UW HEALTH SPORTS REHABILITATION Rehabilitation Guidelines for Patellar Realignment The knee consists of four bones patella that form three joints. The femur is the large bone in your thigh which Trochlea attaches by ligaments and a capsule (groove for patella) to your tibia, the large bone in your shin. Next to the tibia is the fibula, which runs parallel to the tibia. The Femur patella, commonly called the knee cap, is embedded in the quadriceps and patellar tendon and articulates Figure 1 Radiograph of the patellofemoral joint in slight flexion. The lateral aspect of the trochlear groove is normally about 1 cm higher than the medial. with the front of the femur. This is the patellofemoral joint. The patella displacement), especially beyond cap quickly going out of place acts as a pulley to increase the 20° of knee flexion. People who during a sport related movement). amount of force that the quadriceps have a shallow trochlea are more The most common mechanism for muscle can generate and helps direct susceptible to patellar instability. an initial dislocation is a forceful the force in the desired upward inward rotation of the knee on a direction. The patella sits in a groove Proper stabilization of the patella planted foot. The radiograph below on the end of the femur called the is also affected by the soft tissue is that of a 12 year-old-boy in the trochlear groove. This groove varies structures (ligaments and muscles) emergency room after such an in depth from person to person. surrounding the knee. The medial injury (Figure 2). While the knee flexes (bends), the patellofemoral ligament (MPFL) patella travels down the groove and is a continuation of the deep as the knee extends (straightens) it retinaculum and vastus medialis moves up the groove. As the patella oblique (VMO) muscle fibers (inner travels up and down in the femoral portion of the quadriceps muscle) groove it maintains a congruent on the inside of the knee. These boney alignment. This patellar structures provide a significant movement in the femoral groove is force (near 60% total) against lateral often referred to as patellar tracking. displacement of the patella, as their force is directed inward or There are several structures that medially. The MPFL is the primary work together to keep the patella restraint to lateral displacement of aligned and stabilized in the femoral the patella during the first 20-30° groove properly, specifically to of knee flexion. This ligament is prevent the patella from excessive a passive stabilizer and extends lateral movement. The lateral aspect Figure 2 Radiograph of the knee, arrows show from the upper inner side of the of the trochlear groove is normally the laterally dislocated patella patella to medial aspect of the about 1 cm higher than the medial femur. The patellomeniscal ligament which helps to keep the patella in and retinaculum also contribute Often times the patella will go the trochlear groove by providing a over 20% of the restraining force. back in to place (or relocate to buttress on the lateral side (Figure These ligaments can be injured the groove) as the knee is gently 1).This provides the main resistance and torn with an initial acute straightened. In this case the patient to lateral patellar translation (which traumatic patellar dislocation (knee was unable to straighten his knee is the most common direction of The world class health care team for the UW Badgers and proud sponsor of UW Athletics UWSPORTSMEDICINE.ORG 621 SCIENCE DRIVE • MADISON, WI 53711 ■ 4602 EASTPARK BLVD. • MADISON, WI 53718 Rehabilitation Guidelines for Patellar Realignment 16 years-of-age was found to be 43 per 100,000. This incidence lowers to Q angle 31 per 100,000 in the second decade of life, followed by 11 per 100,000 in Line to anterior the third decade and even further to superior iliac spine 1.5-2 per 100,000 in those between Center of patella 30-59 years of age. People with recurrent dislocations of the patella often have anatomical variations or malalignment including patella alta or a higher quadriceps “Q angle” (Figure 3), which predispose them to instability. Patella alta describes a Tibial tubercle high-riding patella which engages the trochlea later in flexion than normal, giving the patella less boney stability. Many options exist for treating patellar instability. Rehabilitation is typically recommended following Figure 3 Diagram representing the “Q” angle of the knee an initial dislocation; however, recurrent dislocation is reported to be and his patella remained dislocated to hip weakness or pronated (flat) as high as 48% with non-operative laterally. Note on the radiograph that feet. Patellofemoral stress syndrome treatment. Operative treatment is there is no overlap of the femur and (knee cap pain) and patellar typically performed on those with an patella. An individual can also have instability result from a deviation in underlying, predisposing anatomical atraumatic instability. In this situation the normal tracking of the patella. variations/malalignment as noted the instability is more likely to be a Most often abnormal tracking results above. Operative treatment is also partial dislocation or subluxation and in lateral positioning of the patella performed on people who have had not created by a large forceful one (toward the outside of the knee). reoccurring dislocations, as these time injury. People with atraumatic Lateral displacement can occur from individuals typically have continued instability usually have predisposing the femur rotating inward or the apprehension and progressive joint factors that alter their normal patellar patella being pulled outward. This damage. Specific operative treatment tracking. The alignment of the pelvis can happen as a result of injury or is selected based on the particular and femur can affect patellar tracking. repetitive stress. Instability can occur needs of the individual including The alignment of the pelvis and as a mild subluxation (slight loss of extent of malalignment, individual’s femur can be structurally altered joint alignment), or as a complete age, level of activity, ligamentous based on a particular individual’s dislocation (Figure 2). Patellar injury (MPFL) and joint condition. angle of the quadriceps muscle, also dislocation typically involves a strong Examples of procedures used include known as “Q angle”. The “Q angle” quadriceps contraction combined with proximal realignment, MPFL repair is formed by the superior line of the a flexed and valgus knee position and or reconstruction, lateral release quadriceps pull (from the hip) and an internally rotated femur relative to and distal realignment. Proximal the patellar tendon (insertion onto the the tibia. In sports this often occurs realignment alters the medial-lateral front of the tibia) as they intersect at when an athlete plants his/her foot position of the quadriceps muscle the patella (Figure 3). to pivot and the knee turns inward to the patella through appropriate while the upper body and hips are manipulation of the tissues at or The alignment of the pelvis and turning outward. Annual incidence of above the level of the patella. An femur can also be functionally altered patellar dislocations in people under incision is made over the knee and in a weight bearing position due specific procedures include lateral 2 UWSPORTSMEDICINE.ORG 621 SCIENCE DRIVE • MADISON, WI 53711 ■ 4602 EASTPARK BLVD. • MADISON, WI 53718 Rehabilitation Guidelines for Patellar Realignment Distal realignment is often done phase there will be a strong emphasis to reduce the “Q angle”. This is on strengthening throughout the performed through an incision over entire leg and core. In the final stages the knee in which an instrument to of rehabilitation, the focus will be on cut the tibial tubercle (the boney control of sport specific movements, prominence on the top of the tibia such as change of direction and where the patellar tendon attaches) rotational movements. The UW is used. This is called an oteotomy. Health Sports Medicine rehabilitation The basic purpose of this type of guidelines below are presented in a osteotomy is to move the tibial criterion based progression. General turbercle medially (toward the inside). time frames are given for reference The type of osteotomy performed will to the average, but individual determine how much of this bone patients will progress at different will be cut. Because of this difference rates depending on their age, there will also be subsequent associated injuries, pre-injury health differences in when these patients can status, rehabilitation compliance and begin weight bearing. The patellar injury severity. Modifications in the tendon and bone which was cut is specific time frames, restrictions and Figure 4 Lateral radiograph of the knee showing a distal realignment to reduce the “Q” then moved medially which alters the precautions may also be made to angle by moving the tibial tubercle medially. position of the patella. The bone is protect healing tissues based on the reattached in this new position to the specific surgical repair/reconstruction retinacular release (lengthening the tibia with screws (Figure 4). procedure performed. structures on the outside of the A quality post-operative rehabilitation patella), VMO advancement and program is essential to having a MPFL repair and reconstruction successful outcome from a patellar (shortening the muscle or ligaments stabilization procedure. The goals on the inside of the patella). This of rehabilitation will initially