OSSIOFiber

Introduction

The subtalar joint (STJ), also known as the talocalcaneal joint, is a complex articulation between the talus superiorly and the calcaneus inferiorly1,2. It plays a major role in inversion and eversion of the foot by load transmission and movement at the hindfoot1,2. 

Traumatic injury to the STJ disrupts normal hindfoot motion and thus may significantly restrict global foot function. Pain originating from the STJ might result from several pathologies, including primary arthritis, posttraumatic arthritis, congenital or acquired deformities, instability, tarsal coalition or inflammatory diseases3. Osteoarthritis can develop in a damaged and distorted STJ, and this complication is the main cause of late and prolonged disability4. 

Once conservative treatment has failed, subtalar arthrodesis using 2-3 screws is the gold standard treatment, which offers pain relief for weightbearing activities. Common complications of this fusion procedure include wound infections, sensory deficits, persisting pain, as well as non-union, which may require revision surgery. Wirth et al. showed that risk factors for non-union of STJ fusions are smoking or alcoholism history, diabetes, coexisting psychiatric diseases, prior ankle-fusion, persisting infections or revision surgery. Diabetes mellitus was found to be associated with higher rate of STJ revision arthrodesis, as 56% of the patients with diabetes underwent revision vs. 22% of the patients without diabetes3.

Case History

A female patient in her early 50s, BMI of 31.3, diagnosed with type 2 diabetes. The patient suffered a traumatic 30 feet fall. She presented a four-level spinal trauma that resulted in surgical spinal fusion. She further suffered a right open calcaneal fracture that was debrided and saturated closed without surgical fixation attempt. The patient presented chronic right foot and heel pain, leading to immobility and weight gain for the next four years.

Case Presentation

Upon meeting and assessing the patient, it was noted she had a large osseous bulge on the plantar aspect of the right heel. She had a short cadence and demonstrated an ataxic gait. She complained of pain that radiated from the plantar calcaneus along the posterior heel and extended to the Achilles aponeurosis.

CT scan was performed to evaluate the posterior facet of the STJ and prior fracture pattern. Imaging demonstrated post traumatic deformity of the calcaneus with minimal scattered regions of osseous non-union and mild STJ osteoarthritis.

Why is OSSIOfiber® an Ideal Choice for This Patient?

Based on the patient’s medical history of diabetes, there was a great benefit in using OSSIOfiber® implants and void hardware removal procedure in the future. Furthermore, traditionally, posterior calcaneal screws need to be removed quite often, thus the use of non-permanent implants avoids this inherent risk.

Figure 1: Pre-operative X-rays; lateral [A], AP [B] and Oblique[C]

Surgical Plan

Right STJ arthrodesis with callus distraction, lateral calcaneal wall decompression and tendon repair. Leg Length Radiograph Measuring was used for operative planning of the distraction arthrodesis.

The following OSSIOfiber® fixation implants were used:

• OSSIOfiber® Cannulated Trimmable Fixation Nail (CTFN) 4.0x70mm x 1 unit
• OSSIOfiber® Compression Screw (CS) 4.0x60mm x 2 units
• OSSIOfiber® Suture Anchor (SA) 4.75 x 2 units
• Iliac Crest Wedges (Tricortical Blocks) by MTF Biologics

Surgical Technique

The surgeon chose to operate on the patient in two positions.

Initially, in a prone position, this afforded direct access to the posterior STJ. Using a Hintermann retractor, the surgeon was able to measure the amount of distraction needed. Then, a Tricortical Allograft Block was fashioned and placed in the posterior facet of the STJ. Next, imaging was used to confirm block position, and the OSSIOfiber® CTFN was inserted across the STJ from the dorsal to plantar surface. Then, two 4.0 OSSIOfiber® CS were inserted from the posterior calcaneus to the talar neck and talar head. Both screws and nail crossed the joint and through the tricortical block. The incision site was closed and sutured.

Next, the patient was moved into a supine position, allowing access to the lateral wall of the calcaneus, Peroneus Brevis tendon, Peroneus Longus tendon, and fibula. After realignment of the anatomy, an aggressive arthroscopic ankle debridement was done, including removal of multiple exostosis from the anterior tibial plafond, which worsened over time by her impingement on ambulation during the past couple of years since the trauma. Tendon was advanced and reattached using two OSSIOfiber® SA.

Post-Operative Protocol

• Non-weight bearing: 4 weeks in a Short Leg Cast
• Partial weight bearing: 2 weeks in a CAM boot
• Full weight bearing: At 6 weeks started physical therapy
• Comfort Show: At 7 weeks post op

Patient Follow-up

The surgeon noted less swelling compared to this experience with other patients treated with metal hardware for STJ fusion. No complications reported throughout the duration of the post operative healing.

Figure 2: 8 weeks post-operative X-rays; Lateral [A], Posterior ankle [B] and Oblique [C]