Dynamic external fixators for the proximal interphalangeal joint injuries: detailed biomechanical analysis of effectiveness

Backgrounds: Proximal interphalangeal (PIP) joint injuries can cause scar contractures by different mechanisms, leading to significant functional loss, the most important thing in the treatment process is to maintain joint mobility, in this way, scar formation will be reduced. Dynamic external fixators have been used for this purpose. Although it is an old method, it has many unknown aspects. Materials and Methods: Nineteen patients participated in our study. The patients were divided into two groups as those who were treated immediately after the injury and those who applied in the late period. All patients were treated with pin and rubber traction systems (PRTS). After 6 weeks of traction, the fixator was removed. Patients were assessed with X-rays for the amount of distraction, Visual Analog Scale score for pain and quick DASH scores for satisfaction. The patients were also examined for passive and active range of motion (AROM) in all controls. Results: We compared the preoperative and postoperative data of the patients and also we compared the amount of distraction with functional gain. There was no relationship between the increase in PIP joint space distance and posttreatment PIP joint AROM values. Hence, the amount of distraction on the joint space distance has no direct effect on the functional results. Another important result of the study is that the loss of extension in the PIP joint, which can be unregarded in the early period, negatively affects the late results. The other important result of our study is that successful results can be obtained when applied in combination with surgery in delayed cases. Conclusion: The use of PRTS has an important role in the treatment of PIP joint injuries. In our study, we have shown that satisfactory results can be obtained in both acute and delayed cases when combined with additional surgery or applied alone. The change in joint space distance during the patient follow-up is not an important issue in terms of range of motion. Another important result we obtained from the study is the demonstration that PRTS can be successfully used in untreated joint dislocations in a single stage.