Abstract
Dear Editor
We read with interest the paper by Tsiouri et al. [1]. The authors presented their experience of the use of the Tightrope implant for the stabilization of acute and chronic acromioclavicular joint dislocations and lateral clavicle fractures in 40 patients. They reported a ‘disappointingly’ high rate of failure of 19% (nine patients) and, as a result, the authors concluded that the Tightrope alone is not adequate to stabilize the acromioclavicluar joint.
In their conclusion, the authors stated that they were unable to identify any specific factor that contributed to failure and therefore have ceased using the Tightrope implant. We considered that it was important to highlight several factors that, in our opinion, significantly contributed to the failure rate presented in this series.
The original description of the technique [2], [3] advised on the use of the procedure for acute injuries defined as dislocations sustained less than 4 weeks before the operation. The procedure is not advised for use in cases of chronic dislocation and, in our institution, we use a Modified Weaver–Dunn procedure (i.e. a biological reconstruction of the coracoclavicular ligaments) for such cases. The authors have chosen to ignore this advice. First, their cut off for defining an injury as acute is 6 weeks rather than 4 weeks. This would imply that a significant (but unspecified in their paper) number of patients underwent surgery between 4 weeks and 6 weeks post injury. Second, the authors have chosen to treat 13 chronic cases with a mean time to surgery of 13 weeks. The authors have therefore reported an extremely small series of patients treated appropriately: at most, this numbers 18 in total but, in reality, because several ‘acute’ patients are likely to have had operations after the 4-week window, the number of appropriately treated patients is likely to be much less than this. Four of the nine failures occurred in patients with chronic injuries. It is not possible to determine from the data presented in their paper how many of the remaining five failures occurred when operations took place more than 4 weeks after the injuries.
One of the five failures in the acute group was attributed to infection. To our knowledge, infection is not the exclusive domain of this technique.
Two of the five failures in the acute group were stable asymptomatic subluxations. It has also been our experience that such radiological subluxations are minor, of no cosmetic concern, entirely asymptomatic and nonprogressive. We do not consider such cases as failures of the technique.
The remaining two of the five failures in the acute group failed by ‘cutting out’. Cut out usually results from an error with the positioning of the drill hole: the drill hole is either placed too anteriorly or posteriorly in the clavicle or too medially or laterally in the coracoid and this leaves a thin cortical shell through which the implant can cut out. In our series of 50 cases [3], all failures bar one were the result of a technical error. Failure as a result of technical error is probably more likely with the use of two separate drill holes
There are other concerns with their paper. Although the authors wrote ‘Postoperative immobilization was limited to 4 weeks in a sling’, they pointed out in their results section that there was a significant rate of noncompliance, with an average of only 3 weeks in a sling after the operation and as little as 0 weeks! This also questions the compliance with return to physical activity and sport. The failure rate reported by Bain et al. [4] arose as a result of allowing patients to return to physical activity immediately after surgery and therefore cannot be considered as a failure of technique but of rehabilitation. The authors did not indicate how many of their failures complied with postoperative rehabilitation instructions and it is not certain how many of their patients fall into the category of failure of rehabilitation rather than failure of technique.
Another concern is the statistical analysis used to identify relationships between failure and factors such as type of injury, chronicity, use of single or double Tightrope, etc. The number of patients in their series is extremely small and this makes the risk of a type II error (i.e. failure to reject the null hypothesis when there really is a difference) very high and the statement that they found no significant correlation unreliable.
Finally, we have concerns about the attention to detail in their paper. The name of the author of the original description of the technique is spelled incorrectly in two of the three references in their paper.
We can conclude from the data presented that, of 31 cases presented in their paper, 13 chronic cases were treated contrary to the recommendation in the description of the original technique. Of the remaining 18, an unspecified number were treated outside the recommended 4-week window and an unspecified number were not compliant with their rehabilitation. Two of these 18 patients (11%) failed as a result of a technical error, which may have been made more likely by the authors’ use of a double drill hole and double implant technique.
Given the authors’ choice to disregard important recommendations made in the original description of the technique, we think it wise that they no longer use the technique. However, we would suggest that their paper is not representative of the results when the manufacturer's advice is followed by a skilled arthroscopist.