Injury and Patient Characteristics
All four individuals included in this series were men on active duty with the United States military. The average age at the time of surgery was 27.75 (range, twenty-two to thirty-two years). All surgeries were performed by a single surgeon (R.R.B.). Three patients initially had a Berndt and Harty Stage-I lesion, and, for each of these patients, previous treatment with arthroscopic debridement and microfracture had failed (Figs. 1-A, 1-B, and 1-C). One individual had a primary Stage-V cystic lesion2,16.
The mean time from the last surgery to revision with the TRUFIT plug was 33.6 months (range, five to eighty-four months). The patient who received the TRUFIT plug as the primary intervention had undergone twelve months of conservative management, including activity modification and a trial of physical therapy, prior to undergoing surgery. The decision to use the TRUFIT plug in these four patients was based on the prior failure of marrow-stimulating procedures and/or the large size of the lesion. Our hypothesis was that the TRUFIT plug would eliminate the risk of autograft donor-site morbidity and potentiate a more rapid return to activity.
Surgical Technique
The surgery was performed through a longitudinal J-type incision overlying the medial aspect of the distal part of the tibia. A chevron osteotomy of the medial malleolus was performed to facilitate visualization of the talus17. On completion of the osteotomy, the osteochondral lesion was identified and measured. The lesion was then reamed with an appropriately sized reamer to a depth of 10 to 13 mm, ensuring removal of the underlying sclerotic cyst rim. A biosynthetic osteochondral implant was then cut to the appropriate size. The implant was placed into the talus, flush with the chondral surface. After the wound was irrigated copiously with sterile saline solution, the ankle was moved through a gentle range of motion to ensure that the graft did not impinge on the distal aspect of the tibia. The medial malleolar osteotomy was repaired with use of 4.0-mm cannulated screws, and the incision was closed in layers.
All patients were rehabilitated using the same postoperative protocol. Patients were evaluated at two weeks, six weeks, three months, six months, twelve months, and fifteen months. The operative limb was immobilized for the first two weeks in a plaster splint. Following removal of the sutures at two weeks, a short leg cast was used for another four weeks to allow full healing of the malleolar osteotomy. Physical therapy, including ankle range-of-motion and ankle-strengthening exercises, was initiated at six weeks postoperatively. All patients remained non-weight-bearing for eight to twelve weeks to prevent excessive load transmission across the ankle while graft incorporation occurred.
Complications and Additional Surgeries
At the two and six-week follow-up visits, all four patients reported reduced pain compared with the level of pain reported preoperatively. By three months, all patients began to have increased ankle pain, and a return to preoperative pain levels occurred at an average of six months after surgery (range, four to nine months). All patients subsequently demonstrated clinical and radiographic evidence of implant failure (Figs. 2-A, 2-B, and 2-C). At the time of failure, magnetic resonance images demonstrated increased signal within the talus, indicative of subchondral edema. Additionally, the images demonstrated a lack of homogeneity between the talus and the implant, evidenced by a dense sclerotic rim surrounding the graft. The average time to failure following surgery was nine months (range, five to twelve months).
Each patient was offered further treatment to address the recurrent pain and disability. One patient refused and requested medical discharge from the Army. A second patient refused revision surgery but remained on active duty. The remaining two patients underwent bulk allograft transplantation as a salvage procedure. During the salvage operation, the biosynthetic graft appeared yellow in comparison with the color of the surrounding healthy articular cartilage (Fig. 3-A). The implant area consisted of soft fibrous tissue with a hard sclerotic rim surrounding the biosynthetic graft (Fig. 3-B). Histologic sections demonstrated fibro-osseous and chondroid tissue with evidence of vascular proliferation and a mixed inflammatory response.
Final Result
At the time of final follow-up after the salvage procedure (mean, 30.5 months; range, twenty-five to thirty-six months), the two patients who underwent bulk allograft transplantation had mild reduction in ankle pain. Despite these improvements, both individuals reported continued pain with high-impact or prolonged repetitive physical activity. One patient remained on active duty but with physical restrictions. The other service member had been medically discharged from the Army at nineteen months following implantation of the biosynthetic scaffold.
The one patient who remained on active duty following biosynthetic graft implantation was able to perform only low-demand duties and continued to have chronic ankle pain.
The treatment of recurrent or large osteochondral lesions of the talus has challenged orthopaedic surgeons since the first description of these lesions in 19591. Although many techniques have been proposed to treat these lesions, each is associated with substantial limitations. Several reports support the use of osteochondral autograft; however, donor-site morbidity as well as the fixed amount of graft tissue available for use limits the use of osteochondral autograft in larger lesions18,19. Fresh-frozen or freeze-dried osteochondral allografts have the capability to address larger lesions, but concerns about disease transmission, immune response, chondrocyte viability, and graft availability have prompted clinicians to explore alternative solutions20,21.
In response to these limitations, biosynthetic scaffold implants have been proposed as a viable alternative15. Theoretically, the scaffold provides a three-dimensional platform for the proliferation of chondrocytes and the regeneration of native tissue while maintaining the appropriate shape and articular surface20.
Niederauer et al. examined the mechanical and physical properties of multiphase implants and their impact on the healing response of cartilage in a goat model22. Four different multiphase scaffold implants were utilized, and all were found to demonstrate the potential for successful treatment of osteochondral defects. Davidson and Rivenburgh presented satisfactory results in a series of patients treated with orthobiologic scaffold grafts for osteochondral defects in the knee23, while Williams and Gamradt documented successful incorporation of these constructs in the distal part of the femur15.
Although the preliminary reports regarding the use of biosynthetic scaffolds in the knee are encouraging, there is limited clinical evidence for similar applications in the talus. Hardy and Sharpe described the use of a biosynthetic scaffold for the treatment of primary osteochondral lesions of the talus, but they did not address clinical outcomes24.
To our knowledge, this series represents the first report to address outcomes in patients treated with a biosynthetic scaffold for a complex osteochondral talar lesion; the results presented here may indicate that biosynthetic scaffolds have limited clinical effectiveness in the treatment of these lesions. It is possible that our findings differ from those of Davidson and Rivenburgh23 due to a difference in anatomic location. The work of Davidson and Rivenburgh entailed the use of biosynthetic scaffolds in a non-weight-bearing location within the knee joint. In contrast, we utilized the scaffold in a weight-bearing portion of the talus.
Additionally, a few recently published papers have identified complications with graft incorporation. Sgaglione and Florence described the cases of two patients in whom osteochondral lesions of the knee were treated with biosynthetic grafts. The grafts in both patients failed to incorporate and stimulated a giant-cell response25. Carmont et al. recommended monitoring of graft incorporation for as long as twenty-four months postoperatively26. However, prolonged monitoring in the presence of continued pain and dysfunction is often not an option for patients in the military, as duty requirements limit the amount of time that can be spent away from a position.
We theorize that our patients experienced graft failure due to the inherently higher joint reaction forces that are imparted on the implant within the ankle joint. Moreover, the fact that active-duty soldiers are less able to limit their physical activities may have placed the talar grafts at a greater risk of failure. Further research needs to be conducted regarding biosynthetic grafts and their potential role in the treatment of osteochondral lesions of the talus. As new materials are developed, it may be possible to develop scaffolds that have a more robust structure that can better withstand the forces that are present in the ankle. At the present time, on the basis of the results presented in this series, we caution against the use of biosynthetic scaffolds for the treatment of osteochondral lesions of the talus, especially in high-demand populations such as active-duty service members or civilian high-performance athletes. Additionally, it may be prudent to avoid use of this implant for the treatment of talar lesions in all patient populations until additional clinical data supporting its use are available.