Review of Common Clinical Conditions of the Proximal Tibiofibular Joint
Mr. Curatolo is a medical student at The Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York. Dr. Mutty is Clinical Assistant Professor, Department of Orthopaedics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York. Dr. Marzo is Clinical Professor, Department of Orthopaedics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York. Dr. Bach is a resident, Department of Surgery, University of South Florida Morsani College of Medicine, Tampa, Florida.
Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.
Address correspondence to: John Marzo, MD, The Jacobs School of Medicine and Biomedical Sciences, 955 Main St, Buffalo New York, 14203 (tel, 716-829-2982; fax, 716-829-3945; email firstname.lastname@example.org).
Am J Orthop. 2018;47(12). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
Current literature is limited with respect to the proximal tibiofibular joint (PTFJ) and clinical conditions relating to the PTFJ. Diagnosis and treatment of conditions that affect the PTFJ are not well described and are a topic of debate among many physicians. This manuscript aims to review and summarize the most recent literature that relates to traumatic dislocations, fractures, chronic instability, and osteoarthritis, with a focus on both diagnostic and treatment strategies of these conditions. We also review PTFJ anatomy, biomechanics, and the clinical presentation of some common PTFJ conditions.
- Problems of the proximal tibiofibular joint (PFTJ) should be considered in the differential diagnosis when a patient presents with complaints in the lateral aspect of the knee.
- The primary function of the PTFJ is to transmit and absorb axial loads from weight bearing on the extremity, and to dissipate torsional loads applied to the leg and ankle.
- The most common instability pattern is anterolateral fibular displacement.
- Most proximal tibiofibular joint instabilities can be treated with closed reduction and conservative care, but some require internal fixation or soft-tissue reconstruction.
- Arthritic conditions of the PTFJ are treated similar to those of any diarthrodial joint, with additional option of surgical arthrodesis or resection arthroplasty.
Clinical conditions of the proximal tibiofibular joint (PTFJ) are an uncommon source of lateral knee complaints and are often overlooked in the differential diagnosis as a source of the knee complaint. The most common conditions of the PTFJ include traumatic dislocations, fractures, chronic instability, and osteoarthritis. This article reviews the most common diseases affecting this joint and discusses both diagnostic and treatment strategies in an attempt to raise awareness of this joint as a source of lateral knee complaints.
The PTFJ is an arthrodial synovial joint between the posterolateral surface of the tibia and the proximal fibular head.1 Surrounding the synovial membrane of the articulation is a fibrous joint capsule with distinct anterior and posterior tibiofibular ligaments.2,3 The anterior tibiofibular ligament has been described as 1 or 2 bands whereas the posterior ligament consists of 1 band.3 The anterior ligament attaches anteroinferiorly to the fibular styloid and posteriorly to Gerdy’s tubercle on the tibia. It runs linearly from posterior to anterior, and the fibular footprint is immediately anterior to the insertion of the biceps femoris. The posterior ligament is located inferior to the lateral joint space, and the fibular footprint is posterior to the insertion of the biceps femoris.3 Anatomy of the PTFJ is shown schematically in Figure 1.
Both the lateral collateral ligament (LCL) and the tibiofibular interosseous membrane add stability to the PTFJ. The LCL travels from the lateral femoral epicondyle to the lateral side of fibula head, anterior to the fibular styloid. The interosseous membrane extends obliquely between the borders of the tibia and fibula. Additionally, the short head of the biceps femoris, fibular collateral ligament, fabellofibular ligament, popliteofibular ligament, and popliteus muscle all attach to the PTFJ and provide additional stability to the joint.
It is important to note that the common peroneal nerve passes posteriorly over the fibula neck, can be involved in the clinical presentation, and is a potential source of concern with any injury to or surgery on the joint.4
Many studies have demonstrated that a communication with the tibiofemoral joint exists through the subpopliteal recess, but the rate of communication has varied widely.5-8 Most recently, Bozkurt and colleagues5 found the rate of communication between the PTFJ and lateral femorotibial space to be 57.9%. When distinct communication exists, the PTFJ must be considered as a fourth compartment of the knee and is subject to any process that affects the knee joint proper.
Ogden1 described 2 types of PTFJs, horizontal and oblique, with the latter being considered less stable because of less rotational mobility. The horizontal configuration is defined as <20° of inclination of joint surface in relation to the horizontal plane, and the oblique variation is defined as >20° of inclination of the joint surface in relation to the horizontal plane.1
Biomechanics and Function
The primary function of the PTFJ is to dissipate torsional loads applied to the ankle, attenuate lateral tibial bending moments, and transmit axial loads from weight bearing on the extremity.1 The degree of knee flexion, ankle dorsiflexion, and tibial rotation all play an important role in PTFJ biomechanics. In knee flexion, the proximal fibula moves anteriorly because of the relative laxity of the LCL and biceps femoris tendons. In knee extension, the LCL and biceps femoris tighten, pulling the proximal fibula posteriorly.1 Because the LCL and biceps tendon are both relaxed and less supportive during knee flexion, the PTFJ is more prone to injury with a flexed knee. The ankle plays an important role in the biomechanics of the PTFJ because it contains the distal syndesmosis, where both the tibia and fibula are firmly attached distally. During ankle dorsiflexion, the fibula must externally rotate to accommodate a wider anterior talus.1 In regard to tibia rotation, Scott and colleagues9 demonstrated the relationship between tibial rotation and fibular translation. With internal tibial rotation, the fibular head translated posteriorly and with external tibial rotation, the fibula translated anteriorly. The greatest translational motion was seen during loading of the knee into varus and during external tibial rotation at all flexion angles.
Ogden10 classified instability of the PTFJ into 4 main groups: anterolateral dislocation, posteromedial dislocation, superior dislocation, and atraumatic subluxation. Injury to the PTFJ usually occurs in younger, athletic patients during sports that require violent twisting motions such as soccer, basketball, dance, skiing, horseback riding, parachute jumping, jet skiing, and judo. Patients with generalized ligamentous laxity have been described as at increased risk for joint instability.10,11
The most common injury to the PTFJ is an anterolateral dislocation and involves injury to both the anterior and posterior capsular ligaments, and occasionally the LCL.10 Anterolateral dislocation is usually the result of a fall on a hyperflexed knee with the foot inverted and plantarflexed.11 While most anterolateral dislocations are the result of indirect sports trauma, several have been associated with other types of skeletal injuries such as fracture-dislocation of the hip, crush injury of the proximal and distal ends of the tibia, fracture-dislocation of the ankle, proximal tibial fracture, and fracture-dislocation of the distal femoral epiphysis.10 Ogden10 described the mechanism as follows: (1) sudden inversion and plantar flexion of the foot causing tension in the peroneal muscle group, extensor digitorum longus, and extensor halluces longus, which applies a forward dislocating force to the proximal end of the fibula; (2) simultaneous flexion of the knee, relaxing the biceps tendon and LCL; and (3) twisting of the body over the knee, transmitting energy along the femur to the tibia, exerting a relative external rotatory torque of the tibia on the foot, which is already fixed in inversion. Steps (2) and (3) spring the proximal end of the fibula laterally while the contracting muscles of (1) pull the fibula anteriorly.
Posteromedial dislocation is the second most common type of acute PTFJ dislocation. Posteromedial dislocations usually involve direct trauma and are associated with peroneal nerve injuries.1,2,10 The mechanism of dislocation results in tearing of the anterior and posterior PTFJ capsular ligaments, followed by injury to the LCL and other surrounding ligaments. This allows the biceps femoris to draw the unsupported proximal part of the fibula posteromedially along the posterolateral tibial metaphysis.7
Superior dislocations are the least frequent form of acute PTFJ dislocations and are associated with high-energy ankle injuries.2,10,12 Superior dislocation results in injury to the interosseous membrane between the tibia and fibula and is frequently associated with tibial shaft fracture.10,11 Atraumatic, acquired superior dislocation of the PTFJ has also been associated with congenital dislocation of the knee.10,11
Subluxation of the PTFJ classically involves excessive and symptomatic anterior-posterior motion without actual dislocation of the joint.11 Subluxations of the PTFJ typically occur without any known trauma or injury and are most frequently associated with benign hyperlaxity syndrome, Ehlers-Danlos syndrome, or muscular dystrophy.4,10
Semonian and colleagues13 suggest that subluxation of the PTFJ is not given enough recognition in the literature and that instability should not be considered a rare condition. They hypothesize that many patients have joints that do not tolerate increases in fibula rotation secondary to subclinical trauma, repetitive overuse, or biomechanical variation of the joint. Semonian and associates13 state that the condition begins with the anterior capsule and anterior tibiofibular ligament attenuation as a result of excessive fibular rotation. Once stretched, the functional pull of the biceps femoris and soleus maintain the fibula in a relatively posterior and externally rotated position. Furthermore, Ogden10 found that 70% of the dislocations and subluxations he studied were of the oblique variant compared with that of the horizontal variant. Many authors suggest that the oblique variant is more at risk for injury because of its decreased joint surface area causing decreased rotational mobility.1,2,10
Early recognition is extremely important in dislocations and subluxations of the PTFJ as undiagnosed acute trauma can turn into chronic subluxation, and chronic subluxation may lead to dislocation.13 Additionally, chronic subluxation or dislocation are thought result in osteoarthritis of the PTFJ.14
The literature on osteoarthritis of the PTFJ is limited. Eichenblat and Nathan7 studied the PTFJ in cadavers and dry bones and found that 28% had evidence of osteoarthritis. Clinically, however, osteoarthritis of the PTFJ is a rare primary diagnosis, suggesting that involvement of the PTFJ is either asymptomatic or that symptoms are associated with osteoarthritis of the knee joint. Boya and colleagues15 and Eichenblat and Nathan7 both found a high correlation between the presence of osteoarthritis of the PTFJ and osteoarthritis of the tibiofemoral joint in cadavers. The authors suggest this correlation may be related to the presence of anatomical communication between the 2 joints. Theoretically, inflammatory mediators flow freely between the joint spaces and contribute to arthritis in both joints. The possibility of degenerative arthritis of the PTFJ accompanying degenerative arthritis of the knee warrants evaluation, especially in patients considering total knee arthroplasty. Unrecognized arthritis of the PTFJ might influence outcome scores and be an unsolved source of lateral knee pain post-knee replacement.16
Patients with acute PTFJ dislocation present with pain, tenderness, swelling, and asymmetry of the lateral side of the knee, while the knee joint is not swollen and range of knee motion is not limited.17 A bony prominence might be felt, and the biceps femoris tendon can often appear to be tense.13 Active or passive ankle movements often exacerbate the lateral knee pain.11 It is also important to examine the peroneal nerve, as transient peroneal palsy has been described in all types of PTFJ dislocations but most often with posteromedial dislocations. Sensory disturbance in the peroneal nerve distribution is more common than motor loss, but foot drop is also a potential presenting sign.11 On examination, palpation of the fibular head illustrates tenderness and aggravates the pain.
Subluxation of the PTFJ can be difficult to recognize because the history, signs, and symptoms of lateral knee pain can be subtle and sometimes misleading. In addition, current literature provides little information on specific tests, measurements, signs, or subjective information regarding subluxation. Patients rarely reveal a history of trauma or mechanism of injury. Subluxations are often associated with patients participating in repetitive sports requiring running, jumping, or twisting movements, and can be present bilateral. Instability has also been described in patients with osteomyelitis, rheumatoid arthritis, septic arthritis, pigmented villonodular synovitis, below-knee amputations, osteochondroma, and in runners who recently increased mileage (especially during the first 2-3 miles and during downhill running).11,13 Patients normally do not have difficulty with activities of daily living, but symptoms may arise when making movements with a sudden change of direction.11
These patients usually complain of instability of the knee and pain along the lateral aspect of the knee. Pain radiating proximally into the region of the iliotibial band and medially into the patellofemoral joint can be seen.13 Patients may also report clicking, popping, or catching of the lateral knee; while others will report a sense of giving way of the knee joint.11,13 Progressive peroneal nerve symptoms are usually seen in older patients; however, they are more common with acute PTFJ dislocations as discussed.13
A clinical method for examining a PTFJ with possible subluxation or chronic instability has been described by Sijbrandij.18 With the patient in the supine position, the knee is flexed to 90° to relax the LCL and biceps femoris tendon. The fibular head is then held between the thumb and index finger, and moved anteriorly and laterally. Dislocation or subluxation will be felt and visualized as the fibular head translates, and should be compared with the uninjured PTFJ. On release, the fibular head will return to its normal position, often with a click. Asking the patient if this subluxation/reduction maneuver reproduces the symptoms or causes apprehension or pain may also be helpful.18 Another method for examination is eliciting the Radulescu sign.11,13 While the patient lies prone, the examiner stabilizes the thigh with 1 hand while the knee is flexed to 90°. The examiner then applies an internal rotation force on the lower leg. Observing an abnormal excursion of the fibular head in an anterior and lateral direction represents a positive test.11,13
Clinical evaluation for osteoarthritis in the PTFJ is not well described in the literature. A single report describes applying manual pressure over the fibular head during active ankle motion.16 A test known as the grinding test is used as a sign to detect the involvement of the PTFJ as a component of osteoarthritis of the knee. A positive test will elicit pain and/or tenderness of the joint.16
Plain radiographs in the anteroposterior (AP) and true lateral views are useful as first-line investigations in suspected PTFJ dislocation. Comparable AP and lateral radiographs of each knee are highly recommended to detect findings that suggest dislocation.2 Abnormal findings include increased interosseous space, medial or lateral displacement of the fibula on the anteroposterior view, and anterior or posterior displacement of the fibula head on lateral view as shown in Figure 2.19,20
Resnick and colleagues2 proposed the use of the linear sloping radiodensity that defines the posteromedial corner of the lateral tibial condyle as an indicator of anterolateral or posteromedial PTFJ dislocation. However, this application is limited because of the PTFJ’s highly variable morphology.8 In a recent study conducted by Hey and colleagues,21 5968 (2984 patients) knee radiographs were retrospectively collected and subjected to radiographical measurements and statistical analysis. The tibiofibular overlap method had a specificity of 94.1% and 84.5% when diagnosing PTFJ dislocations on the AP and lateral views, respectively.21
If a diagnosis of PTFJ is suspected but not clearly established based on radiography, computed tomography with comparison views of the contralateral knee are recommended to confirm the diagnosis.17,22 This becomes more critical in cases of suspected subluxation/chronic PTFJ instability. Additionally, magnetic resonance imaging (MRI) can be used to assess chronic PTFJ instability. Recently, Burke and colleagues23 performed a 10-year retrospective case series that included 7 patients with chronic PTFJ instability and included MRI as part of their evaluation. The MRI abnormalities in these patients included periarticular soft tissue edema, including in the proximal soleus muscle (n = 5), periarticular ganglion or ganglia (n = 4), tibiofibular ligament edema (n = 4), subchondral marrow edema (n = 3), posterior tibiofibular ligament thickening (n = 2), subcortical cyst at a ligament insertion (n = 2), partial-thickness tear of the anterior tibiofibular ligament (n = 1), and tibiofibular joint effusion (n = 1).
Routine knee radiographs can show PTFJ joint space narrowing, sclerosis, marginal osteophytes, and local osteopenia as conventional components of osteoarthritis of any joint. Serial radiographs have also been described as effective in evaluating progressive degenerative changes of the PTFJ.14 An MRI will show osteophyte formation, subchondral cysts, subchondral sclerosis, joint effusion, joint space narrowing, and is highly sensitive for detecting degenerative changes in cartilage, as well as identifying other possible pathologies such as synovial cysts or pigmented villonodular synovitis. Chronic PTFJ instability appears to predispose to tibiofibular osteoarthritis as reported by Burke and colleagues,23 who found a particularly high incidence (42.9%) of osteoarthritis in patients with chronic PTFJ instability. Additionally, Veth and colleagues14 found degenerative changes in 8 of 19 patients presenting with PTFJ dislocations.
Prompt recognition and treatment of any acute PTFJ dislocation are necessary to avoid long-term instability and other possible sequelae.11 Treatment consists of reduction followed by restriction of weight-bearing.11 Traditionally, the knee is immobilized with a cast in extension for 3 to 4 weeks followed by knee mobilization and progressive range of motion exercises,24 but there is some controversy regarding complete immobilization.11,25,26
Initially, closed reduction is advised as the treatment for acute PTFJ dislocation.11,19,24 It involves placing the knee in 80°to 110° of flexion to relax the biceps femoris and LCL, then applying an appropriate force to the fibular head in a direction opposite the displacement.11,24 An audible pop is often heard as the fibula reduces back into normal alignment. Stability of the reduction and stability of the knee should be determined with respect to both posterolateral structures and the LCL after reduction.11 Anterolateral dislocations are usually easier to reduce, as a posteromedial or superior dislocation can result in the fibular head being perched on the lateral tibial ridge, and held by the LCL.11
Calabró and colleagues27 described a new, simple, and safe alternative technique of closed reduction of an anterior dislocation if the classical method fails. This technique relies on ligamentotaxis and a dynamic counteraction between muscles and ligaments to reduce the joint. The patient flexes the knee >90° while the physician applies a counterforce to the heel with the palm. Simultaneously, gentle direct pressure should be applied to the fibular head to move it toward the lateral tibial ridge. With a relaxed LCL, the biceps femoris tendon will actively reduce the proximal fibular head back into its correct anatomic orientation.27
When a closed reduction in an awake patient has failed, a reduction under sedation or anesthesia should be performed. If that fails, an open reduction should be performed. Following an open reduction, the joint is stabilized with Kirschner wires, bioabsorbable pins, or cortical screws.24-26,28 The torn capsule and any injured ligaments should also be primarily repaired. After approximately 6 weeks, the stabilization hardware may be removed.24,25
Acute posteromedial dislocations are treated similarly to anterolateral dislocations; however, open reduction and repair of the capsule and ligaments are more frequently required.10 Superior dislocations are also more frequently reduced by open methods, sometimes dictated by open treatment of associated tibia or ankle fracture.10 Damage to any structure of the posterolateral knee as a result of acute PTFJ injury should be repaired, as this has been associated with better outcomes.14
PTFJ dislocation and tibia fracture can occur together, and in a retrospective study conducted by Herzog and colleagues29 the authors recorded the incidence of PTFJ dislocation as 1.5% of operative tibial shaft fractures and 1.9% of operative tibial plateau fractures. Haupt and colleagues30 also conducted a retrospective study in which the authors recorded the incidence of PTFJ dislocations in 1.06% of all tibial shaft fractures in their series. In both studies combined, all except 1 PTFJ dislocation had been caused by high-energy trauma.29,30 In the case of PTFJ dislocation with tibial shaft fracture, intramedullary nailing of the tibial shaft fracture followed by open reduction of the PTFJ with 1 or 2 positioning screws just below the PTFJ has yielded satisfactory results.30 The positioning screw should be removed 6 weeks post-operation to prevent PTFJ arthrodesis and patients should be supported in full weight-bearing.30 An illustrative case report from our institution is shown in Figure 3.
Chronic instability is commonly the result of untreated or misdiagnosed subluxation of the PTFJ. Ogden10 reported that 57% of patients with acute proximal tibiofibular dislocations required surgery for ongoing symptoms after treatment failure with closed reduction and 3 weeks of immobilization. The first step in the management of chronic instability of the PTFJ is usually a nonoperative approach. Immobilization, activity level modification, utilization of a supportive strap placed 1 centimeter below the fibular head for pain relief, and participation in a strength-training program of the lower leg are initial treatment recommendations.10,11,13 Many patients with chronic PTFJ instability do not respond to conservative treatment and may pursue surgical intervention. Surgical treatment options include permanent arthrodesis, resection of the fibular head, soft tissue reconstruction, and temporary fixation.10,13,26,31 Given the rare nature of the injury and lack of data on varying treatments, there is no clear consensus on the optimal surgical procedure.
Arthrodesis and fibular head resection are 2 traditional methods of surgically addressing the PTFJ, but both have limitations that need to be recognized. Arthrodesis involves clearing the PTFJ of all articular cartilage, bone grafting, and then reducing the joint using screw fixation.11 Rigid fixation prevents rotation of the fibula which puts additional stress on the ankle, frequently causing pain and instability of the ankle joint.10,11 The other traditional surgical option, fibular head resection, involves excision of the head and neck of the fibula while preserving the fibular styloid and LCL.4 Fibular head resection is indicated when peroneal nerve symptoms or palsy occur in PTFJ injuries.4,10 Unfortunately, resection may disrupt the posterolateral corner structures of the knee and result in pain and instability.3,13 As a general rule, it is advisable to avoid arthrodesis and fibular head resection in children and athletes because of the length of time during which complications can develop.11
Van den Bekerom and colleagues26 suggest that their technique of temporary fixation of the PTFJ using a cancellous screw yields satisfactory outcomes in treating chronic PTFJ instability. The method entails having the ankle dorsiflexed and the head of the fibula slightly externally rotated and reduced into the most stable position. A hole is drilled in the anteromedial direction from posterior fibula head into the tibia. A non-tapped cortical screw is used to fix the fibula head in the reduced position.26 The screw is removed after 3 to 6 months. Seven of 8 patients treated with this technique by Van den Bekerom and colleagues26 have had alleviation of symptoms, although the screws broke in 2 cases before their planned removal.
Soft tissue reconstruction of the PTFJ has been an evolving area of treatment. Several techniques using a variety of tissue grafts and fixation methods have been described. Giachino32 proposed a reconstruction in which the fibular head is stabilized with a strip of ipsilateral biceps femoris tendon still attached distally to the fibular head and deep fascia of the leg. Drill holes are made in the tibia, and the tissue is secured anteriorly to the fascia with a suture. Shapiro and colleagues33 performed a stabilization using a strip of the iliotibial band still connected to its insertion on Gerdy’s tubercle. The graft was tunneled through a tibial drill hole from anterior to posterior and through the fibular head from posterior to anterior before suturing back onto itself. Another technique described by Mena and colleagues34 uses a split biceps tendon autograft, harnessing the strong attachments of the tendon to the fibular head to stabilize the reduced PTFJ.
More recently, Miller35 employed elements of the techniques described by Gianchino,32 Shapiro and colleagues,33 and Mena and colleagues34 to develop a method involving the biceps femoris tendon and iliotibial band in a soft tissue reconstruction. The technique involves harvesting the biceps femoris tendon while preserving the distal insertion and harvesting the iliotibial band while leaving the distal insertion at the Gerdy’s tubercle intact.35 The biceps tendon is passed from posterior to anterior through a tibial bone tunnel, and the iliotibial band graft is passed through the same tunnel but in the anterior to posterior direction. A bioabsorbable interference screw is placed into the tibial tunnel from anterior to posterior. The remaining biceps tendon graft is sewn into the soft tissue of the anterior tibia. The tail of the iliotibial band graft is passed through the fibular bone tunnel in the posterior to anterior direction and looped around the fibular head and under the LCL before being sewn back onto itself.35 Kobbe and colleagues36 described a surgical technique using the ipsilateral semitendinosis tendon while Maffulli and colleagues37 and Morrison and colleagues38 presented techniques using the ipsilateral gracilis tendon. These techniques do not jeopardize lateral knee or fibular head stability by avoiding the use of the biceps femoris and iliotibial band, as well as local knee stabilizers. Warner and colleagues31 proposed a similar technique to the aforementioned using a semitendinosus tendon; however, they do not reconstruct the anterior ligamentous structures, as seen in Figures 4A and 4B.39 The authors have concerns that a 2-limb reconstruction as described by Kobbe and colleagues36 and Morrison and colleagues38 may be prone to overconstraint or other errors in tensioning because it does not allow for differential tension to be applied to each limb.31 According to Warner and colleagues,31 the anterior structures of their patients with chronic PTFJ instability have appeared normal, and isolated posterior ligamentous reconstruction has been adequate for the restoration of stability. Camarda and colleagues28 proposed a technique very similar to that of Warner and colleagues;31 however, the tibial tunnel is reamed from posterolateral to the anteromedial aspect of the tibia, exploiting the skin incision previously used for tendon harvest.
The management options for secondary arthritis due to chronic PTFJ instability have rarely been discussed in the literature. Arthrodesis or fibular head resection are options for the treatment of arthritis, and the above discussion applies here as well. Yaniv and colleagues40 describe a technical procedure for addressing both instability and secondary joint arthritis. The authors performed a ligament reconstruction of the PTFJ using the anterior part of the biceps femoris combined with interpositional joint arthroplasty using a vascularized fascia lata strip. Two weeks post-operation, the patient was walking with full weight-bearing and 6 weeks post-operation the first sports activities were allowed.40
Conditions affecting the PTFJ, their diagnosis, and treatment are infrequent topics of discussion in the literature. While PTFJ injury, instability, and other disease states are admittedly rare, clinicians need to include them in the differential diagnosis of patients presenting with lateral knee complaints. Diagnostic imaging is a critical component in early identification of PTFJ conditions to prevent long-term complications. Most injuries are treated first with conservative methods, reserving surgery as an option when first-line measures are unsuccessful. Advancements in surgical options for dislocation and subluxation/chronic instability of the joint have been made, but further research on their effectiveness and long-term outcomes is needed before a gold-standard treatment can be determined.