Patellar Injury and Dislocation Treatment & Management

Rehabilitation Program

Physical Therapy

During the acute phase of a patellar injury or dislocation, the immediate goals are to reduce inflammation, relieve pain, and stop activities that place excessive loads on the patellofemoral joint. Patients with an acute patella dislocation typically have been evaluated in an emergency department, with radiographic evaluation, and have often had a consultation with an orthopedist to assess for intra-articular pathology. Acute phase management should apply the PRICE principle: protection of the injured joint, relative rest, ice, compression, and elevation to control inflammation.

A study by Maenpaa and Lehto suggested that a period of immobilization may be beneficial. In their study of 100 acute dislocations, patients were divided into 3 treatment groups: plaster cast, posterior splint, and patellar bandage/brace. ^[31] At long-term follow-up, fewer redislocations were noted in the posterior splint group and the cast group than in the patellar bandage group. The first 2 groups had a period of immobility, whereas the bandage group did not. The mechanism of benefit is thought to be the time to heal the disrupted medial structures. The best outcomes were noted in the group initially treated with a posterior splint. The plaster cast group had a longer period of immobilization, and the authors suggested limiting the period of immobilization to 3 weeks to avoid muscle atrophy, knee joint restrictions, and retropatellar crepitation. ^[31]

Quadriceps strengthening is initiated during the acute phase. In the event of acute patella dislocation, these should be static exercises initiated during the period of immobilization. Quadriceps electrical stimulation is an option for muscle re-education if the patient has difficulty activating the muscle secondary to pain. Electrical stimulation may also play a role in the management of knee joint effusion. When dolor, calor, rubor, and edema resolve, the patient may progress to the recovery phase of rehabilitation.

Therapy should also include a protocol for hamstring muscle stretching. Tight hamstring muscles functionally counteract their agonist group, the quadriceps. In general, nonsurgical management is usually between 6 weeks and 3 months in duration, and there is no consensus on the preferred nonsurgical modality. ^[22]  

Surgical Intervention

In the acute phase, surgical interventions are reserved for complicated dislocations with associated fractures. ^[32] The most common site of cartilage injury to the patella occurs as osteochondral fractures of the medial patellar facet or cracks in the central dome of the patella. Cartilaginous injuries are also frequently seen on the lateral femoral condyle. Arthroscopy can repair or remove fracture fragments. However, acute surgical interventions are unnecessary in most cases of patellofemoral syndromes.

Consultations

If conservative management is not effective and the patient still experiences symptoms, consult an orthopedic surgeon. Particular attention should be paid to symptoms of an intra-articular foreign body, such as clicking, locking, or persistent intra-articular knee pain. These may be signs of an occult loose body within the knee.

Other Treatment

General considerations

In the acute phase, protecting the patellofemoral joint involves reducing loads by postural correction, activity modification, and shoe changes/orthotic management if pes planus is present.

Shoe wear and orthotics can prevent excessive hip internal rotation, knee valgus, and subtalar joint pronation, all of which promote lateral patellar tracking.

Inappropriate cartilage-wear disorders can also be resolved by these measures.

Proper foot support helps reduce patellofemoral pain. Proper foot alignment helps correct some biomechanical causative factors due to congenital deformities.

Conservative treatment of acute traumatic patellar dislocations in this fashion has shown good results.

Patellar bracing

Some controversy exists regarding the effectiveness of knee braces with a patella buttress in the treatment of patellofemoral pain and redislocation. Some authors find bracing to be useful primarily for patient reassurance and believe the primary benefit is psychologic in nature. However, other authors support their use both as a pain reduction adjunct in a conservative rehabilitation program that includes quadriceps strengthening and as protection against redislocation and subluxation.

Study results on the efficacy of bracing for patellofemoral pain are highly variable. None of the studies reviewed controlled for the amount of pressure elicited by the brace on identified muscle groups. One study identified a significantly increased sulcus angle through the entire knee flexion range secondary to the brace use. However, the gross tracking pattern did not change, and minute differences in alignment may have influenced joint mechanics to improve patellofemoral pain. Another study found no benefits when braces were worn. Neptune et al found that increasing VMO strength produces more uniform results than those achieved with brace orthotics. ^[33]

The goal of bracing is to restore proper alignment. This occurs either by mechanical inhibition of lateral patella motion with a patella buttress or, as in taping, by a change in neuromuscular recruitment secondary to muscular proprioception. A case study by Shellock et al that evaluated the use of loaded kinematic MRI to evaluate patellar positioning while the patient wore a patellar realignment brace demonstrated a reduction in lateral subluxation at 30° of flexion and a functional decrease in patient pain. ^[34] Additionally, bracing unloads painful structures, keeps the joint warm, provides proprioceptive feedback, and may assist in improving knee extension neuromuscular patterning.

Care must be used in the acute phase, because bracing may aggravate the patient’s acute condition. However, a neoprene sleeve or other knee wrap that provides external compression helps control inflammation. Many braces have a patellar cutout and lateral buttresses to help prevent lateral patellar tracking.

A randomized, controlled trial by Honkonen et al showed that the use of a patella-stabilizing, motion-restricting knee brace for 4 weeks after a traumatic patellar dislocation did not result in a statistically significant reduction in the rate of redislocations. Knee immobilization was associated with greater quadriceps muscle atrophy, reduced knee range of motion, and worse functional outcomes during the first 6 months after the injury. ^[35]

Patellar taping (McConnell method)

The goals of McConnell taping are to restore proper alignment and control pain.

With proper alignment, VMO retraining is initiated. Once taped, patients should note decreased pain when performing painful activities such as stepping down from a stool. The goal of taping is to optimize patellar positioning and facilitate better activation of the medial patellar stabilizers, particularly the VMO. The technique can be taught to patients to perform themselves. Taping is continued until appropriate patellar positioning and tracking is achieved through the rehabilitation process, which includes appropriate activation of the VMO.

A study examined the timing of VMO and VL firing in patients with patellar pain while walking up and down stairs. ^[36] The authors demonstrated that during step-up activities, the VMO in the taped knee fired earlier in the gait cycle, and the VL had no change in the cycle timing. During step-down activities, the VMO in the taped knee fired earlier and the VL fired later. The authors postulated that these timing changes very early in the gait cycle, when the knee is near full extension, may have a beneficial effect on patellofemoral mechanics and promote movement of the patella into the trochlea groove early in flexion. ^[36]

Barefoot running

Barefoot running may reduce patellofemoral joint stress as a result of reduced joint reaction forces. Barefoot runners are more likely to use a forefoot vs a heel strike pattern in the initial loading response, which has been shown to increase ankle eccentric work and simultaneously decrease the loading on the knee joint. ^[37]

Compared with use of neutral running shoes, barefoot running can decrease the peak patellofemoral joint stress by up to 12%. ^[38] This is accomplished through a reduction in the peak knee flexion angle during stance phase and the peak knee extension moment.

Progression from running with neutral shoes to barefoot running should occur in intervals. An athlete who continues to use a heel strike pattern with barefoot running will experience an increase in the ground reaction forces and worsen patellofemoral joint stress. ^[39]

Rehabilitation Program

Physical Therapy

Therapeutic theory goals of nonoperative management of patellar injury and dislocation are to improve patellar tracking. The VMO is an important medial stabilizer of the patella. Inappropriate synergy patterns between the VMO and the VL have been theorized for lateral patellar tracking. The VL is a much larger muscle than the VMO. By overpowering the VMO, the VL may contribute to lateral tracking.

The prevailing theory has been that lateral patellar tracking is associated with VMO weakness. However, research has been inconclusive for VMO weakness as a direct causative mechanism of lateral patellar tracking. A study by Mohr et al examined timing differences between the VMO and VL in patients both with and without patellofemoral pain. ^[40] The authors concluded that the timing differences noted and their relationship to the gait cycle suggest overall quadriceps weakness rather than specific, focal VMO weakness. As such, Mohr et al recommended overall quadriceps strengthening as the basis of rehabilitation strengthening programs. Other authors have also noted that general quadriceps strengthening has demonstrated reductions in lateral tracking irrespective of the mechanism.

The patient should be educated about correct posture and joint preservation at this time. Supportive adjuncts such as taping and bracing are common treatment modalities. Exercises to strengthen the quadriceps muscle (focusing on VMO activation) include quadriceps-setting exercises and straight-leg raises.

Quadriceps-setting exercises are performed with the patient in the supine position. The contralateral hip and knee are flexed to approximately 45° to protect the low back, and the ipsilateral leg is kept in extension. The quadriceps muscle in the extended leg is contracted, and the contraction is held for 5 seconds. The patient then relaxes the quadriceps and repeats the contraction. (Repetitions and sets are gradually increased.) The ankle of the exercising leg must be actively dorsiflexed during the contraction.

Straight-leg raises are performed with the patient in the supine position and the contralateral hip and knee flexed to approximately 45°. The extended leg (the leg to be strengthened) is raised 8-12 inches from the table and is held at that level for 10 seconds. (Repetitions and sets are gradually increased.)

Additional strengthening exercises must be performed for the hip adductors, hip abductors, and hip flexors. Hip adductors are strengthened with the patient lying on his or her side. The leg against the exercise mat is lifted away from the mat and is held for 10 seconds, followed by relaxation. Hip abductors are strengthened with the patient lying on his or her side. The leg away from the exercise mat is lifted away from the mat and is held for 10 seconds, followed by relaxation. Hip flexors are strengthened with the patient in a seated position. Both the knee and hip are held at 90° of flexion, and the leg to be exercised is lifted off the ground and is held for 10 seconds. (Repetitions and sets are gradually increased for all exercises.)

Any physical therapy program for patellofemoral problems must address tightness of the lower-extremity musculature. Reduced flexibility of the hamstrings, hip abductors, and iliotibial band all can increase patellofemoral pain. Additionally, tight gastrocnemius muscles can increase patellofemoral pain.

Medial patellar gliding exercises may loosen lateral retinacular tightness in this stage. Medial patellar gliding exercises are performed with the leg extended. The patient manually pushes the patella medially and holds for a count of 10 seconds.

An important concept in the rehabilitation of patellar dislocation and patellofemoral pain is knee flexion. Initially, any activity that requires greater than 40-45° of knee flexion causes symptoms. Initial rehabilitation programs start with the isometric open kinetic chain exercises described earlier. Early rehabilitation programs should limit all activities that require quadriceps firing with the knee flexed greater than 45°.

Once isometric open kinetic chain exercises are tolerated without discomfort, the rehabilitation program advances to closed kinetic chain exercises (eg, mini squats, lunges, stair climbing). The rectus femoris, VMO, and VL are all strengthened by the mini squats (repetitions and sets modified to the tolerance of the patient). Earl et al found that when isometric hip adduction is performed in conjunction with mini squats, the strength in these muscles increased significantly compared with the control group performing conventional squats. ^[41]

Important goals are to restore ROM in the joint, mobilize soft tissues, and strengthen the surrounding musculature. Lunges and bike riding allow strengthening through a controlled ROM. The patient becomes more active in this phase, and the clinician must screen the patient for exacerbations of symptoms. If symptoms reemerge, the optimal loading zone of the knee and the activity level must be reevaluated. The patient learns activity limits in this phase. Once pain has resolved sufficiently to complete daily activity requirements without exacerbations, the patient can advance to the final phase of rehabilitation.

Advanced rehabilitation programs progress to jogging, running, plyometrics, and sport-specific exercises. Patients must be monitored and must always follow proper technique, as well as learn to properly fire the VMO.

Surgical Intervention

Surgical intervention may be appropriate in 2 different patient populations: (1) those with normal anatomy who experience recurrent dislocation or pain and (2) those with an anatomic abnormality who may benefit from surgical intervention either upon initial acute dislocation or later with recurrence of dislocation or subluxation. ^[42] In general, following acute patella dislocation, patients with normal lower extremity anatomy and without radiographic indications of intra-articular injury are best served by conservative treatment.

Buchner et al compared conservative treatment with surgical repair in patients with acute patella dislocation ^[17] ; patients with radiologic signs suggestive of a predisposition to redislocation were excluded from the study. Results indicated no significant difference between surgically treated and conservatively treated groups in terms of redislocation rate, reoperation rates, level of activity, or functional or subjective outcomes.

When Camanho et al compared 33 patients with acute first-time patellar dislocation who underwent conservative versus open repair of the MPFL, after a mean of 36 months, 8 patients in the conservative group had recurrent dislocations compared with none in the surgical group. ^[43] Additionally, the surgical group had improved functional outcome as measured by the Kujala score. Overall, the investigators evaluated the rates of recurrent dislocations, subluxations, and instability as indicated by a positive patellar apprehension test. ^[43]  Thus, surgical management should be carefully selected for patients who would benefit from it, and risks and benefits of treatment should be discussed. 

Operative choices may be classified into distal, proximal, and combined procedures. Some authors suggest that rigid, distal procedures are associated with increased rates of progressive retropatellar arthrosis but lower rates of redislocation and that dynamic proximal procedures are associated with a lower incidence of arthrosis but a higher risk of redislocation.

Proximal procedures

Medial repair

There are 3 types of primary procedures for medial repair, all of which attempt to recreate an appropriate physiologic mechanism at the knee joint by improving the integrity of the structures that provide medially directed forces on the patella. The techniques include (1) plication of the medial patellar retinaculum, (2) anatomic repair of the MPFL, and (3), plasty surgery of the VMO.

Anatomic and biomechanical studies have indicated that the MPFL and the VMO are the primary restraints to lateral patella translation, particularly early in flexion before full trochlear engagement. An article by Arendt et al suggested that repair or reconstruction of the MPFL needs to be a component of any surgical intervention to control lateral translation of the patella in a knee with demonstrated lateral instability or dislocation. ^[44]  In the past decade, several studies have been published that are in favor of MPFL reconstruction. 

MPFL reconstruction 

Reconstruction has been favored over primary repair because it provides lower recurrence rates. Isolated MPFL reconstruction is indicated for patients with a TT-TG distance of less than 20 mm, normal trochlear morphology, and absence of patella alta. ^[45]  Various allografts have been described including semitendinosus, gracilis, and quadriceps tendons. Similarly, the graft can be fixed to the patella via suture anchors, interference screws, or bone tunnels. Technique and graft choice are usually selected based on surgeon preference and patient anatomy. Similarly, femoral fixation can be achieved many different ways, but the most important aspect is the location of the tunnel. This has been previously described in this article and is referred to as the Schottle point. Aside from selecting the correct starting point, it is important to tension the graft at the appropriate knee flexion. This has been described as between 30º and 45º of knee flexion. 

Lateral release

This procedure involves making an incision of the capsule of the lateral retinaculum to divide it. Lateral release may be performed as either an open or arthroscopic procedure, and it may also include release of the distal VL.

Extending the release too far can cause medial subluxation of the patella; in fact, medial patella subluxation or dislocation is almost always iatrogenic, secondary to an overzealous lateral release. Instead, the goal of this procedure is to facilitate medial motion of the patella into the trochlear groove and/or to level a patella with a large degree of lateral patella tilt.

This procedure has come under extensive criticism, especially as a sole surgical procedure. Anatomic studies suggest that in addition to providing a laterally directed force on the patella, the lateral retinaculum also provides a posteriorly directed force, with the net force being posterolateral. This posterior force component may provide stability as the patella is directed into the trochlea early in flexion.

In a knee with soft-tissue laxity, a lateral release removes one of the forces directing the patella into the trochlea and further destabilizes the knee. Post et al suggested that this problem is accentuated in patients with a large Q-angle. ^[14] In a cadaveric study by Christoforakis et al, the investigators demonstrated that a lateral retinacular release decreased the force needed to displace the patella laterally 10 mm by 16-19% at knee flexions of 0-20°. ^[46] This correlates exactly with the range of flexion in which the laterally unstable knee is most at risk for lateral dislocation.

Arendt et al suggested that a lateral release should only be performed if it facilitates the recentering of the patella by other procedures or when it is specifically performed to address objective lateral patella tilt. ^[44]

Distal procedures

Tibial tubercle transfers

Tibial tubercle transfer was first described by Hauser in 1938 with a medial and distal transplantation of the tibial tuberosity. This procedure was associated with a high rate of arthrosis, reportedly up to 71% of patients, and had a relatively high redislocation rate, reportedly 17-20%. Consequently, medial and distal transplantation of the tibial tuberosity are no longer performed.

Initially, high rates of arthrosis were thought to be secondary to the posterior movement of the tubercle inherent in the original procedure. This realignment makes use of muscular pull to maintain the patella in a central position in the trochlea. In current practice, numerous variations of this procedure are in use, and they are typically performed in conjunction with the proximal procedures described above.

Tibial tubercle transfer procedures are often performed in an effort to correct for an abnormal Q-angle. However, a large variation in norms for the Q-angle is reported in the literature. Arendt et al noted that in many patients, an exaggerated Q-angle at full extension may correct to normal at 90° of flexion, and surgical correction of those knees would lead to overmedialization of the patella mechanism. ^[44]

Currently, the most common tibial tubercle transfer is in the anteromedial direction, as described by Fulkerson in 1983. The indications are increased TT-TG distance (>20 mm), patella alta, and increased tibial tubercle to posterior cruciate ligament distance. These tibial tubercle transfers are usually done in conjunction with MPFL reconsturction. It is important to note that TT-TG should be decreased to around 15 mm and never below 10 mm.

Other surgical treatments

More intensive joint reconstructive surgery

Procedures such as a trochleoplasty, rotational osteotomy for excessive femoral anteversion or external tibial rotation, and even patellectomy may be performed in cases in which both conservative treatment and less extensive surgery have failed.

When Nelitz et al followed 26 knees with severe trochlear dysplasia that underwent trochleoplasty and medial patellofemoral ligament reconstruction at a minimum of 2-year follow-up, patients reported no recurrent dislocations and significantly improved function. ^[47]

Another study by Ntagiopoulos et al reported no dislocations with improvement in functional scores and overall satisfaction at a median follow-up of 7 years in 27 knees with severe cases of trochlear dysplasia and recurrent dislocation that underwent a sulcus-deepening trochleoplasty procedure. ^[48] Additional procedures were selected based on deficiencies, including medial patellofemoral ligament reconstruction (16.1%), vastus medialis obliquus plasty (83.8%), tibial tuberosity distalization (51.6%), tibial tuberosity medialization (67.7%), and lateral retinaculum release (67.6%).

Importantly, these are extensive surgeries with significant morbidity and potentially lifelong functional deficit; as such, they are reserved for patients with severe trochlear dysplasia and anatomic variants. In addition, these operations should be performed by surgeons who have a higher volume of such cases.

Arthroscopic debridement

In some cases, patients may benefit from arthroscopic debridement for symptomatic relief of arthrosis secondary to the patellofemoral instability.

Postsurgical rehabilitation closely follows nonoperative conservative treatment. All surgical procedures are at risk for complications such as medial tracking, arthrofibrosis, reflex sympathetic dystrophy symptoms, hemarthrosis, and rupture of the quadriceps tendon.

Consultations

If the conservative management is not effective and the patient still experiences symptoms, consult an orthopedic surgeon.

Other Treatment (Injection, manipulation, etc.)

Bracing and taping can be continued in this phase to decrease pain and increase activity participation.

Patellar bracing and McConnell taping are viewed as temporary supportive measures whose functions are described in Acute Phase, Other treatment. They should be discontinued when functional activities are performed without pain.

Rehabilitation Program

Physical Therapy

The final phase of rehabilitation emphasizes developing an independence program for the patient. The patient learns how to stretch appropriately, conduct training routines, modify activity, and apply ice after activity routines. Returning the patient to the preinjured functional state often requires progressive functional activity. The rate of progression is limited by the patient’s tolerance. The patient should work toward single-leg standing, deep squatting, and jumping. Once patients are able to adjust activity routines within their optimal loading zones, they are ready to be discharged and only require routine follow-up treatment.

Consultations

If the conservative management is not effective and the patient still experiences symptoms, consult an orthopedic surgeon.

Other Treatment

Manipulation

Wu treated patients who had anterior knee pain, tenderness, quadriceps imbalance, and patellar subluxation with Chinese manipulation. ^[49] The diagnosis was determined by a plain radiography protocol, and his patients were treated with a combination of manipulation and an exercise program. Although his treatment was successful in alleviating symptoms of patellofemoral dysfunction, Wu's study is limited by not having control groups that received either only manipulation or exercise alone. Future studies should take this into account. His manipulation techniques included the following:

• Rolling the metacarpophalangeal joints over the VMO muscle for a deep massage effect

• Circularly kneading the quadriceps with the thenar eminence

• Mobilizing the patella side to side

• Kneading the infrapatellar fat pad

• Peripatellar rubbing with the hypothenar eminences

• Torsion of the tibia on the femur

• Ranging the patella into extension and flexion

• Massaging the gastrocnemius

• Grasping and elevating the patella

• Moving the patella against the resistance of the lateral retinaculum to stretch the latter

Ultrasonography

Therapeutic ultrasonography is an option used by some healthcare professionals to treat patellofemoral pain syndrome. Of the 85 articles Brosseau et al reviewed, only 1 met preestablished criteria. ^[50] The study that met preestablished criteria evaluated 53 patients and revealed that the effects of ultrasound combined with ice massage versus ice massage alone were not statistically significant. Brosseau et al concluded that more studies needed to be performed. ^[50]

Bracing

Bracing and taping can be of benefit for symptoms of patellofemoral dysfunction, as discussed in Acute Phase, Other treatment.

Return to Play

Patients with patellar injury and dislocation may return to play after (1) all symptoms and episodes or exacerbations have resolved and (2) full ROM and preinjury strength have been achieved in the affected limb. The timeline for return to play varies from patient to patient. In a 2000 study, Atkin et al found that at 6 months, 58% of their study population still reported deficits in function. ^[18]

Some variability exists in the time required to return to play, and it depends on multiple factors, including the underlying anatomy and physiology, whether conservative or surgical treatment was used, and the type of surgical treatment performed. In a review article in 2003, Hinton et al suggested that following surgical correction of a patellar injury or dislocation, return to sports can be anticipated to occur 4-6 months after the procedure. ^[51]

Prevention

To prevent patellofemoral knee problems, patients must not exceed the optimal patellofemoral joint-loading capacities. In addition, enhancing quadriceps strength prevents most symptoms and pathologies. Athletes involved in soccer and weight lifting should be especially careful. Studies on prophylactic bracing for patellofemoral dysfunction have thus far been inconclusive. The variability in results from bracing is likely due to the different subtleties of patellofemoral biomechanics in each individual. Each brace fits and affects different muscle groups to different degrees in different individuals.