Osteochondrogenesis with Autologous Peripheral Blood Stem Cells for Osteochondral Lesions of the Talus: Report of Five Cases

Osteochondral lesions of the talus (OLTs) may progress to ankle arthritis needing ankle arthroplasty or arthrodesis. We report five cases of OLTs treated along the principles developed for chondrogenesis of the knee joint with autologous peripheral blood stem cells (PBSCs), resulting in repair and regeneration of the bone and cartilage components. Improvement in Ankle Osteoarthritis Scale (AOS) scores with minimum two years follow-up showed statistical significance (p < 0.05).


INTRODUCTION
Osteochondral lesions of the talus (OLTs) involve injury to the ankle articular cartilage and the underlying subchondral bone, often associated with ankle pain and dysfunction. Left untreated, OLTs risk progression to ankle arthritis needing ankle arthroplasty or arthrodesis.
We developed arthroscopic K.A.R.T. (KLSMC Articular Regeneration Technology) to address massive knee chondral defects 1 and end-staged ankle arthritis 2 . Applying the same principles developed for chondrogenesis with autologous peripheral blood stem cells (PBSCs), we report the results of applying K.A.R.T. to address OLTs by repair and regeneration of the bone and cartilage components.

CASE REPORTS
The first case was a 17-year-old female teenager presented with a 3 years' history of left ankle pain following an injury sustained at ballet. The pain was aggravated by prolonged walks and running. MRI scan (Fig. 1a, 1b) revealed an osteochondral lesion of the medial talar dome measuring 0.9cm length (L) x 0.5cm width (W) x 0.8cm depth (D). Arthroscopic removal of the loose osteochondral fragment was performed followed by subchondral drilling into the defect (Fig. 1c, 1d) as previously described 1-3 .
One week after surgery, PBSCs were harvested. The details of the harvesting procedure and cell preparation are outlined in our previous publication 3 . Immediately after the apheresis process, 8ml fresh PBSCs aliquot was mixed with 2ml hyaluronic acid (HA) and injected into the operated ankle joint under aseptic conditions. Haemarthrosis was aspirated prior to each injection. At 4 subsequent weekly intervals, an 8ml aliquot of the thawed cryopreserved PBSCs mixed with 2ml HA were injected into the operated ankle joint. Physiotherapy with joint mobilisation commenced one day after surgery. Partial weight bearing progressed from day one after surgery to full weight bearing in six weeks. At month 6, 12, 18 and 24 following surgery, 3 additional weekly intraarticular injections comprising 4ml thawed cryopreserved PBSCs and 2ml HA were given. MRI of the left ankle performed one day after surgery (Fig. 1e, 1f) showed the removed loose osteochondral fragment and subchondral drilling without bone grafting. Corresponding images at two years, (Fig. 1g, 1h) showed osteochondral regeneration and integration. Patient returned to sporting activities at two years after surgery.

Osteochondrogenesis with Autologous Peripheral Blood Stem Cells for Osteochondral Lesions of the Talus: Report of Five Cases
Second case was a 33-year-old man who presented with a 4 years' history of right ankle pain following recurrent ankle sprains from basketball. MRI scan (Fig. 2a, 2b) revealed an osteochondral lesion of the lateral talar dome measuring 1.2cm (L) x 1.3cm (W) x 0.8cm (D). Osteochondral regeneration is clearly observed from MRI images (Fig. 2c, 2d) at two years after surgery.
Third case was a 50-year-old woman who sustained a skiing injury and presented with a 4 years' history of right ankle pain. MR images of her right ankle (Fig. 2e, 2f) revealed an osteochondral lesion of the medial talar dome measuring 0.7cm (L) x 0.5cm (W) x 0.5cm (D). MR images at two years (Fig. 2g, 2h) showed satisfactory healing.
The surgical procedures and post-operative management of the above cases were similar to the first case. Written informed consent was taken from all cases reported here. There were no documented infection or major adverse events.

DISCUSSION
The results of this case series showed the ability of K.A.R.T. to repair and regenerate both the articular cartilage and the underlying subchondral bone of OLTs with clinical and radiological improvements, supporting the application of PBSCs for osteochondrogenesis.