Cartilage allograft transplantation for challenging medial talar dome osteochondral defects: A retrospective case series utilizing medial malleolar osteotomy

Abstract

BACKGROUND

Osteochondral defects (OCDs) of the medial talar dome represent a complex surgical challenge due to limited arthroscopic accessibility. Medial malleolar osteotomy allows optimal access for cartilage restoration in challenging medial talar dome lesions. This case series examines the clinical and radiographic outcomes of treating medial talar OCDs with the cartilage allograft following arthroscopic evaluation and medial malleolar osteotomy.

AIM

To evaluate the clinical and radiographic outcomes of treating large, symptomatic medial talar dome OCDs using a single-stage technique combining medial malleolar osteotomy, bone marrow aspirate augmentation, and cartilage allograft transplantation. We assessed functional improvement using validated outcome measures and graft integration using magnetic resonance imaging (MRI)-based Magnetic Resonance Observation of Cartilage Repair Tissue scoring at midterm follow-up.

METHODS

A retrospective analysis was conducted on 23 consecutive patients (mean age 35.4 years; 15 males, 8 females) presenting with symptomatic, isolated OCDs of the medial talar dome (Raikin zone 4) after failed conservative management. Each patient underwent arthroscopic evaluation followed by medial malleolar osteotomy, systematic defect preparation with drilling, bone marrow aspirate application, and the cartilage allograft implantation secured with fibrin glue. Clinical assessment utilized the American Orthopaedic Foot and Ankle Society ankle-hindfoot score, Short Form-36, and Visual Analogue Scale for pain at mean 24-month follow-up. Pre and post operative radiographic and MRI was used to evaluate graft integration and fill.

RESULTS

The mean American Orthopaedic Foot and Ankle Society score demonstrated improvement from 54.2 ± 12.1 preoperatively to 88.7 ± 7.5 postoperatively (P < 0.001). Mean Visual Analogue Scale pain scores decreased from 6.4 ± 1.0 to 1.5 ± 1.2 (P < 0.001). Short Form-36 scores exhibited significant enhancement across all domains. Eighteen of 23 patients (80%) achieved good to excellent outcomes. Five patients experienced residual mild pain, though substantially improved from preoperative status. Postoperative MRI revealed complete or substantial graft fill and integration in 20 of 23 patients (87%). Complications included one delayed union of the osteotomy and two superficial wound complications which resolved with conservative management.

CONCLUSION

Treatment of symptomatic OCDs of the medial talar dome with cartilage allograft following medial malleolar osteotomy represents a safe and effective procedure, yielding significant clinical and radiographic improvements at midterm follow-up. This single-stage procedure offers a promising therapeutic option for these challenging lesions. Long-term follow-up remains necessary to assess repair durability and outcomes.

Key Words: Osteochondral lesions; Talus; Medial malleolar osteotomy; Cartilage allograft; Fibrin glue; Case series

Core Tip: This retrospective study evaluated 23 patients with symptomatic osteochondral defects of the medial talar dome treated using cartilage allograft transplantation following medial malleolar osteotomy. The technique combined defect drilling, bone marrow aspirate application, and fibrin glue fixation to enhance graft stability and integration. Significant improvements were achieved in American Orthopaedic Foot and Ankle Society score, Visual Analogue Scale for pain, and Magnetic Resonance Observation of Cartilage Repair Tissue score. This single-stage approach provides a safe, effective, and biologically supported solution for large medial talar dome osteochondral defects.

INTRODUCTION

Osteochondral defects (OCDs) of the talus constitute a challenging clinical entity affecting both athletic populations and the general public. These lesions, alternatively termed osteochondral lesions of the talus, may result from acute traumatic events or repetitive microtrauma and demonstrate frequent association with ankle sprains and chronic ankle instability[1,2]. The reported incidence of talar OCDs ranges from 6.5% to 74% in patients sustaining acute ankle fractures, underscoring the substantial clinical burden of this pathology[3].

The anatomical complexity of the ankle joint and distinctive characteristics of talar cartilage present unique management challenges. The talus receives vascular supply from multiple sources, with the talar body being particularly susceptible to avascular necrosis due to its retrograde blood supply pattern[4]. Additionally, the highly congruent nature of the ankle joint restricts accessibility to specific areas of the talar dome, particularly the posteromedial aspect, corresponding to zone 4 in the established 9-zone anatomical grid system described by Raikin et al[5]. Preoperative imaging evaluation is crucial for accurate diagnosis and surgical planning in patients with suspected talar OCDs. Magnetic resonance imaging (MRI) remains the gold standard for assessment of cartilage integrity, subchondral bone involvement, and precise lesion localization within the 9-zone grid system. High-resolution T2-weighted sequences in multiple planes provide optimal visualization of the OCD characteristics, including the extent of cartilage damage, presence of subchondral cysts or sclerosis, and surrounding bone marrow edema patterns. The combination of coronal, sagittal, and axial imaging planes allows for comprehensive three-dimensional assessment of lesion morphology and facilitates accurate preoperative planning for the optimal surgical approach (Figure 1).

Figure 1 Preoperative magnetic resonance imaging demonstrating osteochondral defect of the medial talar dome (Raikin zone 4). A: Coronal T2-weighted image showing the defect with surrounding bone marrow edema; B: Sagittal T2-weighted image demonstrating the depth and extent of the lesion; C: Axial T2-weighted image showing the medial location of the defect directly lateral to the medial malleolus.

The classification systems for talar OCDs have undergone significant evolution over recent decades. The traditional Berndt and Harty[6] classification, based on plain radiographic findings, has been supplemented by MRI-based classification systems including the Hepple et al[7] classification, which provides enhanced assessment of cartilage integrity and subchondral bone involvement. More recently, the 9-zone grid system has gained widespread acceptance as it provides precise anatomical localization facilitating surgical planning and inter-surgeon communication[8].

Treatment modalities for talar OCDs depend on the lesion size, location and stability characteristics. Conservative treatment remains appropriate for stable, non-displaced lesions and may include activity modification, immobilization, and physical therapy protocols. However, symptomatic lesions, particularly those demonstrating instability or conservative treatment failure, frequently require surgical intervention[9].

Arthroscopic techniques have emerged as the preferred approach for treating talar OCDs due to their minimally invasive nature and superior visualization capabilities. Nevertheless, accessibility to certain talar dome regions remains limited with standard arthroscopic approaches. Studies demonstrate that only 48% to 60% of the talar dome can be accessed through anterior arthroscopy, with the posteromedial aspect presenting particular accessibility challenges[10,11]. This limitation has prompted development of various open surgical approaches, including medial malleolar osteotomy, which provides excellent medial talar dome exposure at the expense of increased surgical morbidity[12].

The management approach for talar OCDs is significantly influenced by lesion size, with larger defects (> 1.5 cm²) presenting particular challenges for arthroscopic treatment and demonstrating inferior outcomes with traditional bone marrow stimulation techniques[2,13]. Large medial talar dome OCDs, particularly those exceeding 1.5 cm² in area, often require open surgical approaches due to the combination of limited arthroscopic accessibility and the need for robust cartilage restoration techniques capable of addressing substantial defects[14].

Recent advances in cartilage repair technology have introduced novel therapeutic options. The cartilage allografts represent an emerging frontier in cartilage restoration, offering potential advantages of containing living chondrocytes and native extracellular matrix while avoiding autograft harvest morbidity[15]. Contemporary research has demonstrated promising outcomes with various cartilage repair techniques, with recent systematic reviews highlighting the importance of lesion location and size in treatment selection[14,15].

MATERIALS AND METHODS

This study represents a retrospective analysis of 23 consecutive patients who underwent surgical treatment for symptomatic OCDs of the medial talar dome between January 2020 and December 2022 at a tertiary care trauma center.

Inclusion and exclusion criteria

Inclusion criteria: (1) Age 18-60 years; (2) Symptomatic, isolated OCD of the medial talar dome (Raikin zone 4) confirmed on MRI; (3) Failed conservative treatment for minimum 6 months, including activity modification, physical therapy, and nonsteroidal anti-inflammatory medications; and (4) Minimum 12-month follow-up.

Exclusion criteria: (1) Previous ankle surgery; (2) Inflammatory arthritis; (3) Significant ankle instability or malalignment; and (4) Concomitant ankle pathology requiring surgical intervention.

Surgical technique

All procedures were performed by a single experienced foot and ankle consultant to ensure technical consistency. Patients were positioned supine with thigh tourniquet application.

Diagnostic arthroscopy

Standard diagnostic ankle arthroscopy was performed utilizing basic arthroscopic instrumentation without specialized equipment requirements. Standard anteromedial and anterolateral portals were established using a 4.0-mm arthroscope (Figure 2). The OCD underwent visualization with assessment of size, location, and stability characteristics. Cartilage integrity and loose fragment presence were evaluated. The decision to proceed with medial malleolar osteotomy was based on inability to achieve perpendicular lesion access for adequate debridement and graft implantation through arthroscopic means alone.

Figure 2  Diagnostic arthroscopy of the right ankle.

Medial malleolar osteotomy

Following arthroscopic assessment, a longitudinal incision was created over the medial malleolus, approximately 8-10 cm in length. The periosteum was carefully incised and elevated to preserve soft tissue attachments. The established medial malleolar osteotomy technique was performed according to literature standards[16]. Two parallel 2.7-mm drill holes were created from the medial malleolar tip proximally, exiting just above the tibial plafond under C-arm fluoroscopic guidance. The osteotomy was performed using an oscillating saw, connecting the drill holes and extending to, but not through, the articular cartilage. The osteotomy was completed with a sharp osteotome, creating a controlled fracture line (Figure 3). The medial malleolus was carefully reflected inferiorly on its soft-tissue hinge, preserving deltoid ligament attachments and providing excellent medial talar dome exposure (Figure 4).

Figure 3 Medial malleolar osteotomy technique. A: Completion of the osteotomy using a sharp osteotome after preliminary drilling and sawing; B: C-arm fluoroscopic confirmation of optimal osteotomy position and alignment before reflection of the malleolar fragment.

Figure 4  Surgical exposure after medial malleolar osteotomy showing excellent visualization of the osteochondral defect in the medial talar dome (Raikin zone 4) with the malleolar fragment retracted inferiorly.

Defect preparation and treatment

The OCD underwent thorough debridement with curettes and a rongeur to a stable base with underlying bleeding subchondral bone. The defect was prepared using 1.2-mm Kirschner wires for drilling, based on current literature recommendations for optimal bone marrow stimulation[17,18]. Multiple drill holes were created in the subchondral bone to approximately 4-6 mm depth, spaced 3-4 mm apart to ensure adequate bleeding and bone marrow access.

Following drilling, bone marrow aspirate was harvested from the ipsilateral iliac crest using a standard bone marrow aspiration needle and applied directly to the prepared defect bed. The aspirate was allowed to completely saturate the drilled holes for approximately 5 minutes to ensure optimal cellular seeding of the defect.

The rationale for bone marrow aspirate application lies in providing additional cellular support to optimize the biological environment for graft integration. Bone marrow aspirate contains mesenchymal stem cells, growth factors, and cytokines that enhance the regenerative potential of the prepared defect bed. The complete saturation protocol ensures optimal cellular seeding of the drilled subchondral bone, creating a biologically active foundation that promotes graft incorporation and long-term cartilage repair.

The defect was measured, and a corresponding-sized piece of the cartilage allograft was prepared according to manufacturer specifications. The allograft was mixed per protocol and shaped to match defect contours. The prepared allograft was then gently pressed into the defect, ensuring complete fill and appropriate contouring to match the surrounding cartilage surface.

Fibrin glue, a biological sealant, is composed primarily of concentrated fibrinogen and thrombin, which, upon mixing, replicate the final stage of the coagulation cascade to form a stable fibrin clot. Its application here serves a crucial mechanical role, providing immediate, secure fixation of the moldable cartilage allograft to the subchondral bone bed. This is particularly important for allograft materials that lack the rigidity for reliable press-fit fixation, ensuring the graft remains stable during the initial critical phase of integration. Fibrin glue was carefully applied over the graft for secure fixation. The fibrin glue was allowed to cure completely, typically requiring 10-15 minutes to ensure adequate polymerization and graft stability (Figure 5).

Figure 5 Allograft preparation and implantation. A: Surgeon holding the prepared allograft, appearing as a small, moldable ball ready for implantation; B: The allograft filling the prepared osteochondral defect, showing complete coverage and appropriate contouring.

Osteotomy reduction and fixation

After confirming graft stability, the medial malleolus was anatomically reduced under direct visualization. Two 2.0-mm guide wires were inserted under C-arm fluoroscopic guidance to ensure optimal positioning. Reduction was confirmed on orthogonal radiographs. Two 4.5-mm cannulated titanium screws were inserted over the guide wires to achieve stable osteotomy fixation (Figure 6). The wound was irrigated and closed in layers over a suction drain. Sterile dressing and short leg splint were applied.

Figure 6 Fluoroscopic images showing osteotomy fixation. Lateral ankle view demonstrating optimal positioning of two 4.5-mm cannulated titanium screws with anatomical reduction of the medial malleolus.

Postoperative protocol

Patients remained non-weight-bearing for 3 weeks, followed by 3 weeks of partial weight-bearing with assistive devices. Full weight-bearing was permitted at 6 weeks postoperatively. Early range-of-motion exercises were initiated at 2 weeks postoperatively. Patients were permitted to return to low-impact activities at 3 months and unrestricted activities, including sports, at 6-9 months, dependent upon clinical and radiographic progress.

Outcome measures

Clinical outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Short Form-36 (SF-36) health survey, and Visual Analogue Scale (VAS) for pain at preoperative and final follow-up visits. Radiographic evaluation included preoperative and postoperative MRI to assess graft integration and fill, utilizing the Magnetic Resonance Observation of Cartilage Repair Tissue score. Complications and reoperations were recorded. All postoperative MRI scans were independently evaluated by two orthopedic surgeons blinded to the patient’s clinical outcome. Inter-observer reliability was assessed using the interclass correlation coefficient, and a high level of agreement (interclass correlation coefficient > 0.80) was achieved.

Statistical analysis

Data were analyzed with IBM SPSS Statistics 25. Normality was tested using the Shapiro-Wilk test. Paired t-tests compared pre- and postoperative AOFAS, SF-36, and VAS scores. Significance was set at P < 0.05.

RESULTS

Basic characteristic

All 23 patients completed minimum 12-month follow-up, with mean follow-up of 24 months (range, 12-36 months). Mean patient age was 35.4 years (range, 19-58 years), with 15 male and 8 female patients. Mean OCD size was 1.8 cm² (range, 1.2-2.5 cm²), confirming that all patients in this series presented with large, surgically-indicated lesions.

Clinical outcomes

Mean AOFAS ankle-hindfoot score improved significantly from 54.2 ± 12.1 preoperatively to 88.7 ± 7.5 at final follow-up (P < 0.001). Mean VAS pain score demonstrated significant improvement, decreasing from 6.4 ± 1.0 preoperatively to 1.5 ± 1.2 at final follow-up (P < 0.001).

SF-36 scores demonstrated significant improvement across all eight domains (Table 1). The physical component summary improved from 38.2 ± 8.4 to 52.1 ± 6.7 (P < 0.001), and the mental component summary improved from 45.3 ± 9.2 to 54.8 ± 7.1 (P < 0.001). The most substantial improvements were observed in the role-physical domain (28.5 to 71.2, P < 0.001) and bodily pain domain (31.2 to 76.8, P < 0.001), reflecting the significant impact of successful surgical intervention on patients' functional capacity and pain relief.

Table 1 Short Form-36 domain scores, mean ± SD.

SF-36 domain	Preoperative	Postoperative	P value
Physical functioning	42.3 ± 8.7	78.4 ± 9.2	< 0.001
Role-physical	28.5 ± 12.4	71.2 ± 11.8	< 0.001
Bodily pain	31.2 ± 9.8	76.8 ± 8.4	< 0.001
General health	58.7 ± 11.2	68.9 ± 9.7	0.002
Vitality	45.8 ± 10.3	62.4 ± 8.9	< 0.001
Social functioning	52.3 ± 13.1	74.6 ± 10.2	< 0.001
Role-emotional	48.9 ± 14.7	69.8 ± 12.3	< 0.001
Mental health	54.2 ± 11.8	71.3 ± 9.6	< 0.001

SF-36: Short Form-36.

Based on AOFAS scores, 18 of 23 patients achieved good to excellent outcomes (AOFAS score > 80). The remaining 5 patients had fair outcomes (AOFAS score 70-79), with residual mild pain during high-impact activities, though all reported significant improvement compared to preoperative status.

Radiographic outcomes

Postoperative MRI scans were available for all 23 patients. Mean Magnetic Resonance Observation of Cartilage Repair Tissue score was 82.4 ± 9.1. Complete graft integration and fill were observed in 16 of 23 patients (70%), and substantial fill (> 75%) with good integration was seen in 4 patients (17%). In total, 20 of 23 patients (87%) demonstrated satisfactory graft healing on MRI. Three patients had incomplete graft fill, which correlated with their fair clinical outcomes.

Complications

No major complications occurred, including deep infection, nerve injury, or fixation failure. One patient (4%) experienced delayed union of the medial malleolar osteotomy, successfully managed with prolonged protected weight-bearing and healed by 6 months postoperatively. Two patients (9%) developed superficial wound infections, which resolved with oral antibiotic courses. Five patients experienced residual mild pain, though substantially improved from preoperative status. Specifically, one patient in their late 20s had residual intermittent pain with high-impact exercise. Postoperative plain radiographs for this patient demonstrated a healed medial malleolar osteotomy with stable fixation, but also revealed significant osteocartilaginous overgrowth of the allograft repair tissue projecting from the medial talar dome (Figure 7). This overgrowth was managed conservatively and did not necessitate reoperation, as the patient maintained a good functional outcome. No patients required reoperation at final follow-up.

Figure 7 Anteroposterior plain radiograph of the right ankle at 12-month follow-up for the patient with residual intermittent pain. The image demonstrates a stable osteosynthesis and a completely healed medial malleolar osteotomy site, with clear evidence of significant osteocartilaginous overgrowth of the allograft repair tissue projecting from the medial talar dome.

DISCUSSION

This case series demonstrates that treatment of symptomatic OCDs of the medial talar dome with a cartilage allograft following medial malleolar osteotomy represents a safe and effective procedure providing significant clinical and radiographic improvements at midterm follow-up. To our knowledge, this constitutes the first case series reporting outcomes of this specific technique combination for this challenging clinical problem.

The novelty of our approach lies in systematic defect bed preparation with drilling using 1.2-mm Kirschner wires, followed by bone marrow aspirate application ensuring complete saturation before allograft implantation. This methodology optimizes the biological environment for graft integration by providing mechanical stimulation through drilling and cellular enhancement through bone marrow-derived mesenchymal stem cells.

Management of medial talar dome OCDs is complicated by achieving adequate surgical exposure. While arthroscopic techniques remain preferred for many talar OCDs, lesions in the posteromedial talar dome aspect (Raikin zone 4) are frequently inaccessible to standard arthroscopic approaches[1,2]. Medial malleolar osteotomy provides excellent visualization and perpendicular lesion access, allowing thorough debridement and precise graft placement[3,4]. However, the osteotomy carries potential risks, including nonunion, malunion, and posterior tibial tendon injury[19]. In our series, we encountered one delayed union case, which healed with conservative management, and no malunion or tendon injury cases, suggesting careful surgical technique can minimize these risks.

The mean lesion size of 1.8 cm² in our series represents a critical threshold that justifies both the use of medial malleolar osteotomy for adequate surgical exposure and the application of cartilage allograft technology[13]. Large OCDs exceeding 1.5 cm² have demonstrated poor outcomes with arthroscopic bone marrow stimulation techniques, with success rates dropping significantly compared to smaller lesions[20,21]. This size criterion was a key factor in our treatment algorithm, as lesions of this magnitude require both perpendicular access for adequate debridement and sophisticated cartilage repair techniques capable of providing durable hyaline-like cartilage restoration[22]. Recent literature supports the effectiveness of various surgical approaches for talar OCDs. A comprehensive systematic review by van Diepen et al[14] analyzing 11785 patients demonstrated the importance of standardized reporting of lesion morphology, location, and size in treatment outcomes. Similarly, Walther et al[15] provided updated recommendations for operative management of talar OCDs, emphasizing the role of lesion characteristics in treatment selection. Our results align with these contemporary findings, demonstrating favorable outcomes with our systematic approach.

The cartilage allograft utilized in this study offers several potential advantages. It represents a single-stage, off-the-shelf product containing viable chondrocytes and native cartilage matrix, providing a scaffold for cartilage regeneration without requiring secondary surgery or donor site morbidity[13]. Recent advances in cartilage repair technology have shown promising results with various allograft materials, with studies demonstrating improved clinical outcomes compared to traditional techniques[23].

Fibrin glue utilization for graft fixation represents another important technical consideration. Fibrin sealant functions as a plasma-derived two-component adhesive (fibrinogen and thrombin) that polymerizes into a cross-linked fibrin clot, creating a biologic cap that stabilizes the graft, preserves its contour, and protects against early shear. While some studies have raised concerns regarding fibrin glue's potential to inhibit chondrocyte migration and proliferation[20,21], our results suggest it provides adequate initial fixation allowing graft integration, as evidenced by the high rate of satisfactory graft healing on MRI.

Our results compare favorably with other techniques for treating medial talar OCDs. Recent studies have reported mean AOFAS scores ranging from 82-89 at similar follow-up periods[22]. Our mean AOFAS score of 88.7 at 24 months follow-up suggests that the cartilage allograft may provide comparable or superior outcomes to traditional techniques.

Comparative analysis with established treatments for large medial talar OCDs requiring medial malleolar osteotomy reveals favorable outcomes with our cartilage allograft approach. Osteochondral autograft transplantation for similar-sized lesions has reported mean AOFAS scores ranging from 78-85, with donor site morbidity rates of 10%-15%[23,24]. Fresh osteochondral allograft transplantation, while showing excellent results with AOFAS scores of 85-92, is limited by tissue availability, cost, and the need for size matching[25,26]. Autologous chondrocyte implantation for large talar lesions has demonstrated AOFAS scores of 80-88, but requires a two-stage procedure with associated increased morbidity and cost[27,28]. Our single-stage cartilage allograft technique achieved a mean AOFAS score of 88.7 with 80% good to excellent outcomes, comparing favorably to these established treatments while avoiding donor site morbidity and the complexity of two-stage procedures.

This study has several important limitations that must be acknowledged. First, the retrospective case series design lacks a control group, limiting our ability to directly compare outcomes with alternative treatment modalities. Selection bias may have influenced patient inclusion, as the decision for medial malleolar osteotomy and cartilage allograft was based on surgeon preference and lesion characteristics rather than randomized allocation. The relatively small sample size of 23 patients, while adequate for a case series, limits the statistical power for subgroup analyses and rare complication detection. Non-standardized preoperative imaging protocols may have introduced variability in lesion assessment and classification. Additionally, while MRI was the primary imaging modality for its superior assessment of cartilage, we acknowledge that computed tomography scans can provide more detailed subchondral bone assessment and were not routinely used in this series. The follow-up period, while adequate for midterm assessment, remains insufficient to evaluate long-term durability of the cartilage repair tissue. Additionally, the single-surgeon experience may limit the generalizability of these results to other centers and surgeons with different experience levels. Cost-effectiveness analysis was not performed, which is an important consideration given the expense of cartilage allograft technology compared to traditional techniques.

Despite these limitations, this study provides valuable information regarding a promising treatment option for a challenging clinical problem. The combination of medial malleolar osteotomy for exposure, systematic defect preparation with drilling and bone marrow aspirate, and the cartilage allograft for cartilage repair appears to represent a safe and effective approach for treating symptomatic medial talar dome OCDs.

CONCLUSION

Treatment of symptomatic OCDs of the medial talar dome with the cartilage allograft following medial malleolar osteotomy represents a safe and effective procedure yielding significant clinical and radiographic improvements at midterm follow-up. The novel approach of systematic defect preparation with drilling and bone marrow aspirate application before allograft implantation may optimize graft integration. This single-stage procedure provides a promising therapeutic option for these challenging lesions, though long-term follow-up remains necessary to assess repair tissue durability.

ACKNOWLEDGEMENTS

The authors thank the surgical and nursing teams who assisted with patient care.