Authors

1. Cesar Cornejo Ochoa OMS I – Western University of Health Sciences – College of Osteopathic Medicine of the Pacific – Northwest
2. David Beckett OMS I – Western University of Health Sciences – College of Osteopathic Medicine of the Pacific – Northwest
3. Marc Davidson MD – Advantage Orthopedic & Sports Medicine

Abstract

Proximal tibiofibular joint (PTFJ) dislocations are a rare type of lower extremity injury often resulting from direct trauma to the joint. Due to the rarity of the injury and the lack of controlled studies, there is no current best treatment practice. This case study presents a review of the anatomy of the joint, injury, diagnosis, and a successful surgical approach with double-spanning diverging suture fixation to treat a PTFJ dislocation. The double-spanning diverging suture technique used in this case achieved stabilization of the joint in an anatomic manner while avoiding a rigid construct that limits the natural mechanics of the joint and additional surgery to remove fixation devices.

Keywords: Proximal tibiofibular joint dislocation, ski injury, treatment with double spanning diverging sutures, diagnosis and treatment for proximal tibiofibular joint dislocation

Introduction
The proximal tibiofibular joint (PTFJ) is a plane-type synovial joint formed by a flat facet on the posterolateral aspect of the lateral tibial condyle and a similar flat facet on the fibular head.¹ The posterolateral ligamentous corner and the anterior and posterior tibiofibular ligaments stabilize the joint.² The purpose of the joint is to dissipate torsional stresses applied at the ankle and tensile forces during weight-bearing.³

Two types of PTF joints, oblique and horizontal, were identified by Ogden’s anatomical studies in 1974, with the oblique form having the least area of articular surface and the higher chance of dislocating. Ogden also described four types of injury to the PTFJ, including subluxation, anterolateral dislocation, posteromedial dislocation, and superior dislocation.⁴ Anterolateral dislocation is the most common, and it is often seen in sports injuries involving a fall or twist with the ankle inverted and the knee flexed. A posteromedial dislocation is more commonly seen in cases with direct fibular head trauma.⁵  

Overall rates of PTFJ dislocation remain rare, frequently reported to make up approximately 1% of all knee injuries.^2,6 Common associated injuries with PTFJ dislocation include lateral meniscus tear, lateral tibial plateau fractures, tibial shaft fractures, and common peroneal nerve injury.^3,7

Diagnosis of PTFJ dislocation is made via a combination of physical exam findings and various imaging modalities, including plain film radiographs, CT, and MRI scans. Physical exam findings that may be present include prominence and tenderness of the fibular head, pain with weight-bearing that worsens with squatting, and altered sensation over the common peroneal nerve distribution.⁸ Anterior to posterior (AP) and lateral views of both knees are recommended as the first imaging study. CT scans can be useful to delineate proximal tibial fractures, but the indications for using CT for evaluation of isolated PTFJ dislocations are not well established.² MRI imaging use has been advocated for in the setting of PTFJ dislocation to evaluate the tibiofibular ligaments, common peroneal nerve, and associated intra-articular knee pathology.^3,7

Treatment of PTFJ dislocation varies from reduction to surgical intervention. Initial treatment of acute PTFJ dislocation is closed reduction of the joint under intravenous sedation or with a local anesthetic.² In the cases of chronic instability, proposed treatments include arthrodesis with fibular osteotomy, temporary and permanent screw fixation,⁸ autograft reconstruction,⁹ and temporary fixation with Kirschner wires.^6,10 Optimal surgical treatment is currently unknown given the rarity of this injury and the lack of large controlled studies. However, flexible fixation has been described to avoid adverse effects by avoiding the necessity of a second surgery to remove fixation devices and avoiding malreduction of normal external rotation and anteroposterior translation of the fibula caused by rigid fixation constructs.¹⁰ Arthrodesis and fibular head resection are no longer advocated for as they have been shown to cause postoperative instability as well as knee and ankle pain.⁹

In this case study, we present a case of a professional skier presenting to the clinic with an acute injury with unstable PTFJ and a surgical repair with double-spanning diverging suture fixation devices.

Case Presentation
A 34-year-old male professional ski instructor presented to the clinic with left knee pain secondary to a skiing injury in which his proximal lateral knee collided with the blunt end of a metal railing during a jump. He presented to an urgent care for initial evaluation where plain film radiographs of his left knee were unremarkable. He was subsequently referred for further orthopedic evaluation. His complaints were sharp pain over the lateral aspect of his knee, worse with descending stairs and squatting.

Exam
On physical examination, the left knee appeared grossly anatomic with no acute deformities. There was a trace to small effusion, minimal tenderness over the lateral joint line, and exquisite tenderness over the fibular head. The PTFJ was hypermobile and easily subluxated on exam in contrast to the uninjured knee. The cruciate and collateral ligaments were intact and symmetric. There was no tenderness over the medial structures of the knee or distally at the ankle. Active knee flexion was normal. The patient was able to actively dorsiflex and plantarflex. Sensation to light touch was intact in all lower extremity nerve groups. A clinical diagnosis of PTFJ dislocation was made, and an MRI scan of his left knee was obtained.

Imaging
Left knee MRI revealed a small radial tear at the junction of the anterior and mid-body of the lateral meniscus and partial tearing of the posterosuperior biceps femoris attachment. The PTFJ was horizontally oriented with edema over the proximal tibia cephalad to the proximal tibiofibular articulation and chondral irregularities on the tibial facet (Figure 1).

Treatment
An approach to stabilize the PTFJ with a double-spanning suture fixation was chosen. An arthroscopy was planned to examine and treat the lateral meniscus tear, followed by an open repair of the PTFJ.

Surgical Technique
Under general anesthesia, arthroscopy of the patient’s knee was performed, and the lateral meniscus tear was addressed with partial lateral meniscectomy. There were no other intra-articular injuries.

With the knee flexed to 90 degrees, a lateral incision was made centered on the lateral epicondyle and fibular head. The subcutaneous tissues were elevated off the fascia proximally and circumferentially to identify the IT band, inferior border of the biceps femoris, and fibular head. The common peroneal nerve was palpated and identified to protect it. With the joint manually reduced, a guidewire was placed across the posterior tibiofibular joint with the pin exiting the anteromedial tibial cortex allowing some tenting of the skin. After over drilling with a cannulated drill, a flexible suture was used for fixation. A medial incision was made to avoid entrapment of the saphenous nerve, and the button was ensured to be on the tibial cortex. A second anchor was then placed across the joint more anteriorly using a similar technique. The flexible suture fixation device button exited the medial tibial cortex adjacent to the tibial tubercle, ensuring the infrapatellar nerve was not trapped under the button. This technique resulted in two diverging sutures spanning the joint (Figure 2). With both anchors loosely in place, they were gently tensioned, eliminating the gross mobility of the PTFJ. Intraoperative fluoroscopy was used to ensure correct placement of the fixation devices, and intraoperative laxity was eliminated.

The injured posterosuperior portion of the biceps femoris attachment on the fibular head was repaired back to the arcuate ligament. The wound was then closed in layers.

Post-op Management and Outcome
At the first postoperative visit, AP and lateral plain film radiographs of the knee were obtained, showing flexible suture fixation of the PTFJ with the metallic implants in a good position (Figure 3). The patient was non-weight bearing with crutches and no knee brace for one month. After the first month, progressive weight-bearing and weaning off crutches. Physical therapy was prescribed for a supervised knee range of motion, quadriceps/hamstring stretching, and strengthening program. At three months, the patient was entirely off of crutches and began in-line impact activities with no cutting or pivoting. At four months, he was released to ski gentle runs, and at five months, the patient was skiing aggressively and performing 50 foot jumps with no reports of instability.

Discussion
PTFJ dislocations may be challenging to diagnose and missed due to variable clinical presentation and their rare incidence. There should be high suspicion for a PTFJ dislocation when there is an instance of trauma to the lateral aspect of the knee or when the patient is involved in sporting activities with high-intensity cutting and pivoting movements. These dislocations can often be initially mistaken for an isolated lateral meniscus tear due to their anatomic proximity and similarity in symptoms, including pain near the lateral joint line and a catching sensation.¹¹ Another possible finding on examination is paresthesia in the common peroneal nerve distribution due to the nerve laying adjacent to the fibular head and the possibility of injuring it during a dislocation.⁸

In the presented case study, the mechanism of injury, the tenderness with palpation over the proximal fibular head, and comparative anterolateral subluxation of the joint on examination led to a tentative diagnosis of PTFJ dislocation that was confirmed through MRI. The technique to test the instability of the joint involves grasping the fibular head between the thumb and index finger and translating it anterolaterally while the patient is in a supine position with the knee flexed to 90 degrees and the biceps femoris relaxed.¹² This technique should be repeated on the uninjured knee to compare laxity in the joint.

A cadaveric study performed by Keogh et al. found an 82% accuracy rate in diagnosing PTFJ dislocation when using knee AP, lateral, and bilateral comparison radiographs together.¹³ This finding indicates that these radiographic views are a cost-effective and quick, accurate method to aid in the diagnosing of acute PTFJ dislocations.

PTFJ dislocation is treated in various ways with no current best technique due to a lack of controlled studies. One observed practice is closed reduction of the joint in acute settings. Several case studies report isolated dislocations of the joint with minimal to no soft tissue injury.^2,5,6,8 However, surgical intervention may be considered for patients that present with chronic instability when treated conservatively or when other soft tissue injuries accompany PTFJ dislocations.

We report using two diverging suture buttons to repair an acute PTFJ dislocation. This approach appeared advantageous for several reasons. First, a cadaver study by Westermann et al. found that using a suture button fixation compared to a screw fixation performed better at minimizing malreductions of the syndesmosis.¹⁴ Second, another case report promoted that suture button fixation also avoids a second procedure to remove fixation.⁶ Third, the diverging angle and use of two suture buttons would eliminate a rotational axis that could be seen with a single suture button and reduce the risk of unwarranted movement.

Conclusion
While there is still limited evidence on the best surgical technique for PTFJ dislocations, our case and others in the literature have utilized suture button fixation to treat this injury. Our case reports another successful surgical approach of an acute PTFJ dislocation with double-spanning suture fixation in a diverging fashion. The patient recovered with no complications and was able to return to his pre-injury level of activity. Further controlled studies need to be conducted to determine the long-term outcomes of this technique.

References

1. Moore KL, Agur AMR, Dalley AF. Chapter 5: Lower limb. In: Moore’s Essential Clinical Anatomy. 5th ed. Philadelphia, PA: Lippincott Williams&Wilkins; 2015:379-381.
2. Cunningham NJ, Farebrother N, Miles J. Review article: Isolated proximal tibiofibular joint dislocation. Emergency Medicine Australasia. 2018;31(2):156-162. doi:10.1111/1742-6723.12989.
3. Sarma A, Borgohain B, Saikia B,. Proximal tibiofibular joint: Rendezvous with a forgotten articulation. Indian Journal of Orthopaedics. 2015;49(5):489-495. doi:10.4103/0019-5413.1640414.
4. Ogden J. Subluxation and dislocation of the proximal tibiofibular joint. The Journal of Bone&Joint Surgery. 1974;56(1):145-154. doi:10.2106/00004623-197456010-00015.
5. Krukhaug Y, Schrama JC. Acute traumatic proximal tibiofibular dislocation: Treatment of three cases. Journal of Orthopaedic Case Reports. 2019;9(1):98-101. Doi:2250-0685.1328.
6. Moscon AC, Cabrera Martimbianco AL, Duarte Junior A, Gracitelli GC. Proximal tibiofibular joint dislocation treated using flexible and permanent syndesmosis fixation. BMJ Case Reports. 2018:1-4. doi:10.1136/bcr-2017-222843.
7. Tanrıverdi B, Erçin E, Edipoğlu E, Kural C. Proximal tibiofibular dislocation accompanied by bucket-handle meniscal tear: Case report. Joint Diseases and Related Surgery. 2020;31(3):634-638. doi:10.5606/ehc.2020.71630.
8. McDaniel D, Linneman K, Main DC. Surgical Treatment Of Proximal Tibiofibular Joint Instability Using Dynamic Fixation With Two Tightropes In Diverging Fashion And Bioabsorbable Cortical Screw Fixation. The Internet Journal of Orthopedic Surgery. 2018;26(1):1-5. doi:10.5580/IJOS.53116.
9. Warner BT, Moulton SG, Cram TR, LaPrade RF. Anatomic reconstruction of the proximal tibiofibular joint. Arthroscopy Techniques. 2016;5(1):207-210. doi:10.1016/j.eats.2015.11.004.
10. McNamara WJ, Matson AP, Mickelson DT, Moorman CT. Surgical management of proximal tibiofibular joint instability using an adjustable loop, cortical fixation device. Arthroscopy Techniques. 2018;7(3):271-277. doi:10.1016/j.eats.2017.09.003.
11. Nieuwe Weme RA, Somford MP, Schepers T. Proximal tibiofibular dislocation: a case report and review of literature. Strategies Trauma Limb Reconstr. 2014;9(3):185-189. doi:10.1007/s11751-014-0209-8.
12. Sijbrandij S. Instability of the proximal tibio-fibular joint. Acta Orthop Scand. 1978;49(6):621-626. doi:10.3109/17453677808993250.
13. Keogh P, Masterson E, Murphy B, McCoy CT, Gibney RG, Kelly E. The role of radiography and computed tomography in the diagnosis of acute dislocation of the proximal tibiofibular joint. Br J Radiol. 1993;66(782):108-111. doi:10.1259/0007-1285-66-782-108.
14. Westermann RW, Rungprai C, Goetz JE, Femino J, Amendola A, Phisitkul P (2014) The effect of suture-button fixation on simulated syndesmotic malreduction: a cadaveric study. J Bone Joint Surg 96:1732-1738.

Figure Legends
Figure 1. Left knee coronal and transverse views of the patient’s injured left knee. The image shows an increased signal in the proximal tibial facet and surrounding soft tissues.

Figure 2. Cross-section diagram of the left proximal tibiofibular joint. The image shows the placement of the flexible suture fixation device indicated by the black lines and blue rectangles on the tibia and fibula. Basic anatomy of the joint is also included showing 1) tibia, 2) fibula, 3) extensor digitorum longus, 4) tibialis anterior, 5) tibialis posterior, 6) soleus, 7) lateral head of gastric, 8) medial head of gastric, 9) common peroneal nerve, 10) tibial nerve, 11) saphenous nerve and vein, 12) posterior tibial artery and veins, 13) patellar tendon, 14) sartorius, 15) medial collateral ligament, 16) semitendinosus tendon, 17) gracilis tendon, and 18) skin envelope.

Figure 3. AP and lateral postoperative plain film radiographs of the left knee. Metallic implants can be seen on both the fibular head and medial aspect of the proximal tibia. The implants are slightly offset vertically to increase stability.