Application of a Shape-Memory Alloy Concentrator in Displaced Patella Fractures: Technique and Long-Term Results

Abstract

Operative treatment is usually recommended in displaced patella fractures. Several techniques have been advocated for internal fixation of patella fractures. Despite the relatively good clinical outcomes that have been demonstrated in many studies, postoperative morbidities such as fixation failure, nonunion, infection, and knee stiffness are not uncommon. We present a new alternative treatment technique for displaced patellar fractures. Between April 1995 and May 2005, we used the Nitinol Patella Concentrator (NTPC) to treat 156 consecutive patients with displaced patellar fractures. Injuries arose from vehicular accidents in 56 (35.9%) cases, direct falls onto the knee in 85 (54.5%) cases, and sports injuries in 15 (9.6%) cases. The mean patient age was 46.3 years (range, 25-77 years). Clinical assessments were made using the Böstman knee score and the MOS SF-36 questionnaire (Medical Outcomes Study 36-item short-form health survey), which were both recorded at the final follow-up visit. The mean follow-up was 7.3 years (range, 6-17 years). At the final follow-up, the Böstman knee scores were excellent in 88 cases (28-30), good in 55 (20-27), and unsatisfactory in 13 (<20). According to the MOS SF-36 evaluation, the average score was 84.5 (range, 62-91). Treatment of patellar fracture with the NTPC not only may serve as an effective and rigid fixation method in multifragmented displaced and inferior pole fractures, but also may provide continuous concentrative compression during the osseous healing process. Thus, use of the NTPC may help restore the functional integrity of the extensor mechanism and permit early rehabilitation with a lower incidence of postoperative complications.

The Clinical Outcome of the Reduction of the Patellar Inferior Pole Fracture with Wire Cerclage Through A Generated Bone hole, in Combination with Patellar Concentrator: A Retrospective Comparative Study

“…Fortunately, using the patellar concentrator abrogates the need to drill holes in the patella, which avoids the problem of fracture displacement caused by Kirschner wire or screw implantation.In addition,the design of the patellar concentrator conforms to the principle of the tension band, which places continuous pressure on the fracture end [17]. Hence, the patellar concentrator possesses advantages of both simple operation and early functional exercise, and is suitable for various types of patellar fractures [5,10].However, our results revealed that the patellar concentrator alone produces poor reduction of the inferior patellar pole fracture. Lateral comminuted fractures were earlier shown to be di cult to x with patellar concentrator alone [18], so multiple C-arm uoroscopies are needed to ensure proper reduction.…”

Clinical outcomes of Ti-Ni shape-memory patella concentrator combined with cannulated compression screws in the treatment of C2 and C3 patella fracture: a retrospective study of 54 cases

“…However, the TNSMPC can fix the fracture independently by its claws and causes no extra bone loss, which can achieve excellent outcomes in osteoporotic or comminuted cases. The study conducted by Yutong Zhang et al, described another similar patella concentrator and reported desired outcomes in pole fracture or comminuted patella fractures [ 21 ]. Fracture displacement due to the loosening of the claw is a potential complication of the operation while it did not happen in cases with comminuted fractures.…”

Clinical outcomes of Ti-Ni shape-memory patella concentrator combined with cannulated compression screws in the treatment of C2 and C3 patella fracture: a retrospective study of 54 cases

“…The study conducted by Yutong Zhang et al described another similar patellar concentrator and report desired outcomes in pole fracture or comminuted patellar fractures. [21] Fracture displacement due to the loosening of the claw is potential complications of the operation while it did not happen in cases with comminuted fractures. Figure 5 shows the failure of the internal fixation in a case with a simple transverse fracture and the revision surgery was performed by removing the screws, reducing the fracture and fixing it with the claw and additional circle wire.…”