Patellar Realignment
Seth Jerabek, MD
Dr. Jerabek or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Stryker, and serves as a paid consultant to Stryker.
Introduction
Patellofemoral dislocation is estimated to account for 2% to 3% of all knee injuries. Females between the ages of 10 to 17 years are the highest risk group. Those who participate in pivoting sports, have patella alta, a high Q angle, a high tibial tubercle to tibial groove (TT-TG) distance, and/or a dysplastic trochlea are at higher risk for instability and dislocation (Figure 49.1). The Q angle is formed by a line bisecting the axis of the patella and the patellar tendon and a line along the shaft of the femur, which determines the vector of pull of the quadriceps. When treated nonsurgically, recurrent dislocations occur at an estimated rate of 15% to 50% depending on activity-level underlying risk factors.
Lateral dislocations occur when the medial patellofemoral ligament (MPFL) ruptures, which is the primary medial patellar stabilizer (Figure 49.2). If the MPFL becomes incompetent, the patella will track laterally and may tilt. This likely increases the risk of dislocation and increases pressure of the lateral patellar facet and lateral trochlea, which could lead to arthritis. Additionally, the bony alignment, including the Q angle and TT-TG distance, affect patellar tracking and stability.
Patients with patellar instability often have chondral or osteochondral injuries leading to crepitus or even locking or catching of the knee. After the acute injury, patients may experience a vague sense of instability of the knee, particularly in sports that requiring pivoting. On examination, the patella is often hypermobile and tracks laterally. Manual lateral subluxation of the patella causes apprehension.
Patients with chronic instability and multiple dislocations often benefit from surgery. However, patients with a single, acute dislocation may be indicated for surgery depending on the presence of a loose body requiring surgery, limb alignment, and underlying risk of further dislocations. Carefully selected patients without dislocation but chronic pain around the patella and distinct clinical evidence of maltracking may also be candidates for surgical realignment if nonoperative measures fail to provide adequate relief.
Surgical Procedure—Patellar Realignment
Indications
Patella dislocation in a young, active patient with abnormal patellar tracking
Loose body requiring surgery
Recurrent instability
Contraindications
Single dislocation with a normal tracking patella and normal bony alignment
Skeletal immaturity
Procedure
Treating patellar instability has been divided into proximal and distal realignment procedures. In both procedures, a knee arthroscopy is often performed to treat a loose body, evaluate the cartilage surfaces, and to assess patellar tracking during knee motion. In proximal realignment, the repair is soft-tissue based, and is often a combination of an MPFL repair, reconstruction, or medial reefing with or without a lateral retinacular release. Distal realignment procedures focus on correcting underlying bony malalignment by using an osteotomy to translate the tibial tubercle in the medial or anteromedial direction to decrease the Q angle, TT-TG distance, and contact pressure at the lateral patellar facet. Distal realignment procedures often incorporate a proximal soft-tissue procedure, such as an MPFL reconstruction and/or lateral release during the procedure. The decision on the best procedure for the patient is dependent on patient anatomy, alignment, activity level, and surgeon preference.
Postoperative Rehabilitation
Introduction
Rehabilitation after patellar realignment will vary from patient to patient and from surgeon to surgeon. It will be based on the reconstruction performed and surgeon preference. It is critical
for the surgeon and therapist to have specific recommendations and open communication regarding bracing, weight bearing, and motion. The following outline is a standard protocol and progression that may be used for both proximal and distal realignments.
for the surgeon and therapist to have specific recommendations and open communication regarding bracing, weight bearing, and motion. The following outline is a standard protocol and progression that may be used for both proximal and distal realignments.
 Figure 49.1 Illustrations of risk factors for dislocation. A, Patella alta: High patella relative to joint line. B, Q-angle: The higher the Q-angle the more lateral force with quadriceps contraction. C, Tibial tubercle to trochlear grove distance. The higher the distance, the more lateral force on the patella. D, Trocheal dysplasia: The trocheal groove is shallow leading to instability. |
 Figure 49.2 Illustration of medial patellofemoral ligament. |
Functional Goals and Restrictions
Goals for the first 2 weeks after surgery include controlling pain and swelling, initiating knee motion, and regaining quadriceps activation. From weeks 2 to 6, the patient is typically in a hinged knee brace locked in extension for weight bearing, but can transition off crutches. The patient can work on regaining motion, and can start muscle activation. At 6 weeks and onward, the patient comes out of the brace and works on regaining full motion and strength. Generally, patients can return to in-line sports, such as bicycling and light running at 3 months, and pivoting sports between 6 and 9 months. However, patients who undergo an osteotomy may have an altered rehabilitation protocol depending on the surgeon’s assessment of fixation and degree of bone healing, especially in the first 2 to 3 months. The rehabilitation goals can be subdivided as below.
Phase 1 (Swelling Control): Weeks 0 to 2
Control swelling with ice and compression
Weight bearing as tolerated with hinged knee brace locked in extension and crutches
Gentle early motion, work on regaining full extension
Quadriceps activation
Phase 2 (Motion and Early Strengthening): Weeks 2 to 6
Weight bearing as tolerated with hinged knee brace locked in extension
Discontinue crutches when comfortable doing so
Maintain full extension and flexion to 120°
Begin quadriceps strengthening
Phase 3 (Normal Gait and Motion): Weeks 6 to 12
Transition out of brace
Regain full flexion
Walk with normal heel-toe gait
Muscle strengthening
Phase 4 (Early Sport Activity): Weeks 12 to 20
Regain full muscle strength
Cardiovascular conditioning
In-line running
Sport-specific training (speed and agility training)
Phase 5 (Full Sport Activity): Week 20 Onward
Return to pivoting sports
Preferred Protocol
Phase 1: Weeks 0–2
Ice or a cooling device should be used for 20 minutes per hour for the first 48 to 72 hours (while awake). Thereafter, ice should be used at least three times per day for 20 minutes per treatment.
Weight bearing as tolerated with hinged knee brace locked in extension and crutches
Supine heel slides: With the patient lying supine, have the patient use the contralateral leg or towel to assist in knee flexion. Hold the maximal bent position until tightness or stretching is perceived and hold for 5 seconds. Then, straighten the knee and repeat, with the goal to get to 90° by 2 weeks. Two sets of 10 repetitions (Figure 49.3)
Sitting heel slides: Sitting in a chair, the patient should slide the heel underneath the chair until maximum flexion is gained, with the goal to get to 90° by 2 weeks. The patient can slide the body forward in the chair while keeping the foot planted firmly on the floor to enhance flexion. Hold for 5 seconds and straighten leg, and repeat. Two sets of 10 repetitions (Figure 49.4).Related posts:
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