved extremity against an immovable object, and roll forward. A similar technique can be accomplished on a rowing machine.

With the brace opened, active open-chain quadriceps exercises are initiated in a range of 60° to 0°. It has been shown that open-chain knee extension produces anterior tibial translation between 0° and 60° of flexion.12, 13, 14, 15, 16 Beyond 60°, quadriceps activity results in minimal tibial translation until approximately 70° to 75° of flexion. The point at which quadriceps contraction produces neither anterior or posterior tibial translation has been termed the “quadriceps neutral angle.”17 The specific angle at which this occurs encompasses a wide variance within the population. Nonetheless, at flexion angles greater than the quadriceps neutral angle, quadriceps activity will produce posterior tibial translation of tibia due to the posterior orientation of the quadriceps tendon.17 The primary concern during open-chain exercises is the high level of reaction forces at the patellofemoral joint. Hungerford and Barry18 determined that peak forces occurred at 36° during open-chain knee extension. Consequently, high levels of resistance are avoided with these exercises.

Once the patient has achieved full weight bearing, closed-chain exercises are performed in a range of 0° to 60°. These are performed with body weight initially and are progressed to include resistive exercises in accordance with patient tolerance. Again, it is crucial to perform these exercises with the trunk in neutral to avoid the posterior shear forces that occur with trunk flexion. Exercises are performed in the brace until this is discontinued near the end of the twelfth postoperative week.

Phase III: 4–12 months 

There are many similarities to the ACL/PCL reconstruction at this stage. One variance is that the patient is immediately placed in a functional brace once the long leg brace is discontinued. As patients progress through the postoperative regimen, they are closely monitored for varus, posterior, and posterolateral laxity. Several methods have been described to assess posterolateral instability.19, 20 One such method is the prone external rotation test. The test is performed at both 30° and 90° of knee flexion. The feet are externally rotated with equal force, and the degree of external rotation of the foot is assessed and compared with the contralateral side.19 If external rotation is increased at 30° but not at 90°, then the PLC has been compromised. An increase in external rotation at both 30° and 90° indicates damage to both the PLC and PCL. Posterior drawer testing is also performed routinely to assess the integrity of the PCL graft.

Progression to jogging, sport-specific activities, and return to sports are based on the achievement of specific strength and ROM criteria outlined previously. Return to unrestricted activity usually occurs some time after the end of the sixth postoperative month, and the patient is encouraged to utilize a functional PCL brace for the next 12 months. Patients are also encouraged to return for re-assessment at 1-year intervals to determine long-term functional outcomes. At the yearly follow-up, patients are evaluated by stress radiography, knee-ligament arthrometer, and through ligament rating sheets.

Phase I: weeks 0–6 

As previously stated, the initial 6 weeks of the postoperative recovery changes little. Phase I after ACL/PCL/PLC reconstruction essentially mimics that of ACL/PCL reconstruction. Patient education regarding resting positions of the knee is critical because maintaining the leg in an externally rotated position may place stress on the posterolateral structures. Unfortunately, this position is often one of comfort as well as a natural alignment of the extremity when lying supine. In addition, when gentle ROM is initiated out of the brace at the end of postoperative week 3, strict neutral alignment is essential to minimize forces on the PLC. Passive ROM within these restrictions may be accomplished in several ways. If the patient has access to a wheeled chair and a desk or table, they can block the involved foot against the table or desk and gently roll themselves toward it. They maintain this stretch for 3 to 5 seconds, relax, and repeat 10 to 15 times. A second technique involves placing the involved leg on a 6- to 8-inch step and, while utilizing the crutches, the patient can gently rock the body over the leg. This may involve a minimal amount of weight bearing; however, this is performed for short periods only, even though it may be repeated several times throughout the day. Finally, a stationary bike may be utilized in a pendulum fashion with the contralateral leg supplying the majority of the force. As with the other protocols described, techniques to maintain patella mobility and muscle tone are included during this initial phase. Scar massage is also encouraged if necessary.

Phase II: 7–12 weeks 

Similar to the previous protocols, the patient is allowed partial weight bearing (25% body weight), and the long leg brace is opened at the beginning of postoperative week 7. Weight bearing is advanced in a progressive fashion of 25% body weight over the next 3 weeks so that the patient is full weight bearing at the end of postoperative week 10. ROM guidelines are similar to the other procedures, that is, 90° by the seventh week and 120° somewhere between the 10th and 12th postoperative weeks. Stationary cycling is implemented on a routine basis and closed-chain strengthening exercises are added once the patient has attained full weight-bearing status. Proprioceptive training is also essential once the patient is full weight bearing because this is likely to be altered secondary to prolonged nonweight bearing in association with the period of immobilization. If available, aquatic therapy can be a useful adjunct to advance ROM and gait in an environment that minimizes the forces of weight bearing. Isolated quadriceps and hamstring exercises are avoided during this time; however, emphasis is placed on progressing the closed-chain exercises as well as on refining gait mechanics. Once the long leg brace is discontinued, the patient is immediately fitted with a combined-instability brace. This brace is utilized for weight-bearing activities only, to provide varus and valgus protection. The benefits of bracing as well as its limitations will be discussed later in this article.

Phase III: 4–12 months 

Progression of exercise intensity is the emphasis between the third and fourth postoperative months. This may include walking lunges (0° to 60° only) with resistance, stair-climbers, elliptical trainers, and fast-paced walking on a treadmill or a track. Isolated quadriceps and hamstring exercises are implemented at the beginning of postoperative month 5 although initially, resistance is kept at a level in which the patient can perform 3 sets of 10 to 15 repetitions without pain or undue fatigue. Straight-line jogging is permitted, assuming the patient is able to demonstrate functional strength that is 70% or greater of the uninvolved extremity. This is often assessed through a single-leg hop test, which has been previously described in the literature.10 When jogging is permitted, the patient is advised to begin with a fast walk and gradually progress to a light jog. The patient returns to walking if there is pain, fatigue, or an altered running gait. As tolerance improves, the patient advances to a more consistent jogging pace. The patient is also encouraged to conduct this running on a track, road, or other predictable surfaces. Strengthening continues as resistance is progressed in both open- and closed-chain exercises.

At the end of the fifth postoperative month, an isokinetic evaluation is obtained. Higher velocities are employed to minimize shear forces11 and to mimic functional activities. Quadriceps and hamstring deficits of 20% or less are desired before allowing the patient to progress to the next level of activity. Once strength is established within the parameters set, the patient is fit with a combined instability functional brace to begin nonlinear running and more aggressive agility drills. When these activities are initiated, the patient is routinely monitored for increased pain, swelling, or laxity. It is not uncommon for the patient to develop some irritation and pain around the hardware sites, especially the lateral fixation screw for the PLC. In addition, there may be some discomfort at the tibia hardware site from the functional brace, occasionally requiring a cut out or protective pad. Strengthening exercises continue to be progressed with the goal of achieving functional strength that is within 10% to 15% of the uninvolved side. A variety of tests may be employed to assess this including single-leg hop for distance, single-leg hop for time, and various agility tests such as cone running and figure 4’s. Proprioception is also assessed on devices such as the KAT and BAPS board, or other single-leg balance and agility tests. Return to sports or heavy physical labor is allowed anytime after the sixth postoperative month, assuming that the previously mentioned criteria regarding strength, proprioception, and laxity are met. The functional brace is utilized for 1 year once the patient is allowed to return to unrestricted activity. This provides protection for a total of 18 months after the surgical date.