Autologous Costal Cartilage Transplantation for Medial Osteochondral Lesions of the Talus

Abstract

Background:

Osteochondral lesions of the talus (OLT) are common and clinically challenging conditions with no consensus on how to optimally treat them. This prospective single-arm study aimed to evaluate the clinical outcomes of autologous costal cartilage transplantation (ACCT) for OLT.

Methods:

A prospective single-arm study of patients who were diagnosed with medial OLT and underwent ACCT with 2 years of follow-up was performed. There were 28 patients enrolled at a single center. The primary outcome was changes in American Orthopaedic Foot and Ankle Society (AOFAS) scores from baseline. The secondary outcomes included results of the EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) for quality of life, the visual analog scale for pain, the Tegner score for sports activity, and magnetic resonance observation of cartilage repair tissue (MOCART) scoring system for imaging evaluations.

Results:

All 28 enrolled patients (41.82 ± 11.98 years, 9 female and 19 male) completed the initial study and the 2 years of follow-up. The AOFAS score improved significantly from 58.89 ± 8.74 preoperatively to 86.5 ± 7.41 at 1 year and 90.53 ± 5.49 at 2 years (p < 0.01 for both). EQ-5D-5L index improved from 0.866 ± 0.042 at baseline to 0.976 ± 0.041 at 2 years postoperatively (p < 0.01). Tegner score increased by 1.96 ± 0.69 at 2 years (p < 0.01). Patients reported significant pain relief at 2 years postoperatively (VAS: from 3.89 ± 0.87 to 0.75 ± 0.58, p < 0.01; EQ VAS: from 63.75 ± 6.02 to 88.57 ± 6.21, p < 0.01). The mean MOCART scores were 81.07 ± 11.25 at 6 months, 83.57 ± 11.85 at 1 year, and 82.32 ± 10.92 at 2 years. Complete filling of the defect was observed in all 28 patients at 2 years, and complete integration of the graft with the bone was seen in 25 cases (89.29%).

Conclusions:

ACCT for OLT led to significant improvement in clinical outcomes and effectively repaired talar osteochondral lesions, with grafts maintaining stability and integrating well with the host tissue over time. This study introduces ACCT as a novel strategy for OLT.

Level of evidence:

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Introduction

Up to 70% of sprains and fractures involving the ankle are thought to result in osteochondral lesions of the talus (OLT)¹. OLT presents a significant clinical challenge because untreated OLT can lead to the development of osteoarthritis, which may result in chronic pain, functional impairment, and reduced quality of life².

OLT is usually treated surgically, as the results of nonoperative treatment have shown a success rate of less than 50%³. Microfracture is the main surgical treatment especially for patients with small defects and aims at inducing the formation of fibrocartilage⁴. However, the functionality regained after microfracture deteriorates over time because fibrocartilage is weaker than hyaline cartilage. Thus, many alternative treatment techniques aim to achieve a hyaline-like repair, such as autologous chondrocyte implantation (ACI) and osteochondral autograft transplantation (OAT)⁵. However, ACI requires 2-stage surgery, and tissue repaired by ACI are mechanically weak^6,7. As for OAT, osteochondral autograft materials are usually harvested from the healthy knee joint, which increase the risk of the donor site morbidity. In addition, the bone tissue inside osteochondral autograft is difficult to cut and shape^8,9. Thus, current surgical procedures are inadequate to meet therapeutic demands of OLT, highlighting the necessity to explore new surgical options.

The ideal graft used to repair OLT should possess structure and biological properties similar to the original articular cartilage. Costal cartilage is the most abundant source of hyaline cartilage in the human body and is accessible with minimal injury¹⁰. Free costal cartilage is easily moldable and has been used in plastic surgery for non–weight-bearing portions of the body, including rhinoplasty¹¹ and auricular reconstruction¹². A previous study used autologous costal cartilage transplantation (ACCT) to repair osteochondral lesions on the femoral head¹⁰, and the results indicated the potential of ACCT in applications related to weight-bearing joints. Therefore, this study aimed to evaluate the efficiency and safety of free ACCT in treating OLT.

Materials and Methods

Study Design

This was a prospective single-arm study with 2 years of follow-up. The protocol was approved by the Human Ethics Committee of Shanghai Sixth People’s Hospital Affiliated with the Shanghai Jiao Tong University School of Medicine, in the People’s Republic of China (Approval No. 2020-118) and was registered in the Chinese Clinical Trial Registry (ChiCTR2000035736).

Patients with medial OLT were recruited at a single center. The inclusion criteria were: (1) medial OLT diagnosis confirmed through computed tomography (CT) and magnetic resonance imaging (MRI); (2) participants aged between 16 and 65 years; (3) symptoms that persisted for a minimum of 3 months, limiting daily activities; (4) patients those agree to undergo ACCT and could provide informed consent; and (5) individuals with a complete medical history and are willing to conduct follow-up at our medical center. The exclusion criteria were: (1) an affected ankle joint showing signs of rheumatoid arthritis; (2) the presence of congenital or acquired malformations in the affected ankle joint; (3) an ankle joint fracture on the same side; (4) rib fractures or deformities; and (5) a current active chest infection.

Surgical Procedure

Figure 1A summarizes the surgical procedure. This procedure included following steps: medial malleolar Chevron osteotomy and exposure of lesions (Fig. 1B), debridement of damaged cartilage and necrotic tissue (Fig. 1C), harvesting of costal cartilage (Fig. 1D), preparation (Fig. 1E) and fixation (Fig. 1F) of the graft, graft congruency adjustment (Fig. 1G), as well as stabilization of the medial malleolar fragment. The detailed postoperative rehabilitation protocol is provided in the Supplementary Materials.

Fig. 1.

The surgical procedure of autologous costal cartilage transplantation for the treatment of talar cartilage lesion. (A) Illustration of surgical procedure. (B) An incision approximately 5 to 7 cm in length was performed over the medial malleolus. After the medial malleolar Chevron osteotomy, osteotomized medial malleolus was retracted inferiorly to achieve the required exposure of the medial osteochondral lesions of the talus. (C) Using bone knives and bone curettes to debride the damaged cartilage, necrotic, and devitalized tissue, as well as sclerotic bone, down to fresh bleeding bone bed. (D) A 2-3-cm transverse incision was made along the chondral portion of the sixth rib on the right side. After dissecting the attached muscle bluntly, a 2-cm segment of the costal cartilage was harvested. (E) Costal cartilage graft (white arrow) was trimmed and press-fit to the osteochondral defect on the talus. (F) The graft was fixed using an absorbable pin (2 mm in diameter; FreedomPin™; Inion) (yellow arrow). (G) Additional trimming was performed to match the congruency of the peripheral articular surface of the talus. Following reduction of the medial malleolar fragment, 2 or 3 cannulated screws were inserted for stabilization.

Patient-Reported Outcomes

Clinical outcomes were assessed preoperatively, 6 months, 1 year, and 2 years after surgery. The primary outcome was improvements in the American Orthopaedic Foot and Ankle Society (AOFAS) score for ankle function¹³. Clinical outcomes at follow-up were graded as excellent (90-100 points), good (80-89), fair (70-79), or poor (<70) based on AOFAS scores¹⁴. The secondary outcomes were comprised of other patient-reported results, including EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) for quality of life¹⁵, visual analog scale (VAS) scores for pain¹⁶, and Tegner scores for sports activity¹⁷. Minimal clinically important difference (MCID) for scoring systems above were also evaluated.

Imaging Outcomes

Radiographic assessment was conducted at baseline and postoperatively at 6 months, 1 year, and 2 years using CT and MRI. Lesion size, morphology, location (9-grid scheme)¹⁸, and ankle OA grade (International Cartilage Repair Society classification)¹⁹ were assessed. Magnetic resonance observation of cartilage repair tissue (MOCART) (0-100 points) scores²⁰ at 6 months, 1 year, and 2 years postoperatively were used to assess the quality of the repair cartilage and the subchondral bone.

Statistical Analysis

A paired t test or the Wilcoxon signed-rank test was used to compare AOFAS, VAS, EQ-5D-5L, Tegner, MOCART scores between baseline and postoperative assessments. The strength of associations between demographic, MRI findings, and postoperative ankle function was indicated by Spearman rank correlations. All reported p-values are 2-sided, and a p-value of < 0.05 was considered significant. All analyses were performed in R (version 4.1.3; Lucent Technologies; NJ, USA).

Results

There were 37 patients with progressive ankle pain that were screened. Out of these, 28 met the inclusion criteria and were enrolled in the study. All 28 patients subsequently completed the 2-year follow-up. The baseline characteristics of patients are presented in Table I and Supplementary Table S1.

Table I.

Baseline Characteristics of the Patients

Characteristic	Costal Cartilage Transplantation (N = 28)
Age at surgery, years, range and mean ± SD	18-62, 41.82 ± 11.98
Sex, female, n (%)	9 (32.14)
Body mass index, kg/m2, Mean ± SD	26.61 ± 2.74
Duration of symptoms, months, Mean ± SD	29.05 ± 29.93
Symptomatic ankle, n (%)
Right ankle	17 (39.29)
Left ankle	11 (60.71)
Both ankle	0 (0)
Baseline measures, Mean ± SD
AOFAS	58.89 ± 8.75
VAS	3.89 ± 0.87
EQ-5D-5L Index	0.866 ± 0.042
EQ-VAS	63.75 ± 6.02
Tegner	2.82 ± 0.67
ICRS grade IV, n (%)	28 (100)
Lesion size, cm2, Mean ± SD	1.57 ± 0.78
Lesion depth, cm, Mean ± SD	0.89 ± 0.27
Lesion location, n (%)
Zone 1	6 (21.43)
Zone 4	18 (64.29)
Zone 7	4 (14.29)

AOFAS = American Orthopaedic Foot and Ankle Society; EQ-5D-5L = EuroQol 5-dimension 5-level questionnaire, ICRS = International Cartilage Repair Society classification, and VAS = visual analog scale; SD, standard deviation.

In the 2 years of follow-up, there were no cases of revision surgery for failed ACCT. No severe donor site morbidities, including pneumothorax, intercostal nerve injury, infection, and rib fracture were observed. AOFAS scores improved significantly from 58.89 ± 8.74 preoperatively to 86.5 ± 7.41 at 1 year and 90.53 ± 5.49 at 2 years (p < 0.01 for both) (Table II). Twenty-seven patients (96.43%) achieved excellent or good level of ankle function at 2 years. EQ-5D-5L index improved from 0.866 ± 0.042 preoperatively to 0.970 ± 0.043 at 1 year and 0.976 ± 0.041 at 2 years after surgery (both p < 0.01) (Table II). Tegner score increased by 1.92 ± 0.81 at 1 year and 1.96 ± 0.69 at 2 years. For pain reduction, EQ-VAS improved from 63.75 ± 6.02 preoperatively to 86.25 ± 6.18 at 1 year and 88.57 ± 6.21 at 2 years (both p < 0.01), and VAS decreased from 3.89 ± 0.87 preoperatively to 1.03 ± 0.63 at 1 year and 0.75 ± 0.58 at 2 years (both p < 0.01). Patient age, lesion size, and postoperative MOCART scores did not correlate with AOFAS score, while higher body mass index (BMIs) tended to result in poorer AOFAS scores (p = 0.009) (Supplementary Table S2). MCIDs for scoring systems in ACCT surgery are summarized in Supplementary Table S3.

Table II.

Patient-Reported Clinical Outcomes

	Baseline	6 Months	1 Year	2 Years
AOFAS-total	58.89 ± 8.74	77.78 ± 8.89**	86.5 ± 7.41**	90.53 ± 5.49**
AOFAS-pain	23.93 ± 4.97	29.28 ± 5.39**	34.29 ± 5.04**	36.07 ± 4.97**
AOFAS-function	29.25 ± 6.73	42.79 ± 5.98**	46.32 ± 4.04**	48.21 ± 2.42**
AOFAS-alignment	5.71 ± 1.78	5.71 ± 1.78	5.89 ± 1.95	6.1425 ± 2.20
EQ-5D-5L Index	0.866 ± 0.042	0.933 ± 0.024**	0.970 ± 0.043**	0.976 ± 0.041**
EQ-VAS	63.75 ± 6.02	80.71 ± 7.42**	86.25 ± 6.18**	88.57 ± 6.21**
VAS	3.89 ± 0.87	1.53 ± 0.74**	1.03 ± 0.63**	0.75 ± 0.58**
Tegner	2.82 ± 0.67	4.39 ± 0.74**	4.75 ± 0.52**	4.78 ± 0.42**

AOFAS = American Orthopaedic Foot and Ankle Society, EQ-5D-5L = EuroQol 5-dimension 5-level questionnaire, and VAS = visual analogue scale.

Level of significance: *p < 0.05; **p < 0.01.

The postoperative assessments (Figs. 2-E through 2-P) at 1 and 2 years demonstrated complete defect filling and robust tissue integration compared with preoperative imaging (Figs. 2-A through 2-D), and the signals were nearly identical to those of native cartilage. Arthroscopy revealed a smooth, continuous surface over the repair site, with tissue appearing firm and stable. The repaired surface was continuous with the adjacent cartilage and showed solid integration into the underlying subchondral bone (Fig. 2Q). The mean MOCART scores were 81.07 ± 11.25 at 6 months, 83.57 ± 11.85 at 1 year, and 82.32 ± 10.92 at 2 years (Fig. 2R). Complete filling of the defect was observed in all 28 patients at 2 years, and this subcategory of MOCART scores improved significantly from 16.78 ± 2.44 at 6 months to 17.86 ± 2.52 at 2 years (p < 0.01) (Supplementary Table S4). Complete integration with border zone increased significantly from 7 ankles (25%) at 6 months to 25 ankles (89.29%) at 2 years (p < 0.01).

Fig. 2.

Evaluations of Imaging outcomes. A 49-year-old man who were diagnosed with OLT and underwent free ACCT. The MOCART score was 75 at 6 months, 80 at 1 year, and 80 at 2 years. The ICRS score was 9 under second-look arthroscopy. (A-D) Preoperative coronal and sagittal planes of CT and MRI. (E-H) Coronal and sagittal planes of CT and MRI at 6 months after surgery. (I-L) Coronal and sagittal planes of CT and MRI at 1 year after surgery. (M-P) Coronal and sagittal planes of CT and MRI at 2 years after surgery. (Q) Arthroscopy at 2 years after surgery (red arrow, the ACCT graft). (R) Mean MOCART scores of 28 patients at different follow-up. Results were presented as mean (bars) and 95% CI (error bars). ACCT = autologous costal cartilage transplantation, ICRS = International Cartilage Repair Society classification, and MOCART = magnetic resonance observation of cartilage repair tissue.

Discussion

This study evaluated the clinical efficacy of ACCT in treating medial OLT, and our findings demonstrated significant improvements in patient-reported outcomes. In addition, postoperative imaging evaluations demonstrated that the implanted costal cartilage integrated with the bone bed and produced signals similar to the adjacent intact articular cartilage.

Microfracture is still the major approach to treating OLT due to its minimal invasiveness; however, it is only advantageous for small lesions less than 1 cm² in area, under 10 mm in diameter, and less than 5 mm in depth^21,22. In our case series (Table I), the average lesion area was 2.15 ± 1.32 cm², 23 patients (82.14%) had a lesion area greater than 1 cm², and all patients had lesion depths exceeding 5 mm. ACI and OAT are used for OLT treatment aiming at a hyaline-like repair^2,23. Unlike free ACCT, ACI necessitates 2 surgical procedures along with a cell cultivation phase, leading to longer hospital stays and a higher financial burden for patients^7,24. Because autologous chondrocytes lack initial stability, a chondrocyte-loaded scaffold is often required for support²⁵, while defects reconstructed using ACCT in this study showed a robust and smooth articular surface immediately after transplantation (Fig. 1G). In addition, even with ideal histological and mechanical properties, harvesting osteochondral cylindrical grafts in OAT will typically unavoidably damage the articular surface in a healthy knee joint^9,26. In this study, all the patients treated by ACCT showed no donor site problems.

The osteochondral junction portion of the ribs has recently been employed as graft material for treating OLT²⁷. However, the previous study only included 5 patients with a short 1-year follow-up. In addition, the cross-sectional area of the costal osteochondral junction is very small, which limits the size of the area to be repaired. The costal junction graft is also hard to cut according to the contour of the defect due to the bone portion. By contrast, free costal cartilage without a bony portion is easy to cut and can be harvested much more safely because of its distance from the pleura. Free costal cartilage grafts can be transplanted transversely instead of vertically, so they can fit into a much larger defect area. This study was the first prospective clinical trial to investigate the effectiveness of free ACCT for treating OLT. Our results showed that the mean AOFAS of the patients treated by ACCT improved significantly from 55.81 ± 6.72 at baseline to 90.53 ± 5.49 after 2 years of follow-up in this study, which is similar or even superior than the outcomes of OLT treated by ACI^28,29 or OAT³⁰.

In this study, postoperative CT and MRI demonstrated that grafts integrated well with the subchondral bone, showing no deterioration and maintaining their shape. These observations are consistent with the findings in our previous animal studies and a clinical trial on hip joints^10,31,32. Free ACCT achieved a mean MOCART score of 83.57 ± 11.85 at 1 year, and 82.32 ± 10.92 at 2 years. Previous radiological results after ACI for osteochondral talar lesions have been only moderate, as revealed by mean MOCART scores up to 73.71 points^27,33,34, which were significantly poorer than our results. This may be attributed to lack of initial stability and challenges in achieving complete filling of the defect associated with the ACI technique. Several studies^27,35,36 used OAT to treat OLT, with mean MOCART scores ranging from 78 to 85.8 points, which are comparable with our results.

An elevated BMI is a risk factor for poor outcomes in all cartilage repair procedures of joints^37-39. In this study, we found that elevated BMI values negatively affected clinical outcomes (Supplementary Table S2). Although lesion size is not related to postoperative ankle function (p > 0.05), it is still essential to consider the size of lesions when applying ACCT. For large lesions (lesion area >2 cm², depth >1 cm), costal cartilage grafts can adequately cover the defect because the size of the grafts can be adjusted based on the harvesting site. For small defects, considering the need to fix the graft with an absorbable pin that has a diameter of 2 mm, the short diameter of the defect should be greater than 5 mm; otherwise, the graft may fracture during fixation.

This study had several limitations. First, it had a small sample size and was performed in a single center. Although the results are promising, they might not fully represent broader population of patients with OLT. Second, the lack of a comparative treatment group restricts the ability to draw definitive conclusions about the superiority of ACCT over other surgical techniques. In addition, given that ACCT implantation is an invasive procedure, performing sham surgery as a control would have been unethical. Thus, we chose to perform an exploratory single-arm study with a small sample size that would be sufficient to obtain preliminary evidence of ACCT. Furthermore, a 2-year follow-up is not long enough, and a future study with longer follow-up and more participants is warranted.

Conclusions

This study shows that ACCT for OLT leads to a significant improvement in clinical outcomes after a follow-up of 2 years. ACCT effectively repaired talar cartilage defects, with grafts maintaining stability and integrating well with host tissue over time. The formation of a continuous osteochondral interface and remodeling of the grafted bone highlights the potential of this novel approach for treating OLT.

Ethical Review Committee Statement

This study was approved by the institutional review board of the Shanghai Sixth People’s Hospital (Approval No. 2020-118), and informed consents were obtained from all participants.

Appendix

Supporting material provided by the authors is posted with the online version of this article as a data supplement at jbjs.org (http://links.lww.com/JBJSOA/B146). This content was not copyedited or verified by JBJS.