SLR - April 2015 - Michael L. Sganga

Comparison of Clinical Outcomes Between Arthroscopic Subchondral Drilling and Microfracture for Osteochondral Lesions of the Talus

Reference: Choi JI, Lee KB. Comparison of Clinical Outcomes Between Arthroscopic Subchondral Drilling and Microfracture for Osteochondral Lesions of the Talus. Knee Surg Sports Traumatol Arthrosc. 2015 Feb 4

Scientific Literature Review

Reviewed By: Michael L. Sganga, DPM
Residency Program: Mount Auburn Hospital, Cambridge, MA

Podiatric Relevance: Osteochondral lesions of the talus (OLT) are a commonly encountered issue in foot and ankle surgery. This condition can result in pain, limited ability to perform ADLs, and inability to work. Current treatments range from core drilling, debridement, curettage, abrasion, microfracture, and osteochondral grafting. Cartilage has a poor healing capacity and non-surgical techniques for OLTs produce successful results in only 45 percent of patients. The goals of treatment are pain relief, improved function, and prevention of arthritic progression. There is no consensus in the literature on how to treat small to medium (<2cm2) OLTs and what method is most efficacious. This article proposed that subchondral drilling would not be inferior to microfracture with regard to clinical and radiographic outcomes when treating small to medium OLTs.

Methods: A total of 146 patients (150 ankles) with symptomatic OLT that underwent arthroscopic subchondral drilling or microfracture between October 2005 and June 2011. These patients were retrospectively identified and comparative study was performed. To be included ankles must have symptomatic OLT with a single focal lesion, lesion are <2cm2, age ≤60 or ≥18years, primary surgery, and failed conservative care. A total of 46 ankles on 42 patients were excluded for the following: global lesions, lesions <2cm2, aged >60 or <18 years, prior ankle fractures, and bilateral lesions. The remaining 104 ankles with isolated OLT were age and sex matched and a total of 90 ankles were enrolled in the study. These were further divided into two groups: a subchondral drilling group consisting of 40 ankles, and a microfracture group consisting of 50 ankles. The techniques were by standard means and are well described in the surgical techniques section of the article.

Pre-operative evaluation was made with clinical exam, plain film radiographs, and MRI to isolate lesions and meet inclusion criteria. Post-operative films were evaluated at three, six, 12 months, and then annually after that. Independent observers, who were blinded to exclude potential bias, evaluated the imaging studies. OLT was assessed using the standard Berndt and Hardy classification, MRI findings classified using Anderson et al staging, and arthroscopic findings were evaluated using the Ferkel and Cheng classification system.  

The outcomes were evaluated using the AOFAS ankle-hindfoot scores, visual analog scale (VAS) for pain, and a 10-point ankle activity score (AAS) scale from the Tegner scoring system to assess activity level.  The results were obtained pre-operatively and at each follow-up at three, six, 12 months, and annually thereafter.

Results: Analyzing the clinical outcomes of the procedures using pre and post-operative AOFAS, VAS, and AAS scores there were no statistically significant results. The AOFAS scores improved similarly in both the drilling and microfracture groups. The overall AOFAS results for the drilling group were excellent in 30 patients (75 percent), good in five (12.5 percent), and fair in five (12.5 percent). While the AOFAS scores in the microfracture group were excellent in 34 (68 percent), good in 10 (20 percent), and fair in six (12 percent). Additionally, VAS and AAS scores showed significant clinical improvement between pre and post-operative numbers. Overall, no statistically significant differences were seen between the two groups. 

Additional dichotomization was performed for all patients for age (<30 or ≥30 years), sex, BMI (<25 or ≥25 kg/m2), symptom duration ((<1 or ≥1 year), and lesion size (<1 or ≥1 cm2).  A multivariate analysis was then performed, however no significance was noted among the variables. There were also no reported complications with the surgical interventions in either group.  

Radiographic analysis utilizing the Berndt and Hardy classification pre-operatively, at three, six, 12 months, and final follow-up did not show any significant difference between the procedures. With regard to the arthroscopic findings, there was significant difference observed between the groups.  

Conclusions: This is the first study to compare clinical outcomes between subchondral drilling and microfracture for OLT.  By incorporating age- and sex-matched controls roughly 87.5 percent of the drilling group and 88 percent of the microfracture group achieved excellent or good results according to the AOFAS scores. The study showed that both methods present similar clinical outcomes when treating a small to medium sized OLT (<2cm2).  The authors conclude that arthroscopic subchondral drilling, and microfracture technique for stimulation of bone marrow in the treatment of OLT both provide effective and reliable results. They suggest that the surgeon can choose between either method based on preference and lesion location.

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