Treatment Strategies in Osteochondral Defects of the Talar Dome: a Systematic Review

Abstract

The aim of this study was to investigate the results of different treatment strategies for osteochondral defects (OCD) of the talus. Electronic databases from 1966 to July 1998 were systematically screened. Based on our inclusion criteria 32 studies describing the results of treatment strategies for OCD of the talus were included. No randomized clinical trials (RCT's) were identified. Fourteen studies described the results of excision alone, 11 the results of (EC), 14 the results of (ECD), 1 the results of cancellous bone grafting after EC, 1 the results of osteochondral transplantation and 3 the results of fixation. The average success rate of non-operative treatment (NT) was 45%. Comparison of different surgical procedures shows that the average highest success rate was reached by excision, curettage and drilling (ECD) (85%) followed by excision and curettage (EC) (78%) and excision alone (38%). Based on this systematic review we conclude that NT and excision alone are not to be recommended in treating talar OCD. Both EC and ECD have been shown to lead to a high percentage good/excellent results. However, due to great diversity in the articles and variability in treatment results, no definitive conclusions can be drawn. Further prospective randomized controlled trials are required to compare the outcome of these two surgical strategies for OCD of the talus.

INTRODUCTION

The terms osteochondritis dissecans, transchondral fracture, osteochondral fracture and osteochondral defect (OCD) are used in the literature to describe the separation of a fragment of articular cartilage, with or without subchondral bone.^1,3,26 The most common location is the knee, but it can involve any joint. This review will focus on OCD of the ankle joint, in which it predominantly affects the trochlear part of the talus.

In the eighteenth century Monro³² was the first to report the presence of cartilaginous bodies of the ankle joint. In 1888 König²⁶ defined loose bodies of the knee joint as osteochondritis dissecans and suggested that these resulted from spontaneous necrosis. Since then, several possible etiologies for these lesions have been suggested.^3,14 In the ankle, the majority of osteochondral defects is associated with previous trauma.^16,50 The currently most accepted classification (Berndt and Harty, 1959) is based on amount of displacement of the osteochondral fragment: stage I, a small area of compression of subchondral bone; stage II, a partially detached osteochondral fragment in the fragment bed; stage III, a completely detached osteochondral fragment in the fragment bed; stage IV, a displaced osteochondral fragment.

There are several types of treatment for OCD: non-operative (NT), excision of the fragment (E), excision and curettage with or without drilling (EC and ECD), cancellous bone grafting, osteochondral transplantation, or internal fixation of the fragment. In the literature different opinions exist about the best treatment for OCD.^{4,8,11,12,16,28,35,41,45–47} The suggested protocols vary from treating all lesions non-operatively⁴⁵ to treating only Berndt & Harty stage 1 non-operatively.^3,35 Other authors base their decision of treatment strategy on the size of the lesion: small lesions can be treated non-operatively, large (>1.5 cm) require surgery.³⁷ Surgical protocols vary as well. Personal preferences can be a reason to follow a certain procedure, as well as staging according to Berndt & Harty.^11,25,34,49 The last decade most surgeons perform arthroscoic intervention^{2,13,15,23,30,37,38,40,42,44,49,51,52}

New (experimental) studies focus on so-called biological repair and regeneration of cartilage, using cultured or autologous chondrocytes⁷, osteochondral grafts¹⁷, periosteal and perichondreal grafts²⁴. To evaluate the success rates of these new therapeutic methods, valid and reliable comparisons with existing non-operative and surgical strategies are necessary. To the best of our knowledge no review is available in which the existing therapeutic strategies are systematically investigated. According to the principles of “evidence based analysis in medicine” the best medical care is provided by integrating the best external evidence obtained from clinically relevant research into the daily practice. By combining relevant studies in a systematic review, the power and precision of estimates on results can be increased. The aim of this study was to summarize the available studies in order to compare the success rates of different treatment strategies for OCD of the talus.

TABLE 1

RESULTS OF TREATMENT STRATEGIES FOR OCD OF THE TALUS, EXPRESSED IN PERCENTAGE AND RATIO NUMBER OF PATIENTS WITH EXCELLENT/GOOD RESULTS VERSUS TOTAL NUMBER OF PATIENTS

TABLE 2

STUDY CHARACTERISTICS; DESCRIPTION OF TYPE OF OPERATION, MEAN AND RANGE (WITHIN BRACKETS) OF FOLLOW-UP, SEX DISTRIBUTION, POPULATION DESCRIPTION AND HISTORY OF TRAUMA SUBDIVIDED IN LATERAL AND MEDIAL FOR INCLUDED STUDIES

MATERIAL AND METHODS

Data sources

The authors have screened the electronic databases MEDLINE (from 1966 – July 1998), EMBASE (from 1988 – May 1998), CINAHL (from 1982 – March 1998) and Current Contents (till June 1998). As keywords we used “osteochondritis dissecans and treatment, cartilage, osteochondral defect, ankle, arthroscopy, transchondral defect, transchondral fractures, talar dome fractures, review, meta-analysis and randomized clinical trial”. No limitation was made regarding language. Of the articles selected, the reference lists were searched for additional articles.

Study Selection: Inclusion and exclusion criteria.

Two investigators independently assessed the articles for inclusion. Agreement was needed for inclusion. In case of disagreement, the opinion of a third independent investigator was decisive. To prevent investigator bias, scoring of the manuscripts was blinded to author and institute. Included were studies describing the results of the following treatment strategies: non-operative (NT), excision of the fragment, excision + curettage (EC), excision + curettage + drilling (ECD), cancellous bone grafting subsequent to EC, osteochondral transplantation and fixation. Studies were included if there was a proper description of the treatment for OCD of the talus and a well defined outcome. Patients were excluded if the duration of follow-up was less than 6 months, if patients had received an improperly described therapy or combination of therapies, if their age was under 18 or if they were described in a single case-report. In case of double publications only the most elaborate publication was selected.

Data Extraction

Successful treatment was defined as an excellent or good result at follow-up. If success rate was not labeled by the author, the results were fitted into the widely accepted score of Thompson and Loomer (1984).⁴⁸ The proportion of the patient population with successful treatment was noted and percentages were calculated. (Table I) For each treatment strategy, study size weighted success rates were calculated.

RESULTS

Description of studies

A total of 107 publications describing the results of treatment of talar OCD could be identified. Seventy-five studies had to be excluded due to inappropriate duration of follow-up (n=1), improper description or combination of therapies (n=33), age under 18 (n=2), non-interpretable results (n=28), case report (n=9) and double publication (n=2). No randomized clinical trials were found. Therefore the conventional measures of summarizing estimates of effectiveness could not be used. We used pooling of the estimates of the outcome in individual studies.

Of the 32 selected studies, 14 described the results of “non-operative treatment”^{5,11,14,16,19,20,25,31,33,39,40,43,48,53}, 4 the results of excision alone^3,14,36,39, 11 the results of EC^{2,3,5,11,15,25,29,30,37,38,40}, 14 the results of ECD^{1,9,13,14,16,20,23,31,34,36,44,48,49,52}, one the results of usage of cancellous bone grafting after EC⁹, one the results of osteochondral transplantation²¹ and 3 the results of fixation. (Table 1)^1,18,39 (Often, more than one treatment method was included in an article)

Population characteristics

The total number of patients with OCD of the talus in the 32 included studies was 701. Of these 701 patients, 582 were included in this systematic review based on our criteria.

Average and range of follow-up for each study are presented in Table II. The average age was 27 years and 67% were male and 33% female. (Table II) Seventy eight percent of the patients were civilian and 22% military. Forty-four percent talar dome lesions were lateral and 56% were medial. A history of ankle trauma was reported in 76% of patients. Lateral talar dome lesions were associated with previous ankle trauma in 94%. For medial dome lesions this figure was 62%.

Therapies Non-operative Treatment (NT)

The definition of NT of talar OCD's varied in the different publications. A subdivision could be made in 2 categories: (A) rest/restriction of (sport-) activities with or without use of non-steroidal anti-inflammatory drugs (NSAID), or (B) cast immobilization for 3 weeks to 4 months. (Table III) The considerations for treating patients non-operatively were: minor complaints²⁰, radiological Berndt and Harty stage I and II^3,25 medial stage III lesions¹¹ or intact cartilage as determined by arthroscopy.⁴⁰ The remaining publications did not give an exact description of the indication for NT.^{5,14,16,19,31,33,39,40,43,48,53} Fourteen studies, with a total of 201 patients, describe the results of NT for OCD. in 91 of the 201 patients (45%) treatment was reported to be successful.^{3,5,11,14,16,19,20,25,31,33,39,40,43,48,53}

In the majority of studies the duration of symptoms prior to institution of NT was either unreported or ranged from sub-acute (>6 weeks) to chronic (<6 weeks). Only in one study were the results of acute lesions alone described.¹⁶ Of 6 patients with acute lesions, treated by 4–6 weeks non-weightbearing immobilization followed by progressive weightbearing for 2–8 weeks, no good or excellent results were reported. The outcome of NT in solely chronic lesions (>6 weeks) was described in three studies.^19,40,48 All chronic lesions were treated by rest or restriction of (sports-) activities. The average success rate in the 3 studies was 56%.^5,9

The results of 17 patients treated by rest or restriction of activities were described in 7 studies.^{14,19,20,31,40,48} The success rate of this type of treatment was 59%. Immobilization for at least 3 weeks up to 4 months in 131 patients resulted in 41% good/excellent results.^{5,11,14,16,19,20,25,31,39}

Surgical Treatment

Until the mid-eighties surgical treatment of talar OCD's consisted of open procedures. In case of posteromedially located OCD's most surgeons performed an osteotomy of the medial malleolus, to identify and treat the lesion.^18,20,34 The introduction of arthroscopy has led to less invasive operative procedures.

The consideration for treating patients surgically was failure of NT^{1–3,6,9,13,16,30,31,37,38,49} or presence of more advanced lesions: acute or chronic radiographic Berndt & Harty stage II-IV lesions³⁴, acute^11,25 or chronic²⁵ stage III and IV lesions. Pritsch⁴⁰ based the surgical indication on arthroscopic appearance of a frayed cartilage lesion. Surgical treatment options are excision, EC, ECD, cancellous bone grafting, osteochondral transplantation or internal fixation.

TABLE 3

RESULTS OF CONSERVATIVE TREATMENT SUBDIVIDED IN TREATMENT TYPE, INDICATION, DURATION OF TREATMENT, ACUTE OR CHRONIC LESIONS

Excision

With this technique the separated fragment is excised. A total of 4 studies, (39 patients), reported the results of open surgical treatment of OCD by excision alone,^3,14,36,39 In 15 of the 39 patients (38%) the treatment was reported to be successful. The success rate in the 4 studies varied from 30–100%.

Excision and Curettage (EC)

With this technique the loose body is excised and surrounding (subchondral) necrotic tissue is curetted either through open or arthroscopic technique. Eleven studies, (141 patients), reported on the results of OCD treatment by EC.^{2,3,5,11,15,25,29,30,37,38,40} In 110 of the 141 patients (78%) treatment was successful. The success rate varied from 53%–100%. The success rates for open procedures and arthroscopy were 63% (31/49) and 86% (79/92) respectively.

Excision, Curettage and Drilling (ECD)

With this technique, following excision and curettage, holes are drilled in the subchondral bone to enhance vascularization and hopefully stimulating the repair process. After simple excision, the remaining cartilage has less potential to heal. By perforating the sclerotic subchondral bone zone into the vascularized subchondral bone, neo-vascularity of the defect is hopefully induced. Two studies were selected because they gave an accurate description of the items necessary for classification.^19,43

No uniform definition for the outcome of treatment was used. Because of this, no differentiation could be made regarding severity of the disease and size of the defect. This may bias the comparison between studies. Comparison of different surgical procedures within studies shows that the outcome of ECD is superior to excision alone.^14,36 No data are available to compare ECD with EC in the same study. The superior results of ECD compared to excision alone are consistent with the description of the overall results. Unfortunately no data were available to confirm within a given study the reported difference between ECD and EC. Therefore, still no evidence is available to verify the difference in outcome of these two types of surgical intervention.

No uniform evaluation according to a radiological classification has been used. Only six authors base their decision for a specific treatment on staging according to Berndt & Harty.^{2,3,11,25,34,40} Therefore it was not useful to describe the results according to radiological staging in a seperate section. The value of preoperative roentenographic staging seems to be of minor value, since it correlates inclusively with the intraoperative findings.⁴⁰ The lack of correlation between the radiographic and arthroscopic appearance of the lesions demonstrates its shortcoming as a guide for the treatment strategy. An intraoperative staging of the defect would be appropriate.^49,40 Between and within studies there were great differences in type and duration of NT with a wide range (0–100%) of reported success rates. It varies from no treatment³¹ to plaster cast immobilization for 4 months.¹⁴ We subdivided the NT's in 2 categories: (A) rest or restriction of (sports-) activities (17 patients), or (B) immobilization for at least 3 weeks up to 4 months (131 patients). The success rates were 59% and 41% respectively. (Table I) These figures are too low to recommend NT.

A substantial part of surgically treated lesions were resistant to NT^{1,3,13,16,30,31,37,38,49} These failures of NT are not recorded in the overall low success rate of NT. Taken this into account, the moderate success rate of NT would be overestimated.

The calculated overall success rate of surgical intervention (75%) is comparable with the percentage from the review of the literature until 1983.¹⁶ This percentage, however, is achieved by several completely different surgical techniques with different success rates. For the individual surgeon the practical value of the average success rate of surgical intervention is therefore limited in choosing for a specific surgical method. We have subdivided the surgical techniques to analyze the success rates of the different techniques. The systematic subdivision shows that ECD is associated with a high percentage of good/excellent results (88%).

In the future clinical trials focussing on biological repair and regeneration can be expected. These new techniques using cultured or autologous chondrocytes⁷, osteochondral grafts¹⁷, cartilage transplantation^21,22, periosteal and perichondreal grafts 24 should address their value in treatment of OCD of the talus.

SUMMARY

This systematic review emphasizes the variability in treatment results for the different types of OCD. No randomized clinical trials were found on the subject. Also there is great diversity of pre- and postoperative classifications in the articles included. This lack of consistency influences interpretation of the information. Therefore no definitive conclusions can be drawn. Prospective randomized controlled trials with standardized pre- and postoperative classifications are required to compare the outcome of these two surgical strategies. Still, this review is useful in providing a complete overview of the literature on this subject.

Low success rates have been reported for NT and excision. Both EC and ECD have been shown to lead to a higher percentage good/excellent results.

The results of cancellous bone grafting, osteochondral transplantation and fixation are encouraging. However, as of yet, too few qualitative studies on patients with these techniques are available to draw any firm conclusions.

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