➢ Major anatomic risk factors for recurrent patellar instability include trochlear dysplasia, patella alta, a lateralized tibial tuberosity, and medial patellofemoral ligament insufficiency.
➢ Acute first-time patellar dislocation may be treated nonoperatively in the absence of osteochondral injury.
➢ Recurrent patellar instability often requires medial patellofemoral ligament reconstruction, with osseous procedures reserved for patients with substantial underlying anatomic abnormalities.
➢ Surgical treatment of patellar instability is complex and should be individualized to address the needs of each patient.
Patellar instability is a common disabling condition that primarily affects young, active patients. The reported incidence of primary patellar dislocation is 5.8 per 100,000 per year, although it may be as high as 29 per 100,000 per year in adolescents1. Recurrence rates following primary dislocation have been reported from 15% to 44%1-3. The purpose of this review article is to provide an algorithmic approach in diagnosing and treating patellar instability in the acute and chronic settings.
Anatomy and Biomechanics of Patellar Instability
Static stability of the patellofemoral joint is provided by both osseous and soft-tissue constraints. Osseous stability is provided by the depth of the femoral trochlea as well as the height of the lateral trochlea. With a dysplastic lateral trochlea or a shallow trochlear groove, the patella can easily subluxate or can dislocate during normal motion4.
Normally, the patella engages the trochlea at 20° of knee flexion. In patella alta, there is a delay in the engagement of the patella in the trochlear groove with knee flexion, which is a substantial risk factor for instability independent of underlying trochlear dysplasia5,6.
The medial patellofemoral ligament, medial patellotibial ligament, medial patellomeniscal ligament, and medial retinaculum and capsule all provide static stability. The medial patellofemoral ligament is the most important static soft-tissue stabilizer. Cadaveric studies have shown that the medial patellofemoral ligament contributes a mean (and standard deviation) of 53% ± 15% of the total resistant force to lateral displacement7-9. The contributions of the other ligaments were found to be 22% ± 9.5% for the medial patellomeniscal ligament, 11% ± 6.5% for the medial retinaculum, and 5% ± 5.9% for the medial patellotibial ligament of the total resistant force7-11. Interestingly, one study demonstrated that the lateral retinaculum provided 10% of the soft-tissue restraint to lateral patellar displacement7.
The vastus medialis obliquus acts as the primary dynamic stabilizer of the patellofemoral joint and has soft-tissue attachments to the medial patellofemoral ligament that likely provide additional stability to the patella11,12. Without the contribution by the vastus medialis obliquus, in cadaveric studies, the pull of the vastus lateralis will dislocate or will subluxate the patella12,13.
The contracture of the lateral retinaculum or excessive tightness of the iliotibial band increases tension on the lateral patellar facet during knee joint motion, predisposing to instability14. Increased femoral anteversion, increased tibial external rotation, and increased genu valgum may also lead to patellar instability15-18.
Clinical Presentation and Evaluation
Acute episodes of patellar dislocation may be the result of direct trauma or may occur as noncontact injuries. Patients may report a sensation of instability or feel a pop. In most instances, the patella will spontaneously reduce. If a reduction maneuver is required, gentle knee extension while applying a medial force will reduce the dislocation19.
Physical examination in the acute setting may be difficult because of pain, soft-tissue swelling, and joint hemarthrosis. Palpation will help to identify the site of injury. Tenderness over the medial femoral epicondyle, the most common site of medial patellofemoral ligament failure in older patients, is known as the Bassett sign20. In skeletally immature patients, it is more likely from the patellar attachment21-23.
The patellar apprehension test is performed by applying a laterally directed force with the knee in 20° to 30° of flexion. It is positive when the quadriceps involuntarily contracts or the patient has a feeling of apprehension24,25.
The patellar glide test is performed with the knee in full extension and quadriceps relaxed. The examiner divides the patella into 4 quadrants along its width and passively translates the patella medially and laterally. A lateral patellar glide of grade 3 or 4, or >75% of the width of the patella, is indicative of medial soft-tissue insufficiency, although a side-to-side difference should be noted26,27.
Limb alignment is assessed by the quadriceps angle (Q angle), measured between lines from the anterior superior iliac spine to the center of the patella and from the center of the patella to the tibial tuberosity30-32. Factors that may increase the Q angle include genu valgum, increased femoral anteversion, external tibial torsion, a laterally positioned tibial tuberosity, and a tight lateral retinaculum30-35. Other factors may also result in a falsely low Q angle, such as patella alta, an excessive J sign (lateral subluxation of the patella as it passes the most proximal portion of the lateral trochlear ridge, typically at 20° to 30° of knee flexion), or persistent lateral subluxation of the patella36-39. Q angle measurements have been shown to have poor interobserver and intraobserver reliability30. In addition, studies have shown no difference or even lower Q angle measurements in patients with patellar instability36,40.
Patellar tracking is assessed with the examiner standing in front of the seated patient as the patient extends the knee from a flexed position. A positive J sign has been associated with vastus medialis obliquus hypoplasia, medial retinacular insufficiency, lateral retinacular contracture, patella alta, and a hypoplastic lateral femoral condyle26,33.
A standard series of radiographs including standing anteroposterior, lateral with 30° of knee flexion, tunnel, and Merchant views should be made. It is important to obtain a true lateral radiograph with symmetric overlap of the medial and lateral femoral condyles.
The lateral radiograph is the most useful in determining the presence of patella alta. Several methods have been described to measure relative patellar height, including the Insall-Salvati41, Blackburne-Peel42, Caton-Deschamps43, and Labelle-Laurin44 methods. The Blackburne-Peel ratio relies on more consistent osseous landmarks and was found to have better interobserver reliability than the Insall-Salvati method45,46. Similarly, the Caton-Deschamps Index (Fig. 1) relies on consistent osseous landmarks, can be assessed by radiographs or magnetic resonance imaging (MRI), and is independent of knee flexion between 10° and 80°47,48.
Trochlear dysplasia is evaluated on a true lateral radiograph. The trochlear floor is visible as a radiodense line. Normally, this line does not cross anterior to a line tangential to the anterior femoral cortex. Dejour et al.49 described the crossing sign when this radiodense line crosses the anterior border of the femoral condyles (Fig. 2). The crossing sign is indicative of a shallow proximal trochlea. The more distal that this radiodense line crosses the line of the anterior condyles, the more deficient the trochlea. Dejour et al.49 found the crossing sign to be present in 96% of patients with patellar instability compared with 3% of controls.
The Merchant view is made with the knee flexed 45° over the end of the table and the radiographic beam angled 30° downward50. This view is useful to assess patellar tilt, subluxation, and trochlear dysplasia. The sulcus angle is measured from the highest points on the medial and lateral femoral condyles with the apex at the deepest point of the intercondylar sulcus and is approximately 138° ± 6°50. Values of >145° are suggestive of trochlear dysplasia49. Utilizing the axial and lateral radiographs, a classification system for trochlear dysplasia has been developed (Fig. 3)49.
Three-dimensional imaging of the patellofemoral joint using computed tomography (CT) allows for more accurate measurements of the osseous anatomy. CT is also considered the gold standard to assess the lateral offset of the tibial tuberosity relative to the trochlear groove. A tibial tuberosity-trochlear groove distance of >20 mm is considered abnormal and has been used as a reference value for distal realignment procedures in patients with patellar instability49.
MRI is useful to assess the medial soft tissues supporting the patella. MRI was found to be 85% sensitive and 70% accurate in detecting injury to the medial patellofemoral ligament51. The typical findings include impaction injury to the lateral femoral condyle, osteochondral damage to the medial patellar facet, and disruption of the medial retinaculum and medial patellofemoral ligament52.
MRI may also be used to calculate the measurements otherwise made using radiographs or CT without exposing the patient to additional radiation (Fig. 4). However, recent studies have shown that MRI measurements of the tibial tuberosity-trochlear groove distance are consistently lower than CT measurements53-56. During MRI, the knee is placed in a specific coil in slight flexion and a neutral to varus position; however, the CT scan is made with the knee in full extension and a neutral to slight valgus position56. It is also difficult to define the deepest point of the trochlea in patients with trochlear dysplasia. Also, the use of a strict cutoff value (20 mm) does not account for patient size or anatomy57-60.
The tibial tuberosity-posterior cruciate ligament distance is defined as the mediolateral distance between the tibial tuberosity midpoint and the medial border of the posterior cruciate ligament (Fig. 5)61. Seitlinger et al.61 reported a tibial tuberosity-posterior cruciate ligament distance of >24 mm to be abnormal. Anley et al.55 evaluated the MRI and CT scans in the same knee of 141 patients and found a significant difference in the knee joint angle in patients with both a normal tibial tuberosity-trochlear groove distance and a normal tibial tuberosity-posterior cruciate ligament distance compared with patients with a tibial tuberosity-trochlear groove distance of >20 mm and a tibial tuberosity-posterior cruciate ligament distance of <24 mm (p < 0.05), highlighting the effect that the knee joint flexion angle can have on tibial tuberosity-trochlear groove measurement. Their data suggest that the tibial tuberosity-posterior cruciate ligament distance may be a better measure of true lateralization of the tibial tuberosity55.
Treatment strategies for patellar dislocation and instability must be patient-specific. We are proposing a treatment algorithm that is meant to help to guide treatment decisions (Figs. 6 and 7). We recognize that exceptions to this algorithm will exist, although a presentation of each such scenario is beyond the scope of this article.
Acute Primary Dislocation
Radiographs are routinely made for patients with an acute knee injury. Once the diagnosis of patellar dislocation is confirmed by history and physical examination, an MRI is acquired to evaluate for an osteochondral fragment or loose body and to identify the site and extent of injury to the medial soft tissues, particularly the medial patellofemoral ligament.
In most young patients with a first-time dislocation and no loose body within the knee, nonoperative treatment may be attempted. Our protocol includes bracing with a patellar stabilizing brace for the initial 6 to 8 weeks along with a 3-phase approach to physical therapy. Patients are initially provided with crutches and a brace, although they are allowed to weight-bear as tolerated and are advised to wean from the crutches as soon as tolerable. The initial phase (weeks 0 to 2) is focused on reducing swelling and regaining knee range of motion. Weeks 3 to 4 are aimed at regaining proprioceptive control and closed chain strengthening. This is followed by a period of functional and sport-specific training and eventual return to sport by 8 weeks.
A number of prospective, randomized studies comparing nonoperative treatment with operative treatment showed no significant difference in recurrence rates or subjective outcomes; however, they utilized older surgical techniques62-66.
Some recent studies have supported surgical treatment after acute first-time dislocation67,68. Camanho et al.67 prospectively randomized patients to surgical management (16 patients) compared with nonsurgical management (17 patients) after first-time dislocation. Femoral-sided tears were repaired using suture anchors, and patellar-sided tears were sutured arthroscopically within 4 weeks of the initial injury. At a mean follow-up of 40.4 months, the surgical treatment group had lower redislocation rates (0% compared with 50%) and improved outcome scores.
A recent systematic review of meta-analyses comparing nonoperative and operative treatment after a first-time patellar dislocation concluded that operative treatment may result in a lower redislocation rate, but there was no difference in functional outcome scores69. Erickson et al. and Smith et al. concluded that additional high-quality studies are needed with larger numbers of patients to determine the role of operative intervention in acute primary patellar dislocation69,70.
In conclusion, although some studies do support operative treatment of first-time dislocations, nonoperative management can be attempted in most young, active patients. If a recurrent dislocation occurs, operative treatment is considered.
If an osteochondral fragment or loose body is found, it is an indication for arthroscopic-assisted fixation of the fragment or removal of the loose body. Once operative treatment of the osteochondral lesion is elected, attention is directed to the medial patellofemoral ligament injury.
Several studies have shown that femoral-sided medial patellofemoral ligament tears have higher rates of recurrent instability and poor outcome scores. Sillanpää et al.71 showed that, at a mean follow-up of 7 years, 35 patients with femoral-sided medial patellofemoral ligament tears had a redislocation rate of 32% and a subjective instability rate of 52%, 11 patients with midsubstance medial patellofemoral ligament tears had a redislocation rate of 9% and a subjective instability rate of 9%, and 7 patients with patellar-sided medial patellofemoral ligament tears had a redislocation rate of 0% and a subjective instability rate of 17%. Another study divided the medial patellofemoral ligament into 2 anatomic regions based on overlap with the vastus medialis obliquus. Their results suggest that medial patellofemoral ligament tears within the overlap region at the patellar side have more potential to heal on the basis of the location within the extracapsular layer and adherent attachment with the vastus medialis obliquus72. In patients with a femoral-sided complete medial patellofemoral ligament tear undergoing surgical treatment of an osteochondral lesion, we recommend performing medial patellofemoral ligament reconstruction because of the high potential for recurrence of patellar instability.
Imbrication of the medial retinaculum or “reefing” may still have a role in appropriately selected patients with patellar-sided medial patellofemoral ligament disruption, especially in patients with open physes. Shelbourne et al.73 reported on 38 patients who underwent medial retinacular imbrication after acute patellar dislocation; at a mean follow-up of 31.7 months, 87% of the patients had returned to their preinjury level of activity, including sports. It is important to consider that medial imbrication is a nonanatomic procedure and may result in excessive medialization of the patella74. If patients were to return with recurrent instability, medial patellofemoral ligament reconstruction remains a salvage procedure following this technique.
Recurrent Patellar Instability
Patients who present with recurrent patellar instability undergo radiography and MRI to evaluate underlying bone morphology and associated soft-tissue injuries. Patients are then grouped according to the presence or absence of anatomic abnormalities (Fig. 7). Other anatomic abnormalities may also contribute to recurrent instability (Table I)49. Patients with no underlying osseous abnormality who experience a traumatic recurrent dislocation will typically undergo medial patellofemoral ligament reconstruction.
Trochlear dysplasia can be described by a number of classification systems. The original classification was developed by Henri Dejour49 and was popularized by his son David Dejour75 (Fig. 2). Although trochlear dysplasia is very common in patients with recurrent patellar instability (96% in the series by Dejour and Le Coultre75), substantial dysplasia requiring direct reconstruction of the trochlea is exceedingly rare, even in salvage situations, because of the risk of osteoarthritis.
In skeletally mature patients with recurrent patellar instability and trochlear dysplasia, the initial approach is to address other anatomic factors that may accommodate for the dysplastic trochlea, such as by medial patellofemoral ligament reconstruction with or without tibial tuberosity osteotomy76. In salvage situations, direct reconstruction of the trochlea with a deepening trochleoplasty or elevation of the anterior portion of the lateral femoral condyle (Albee77 trochlear osteotomy) may be an option. Numerous techniques are described, with variable results77-84.
Sulcus-deepening trochleoplasty may be used as a salvage procedure in patients with severe high-grade trochlear dysplasia (Dejour type B or D) with recurrent patellar instability and the absence of osteoarthritis82. Most techniques involve the removal of cancellous bone and the compression of the overlying cortical bone and articular cartilage into the defect to deepen the sulcus. Patients with Dejour type-C dysplasia may be more appropriate candidates for lateral facet elevating trochlear osteotomy82. However, this technique has fallen out of use because of the alteration in patellofemoral joint mechanics and increased incidence of patellofemoral pain and arthrosis85. One biomechanical study showed that as little as 3 mm of elevation of the lateral condyle will increase patellofemoral contact pressures85.
Von Knoch et al.80 reported on 45 knees in 38 patients who underwent trochleoplasty and medial reefing with or without medial patellofemoral ligament reconstruction. At a mean follow-up of 8.3 years, there were no redislocations, although 1 patient had recurrent subluxation. Importantly, 23% of patients had evidence of degenerative change in the patellofemoral compartment on radiographs, and 43% reported worsening of preoperative patellofemoral pain80.
Zaki and Rae84 reported on 27 knees in 25 patients who underwent trochleoplasty for patellar instability and trochlear dysplasia. At a mean follow-up of 4.5 years, there were no recurrences; however, 33% of knees were reported as having ongoing pain, swelling, and crepitus84.
Trochleoplasty in combination with medial soft-tissue stabilization has been shown to prevent recurrent patellar instability; however, persistent anterior knee pain is common, and damage to the articular cartilage is a serious concern76. This technique is best reserved for patients with severe dysplasia who have previously undergone failed attempts to provide patellofemoral stability with other techniques in the absence of osteoarthritic changes76.
Isolated Medial Patellofemoral Ligament Reconstruction
One of the earliest reports of isolated medial patellofemoral ligament reconstruction for patellar instability with trochlear dysplasia came in 200686. Steiner et al.86 reported on 34 patients; at a mean follow-up of 5.5 years, there were no recurrent dislocations and a significant improvement in outcome scores. They also found no difference between the severity of dysplasia and postoperative outcome scores86.
Medial patellofemoral ligament reconstruction is not without complications. Patellar fracture, adductor tubercle fracture, graft loosening, nonunion of bone-tendon grafts (graft failure), infection, arthrofibrosis, and loss of motion have all been reported87,88. Also, overtightening or malpositioning of the tunnels may cause medial patellofemoral overload leading to patellofemoral pain and arthrosis or medial subluxation87,88. Undertightening may lead to recurrent lateral instability87,88.
In conclusion, in patients with recurrent patellar instability and trochlear dysplasia, we suggest performing isolated medial patellofemoral ligament reconstruction initially. In patients with failed isolated medial patellofemoral ligament reconstruction, trochleoplasty may be used as a salvage procedure in the absence of patellofemoral osteoarthritic changes.
Lateralized Tibial Tuberosity
Patients with an elevated tibial tuberosity-trochlear groove distance of >20 mm or a tibial tuberosity-posterior cruciate ligament distance of >24 mm are considered for tibial tuberosity osteotomy, typically in combination with medial patellofemoral ligament reconstruction. Various techniques for tibial tuberosity osteotomy have evolved over the years. The Roux-Elmslie-Trillat procedure involves open lateral retinacular release, medial displacement of the tibial tuberosity hinged distally with periosteum, and medial capsular reefing89. This is indicated in patients with recurrent instability, an excessive tibial tuberosity-trochlear groove distance, and Outerbridge90 grade-≤2 chondromalacia of the medial patellofemoral joint at arthroscopy91. Fulkerson introduced the anteromedialization technique, which is indicated in patients with grade-3 or 4 chondromalacia of the lateral patellofemoral joint92,93. This technique utilizes a more oblique cut and transfers the tuberosity slightly anteriorly and medially91-93. Anteromedialization can predictably improve patellofemoral tracking, can unload the lateral and distal articular surface, and can decrease overall patellofemoral contract stress by shifting the contact area proximally and medially92-94. In patients with previous patellar dislocation, these realignment procedures are combined with medial patellofemoral ligament reconstruction to address insufficient medial soft-tissue restraints91.
Buck and Fulkerson94 reported 86% good to excellent results at a mean follow-up of 8.2 years in 36 patients (42 knees) who had undergone anteromedialization of the tibial tuberosity. Poor outcomes were associated with grade-3 or 4 chondromalacia in the medial or central part of the trochlea and in patients with Workers’ Compensation94. Pritsch et al.95 reported 72.5% good or excellent results at a mean follow-up of 6.2 years in 55 patients (69 knees). Poor prognostic factors included preoperative pain and instability compared with isolated instability, female sex, and moderate to severe patellar chondral damage95. Pidoriano et al.96 showed that the location of the patellar chondral lesion correlates with outcome following anteromedialization. Patients with chondral lesions of the distal part of the patella (10 patients) and of the lateral facet (13 patients) reported 87% good to excellent results, whereas patients with medial facet chondromalacia (9 patients) reported 55% good to excellent results and those with proximal or diffuse chondromalacia (5 patients) reported 20% good to excellent results. All 7 patients with central trochlear lesions had poor results96.
Patients with proximal or medial patellofemoral joint chondromalacia have poor outcomes with anteromedialization97-99. Additionally, over-medialization of the tibial tuberosity has been shown to increase patellofemoral contact stress and may lead to osteoarthritis99. Postoperative fractures of the proximal part of the tibia and tibial tuberosity have been reported more often after anteromedialization compared with the less invasive medialization tibial tuberosity osteotomy; anteromedialization also requires a prolonged period of protected weight-bearing88. Arthrofibrosis, wound complications, painful implants, compartment syndrome, nonunion, malunion, and saphenous vein or nerve injury are all potential complications with anteromedialization 88.
In conclusion, patients with an elevated tibial tuberosity-trochlear groove distance of >20 mm or a tibial tuberosity-posterior cruciate ligament distance of >24 mm and recurrent patellar instability may benefit from tibial tuberosity osteotomy in combination with medial patellofemoral ligament reconstruction to improve patellar tracking. Diagnostic arthroscopy must be performed to determine the presence and grade of chondromalacia prior to any tibial tuberosity osteotomy. In patients with grade-≥2 chondromalacia of the medial patellofemoral joint, tibial tuberosity osteotomy should be avoided.
Patellar height is evaluated using the Caton-Deschamps Index, as this ratio uses reliable osseous landmarks and is independent of the tibial tuberosity position48. One study has suggested that increased patellar tendon length (>52 mm) is the contributing factor to patella alta and instability because of increased coronal plane motion47.
When patella alta is identified (Caton-Deschamps Index of >1.2), patients are considered for distalization tibial tuberosity osteotomy. Similar to medialization and anteromedialization tibial tuberosity osteotomies, patients will undergo diagnostic arthroscopy to evaluate for chondral lesions of the patellofemoral joint. Distalization will shift contact pressure to the distal surface of the patella, and it is important to assess for chondromalacia in this area specifically100. Isolated distalization procedures of the tibial tuberosity will cause the patella to engage the trochlea in earlier degrees of flexion, increasing osseous restraint in the absence of severe trochlear dysplasia101.
Mayer et al.101 reported on 27 knees in 22 patients with patella alta and recurrent patellar instability who underwent tibial tuberosity distalization combined with patellar tendon tenodesis. All patients had vastus medialis obliquus advancement, and 22 of the knees also underwent medialization of the tibial tuberosity for an elevated tibial tuberosity-trochlear groove distance of >20 mm. At a mean follow-up of 9.6 years, there were no incidents of patellar redislocation, although 33.3% of knees had a positive apprehension test. Overall, 92.5% of patients were satisfied or very satisfied with the operation. Mayer et al. recommended medial patellofemoral ligament reconstruction over vastus medialis obliquus advancement to stabilize the medial soft tissues101.
Caton and Dejour48 retrospectively reported on 61 knees in 50 patients who had undergone medialization or distalization tibial tuberosity osteotomy. They reported perfect postoperative stability in 77% of patients, although it is unclear how this was defined. In the series by Pritsch et al.95, 90% of patients had distalization performed as well as medialization. Palmer et al.102 reported on 59 knees with patellar instability that underwent medialization and distalization. At a mean follow-up of 5.6 years, 79% of patients had good or excellent results, and the authors noted 2 cases of recurrent dislocation102.
In conclusion, distalization of the tibial tuberosity can be used in combination with medial patellofemoral ligament reconstruction in patients with recurrent patellar instability and patella alta (Caton-Deschamps Index of >1.2). Diagnostic arthroscopy is performed to assess for chondromalacia at the distal part of the patella prior to distalization. Even without evidence of chondromalacia, distalization may increase contact pressure, and patients should be counseled regarding the risk of patellofemoral arthritis. Distalization is performed to achieve a Caton-Deschamps Index of <1.0.
External patellar tilt can be assessed on MRI or CT as the angle formed by a line through the transverse axis of the patella and a line along the posterior femoral condyles49. Dejour et al.49 found an external patellar tilt angle of >20° in 83% of patients with patellar instability and in 3% of controls. Patellar tilt may also be assessed radiographically by the lateral patellofemoral angle of Laurin et al.103. Excessive patellar tilt is a result of surrounding soft-tissue or osseous abnormalities. Dynamic patellar tilt may result from vastus medialis obliquus dysplasia104. A fixed patellar tilt can be due to lateral retinacular tightness105. There is also a high statistical correlation between the severity of trochlear dysplasia and the degree of patellar tilt106.
Historically, lateral retinacular release was commonly performed. However, given advancements in other surgical techniques, isolated lateral release has no role in acute or recurrent patellar instability107. Lateral release has also been performed in combination with realignment and medial soft-tissue stabilizing procedures, although with mixed results. Complications of lateral release include medial patellar instability, hemarthrosis, recurrent effusions, and adhesions107.
In conclusion, lateral release may be performed in combination with medial soft-tissue stabilizing procedures in the setting of an excessively tight lateral retinaculum, although there is a substantial risk of iatrogenic medial patellar instability. Currently, this procedure is rarely used in our practice.
Although there are a number of studies regarding patellar instability, the studies are mostly of low quality and there is not consistency in reporting of preoperative factors with postoperative outcomes108. Reporting outcomes based specifically on patellar instability, such as the Banff Patella Instability Instrument109 and the Norwich Patellar Instability Score110, may improve the quality of evidence to better assist in clinical decision-making in the future. The treatment algorithm presented in the current article is based on currently available evidence, and, as with any complex problem, treatment should be individualized to address the needs of each patient.
Investigation performed at the Division of Sports Medicine, Department of Orthopaedic Surgery, Allegheny General Hospital, Pittsburgh, Pennsylvania
Disclosure: No external funds were received in support of this study. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work.
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