Comparison of a Novel Tension Band and Patellotibial Tubercle Cerclage in the Treatment of Comminuted Fractures of Inferior Pole of the Patella

Abstract

Objective: To assess the therapeutic effect of a novel tension band using 3.0 mm cannulated screw combined with a titanium cable and specific shims comparatively with patellotibial tubercle cerclage in comminuted fractures of the inferior pole of the patella.

Methods: The retrospective study from March 2012 to July 2017 was conducted in Peking University Third Hospital and comprised 63 patients with comminuted fractures of the inferior pole of the patella: 41 treated with new tension band using 3.0 mm cannulated screw combined with a titanium cable and specific shims (new tension band group) and 22 with patellotibial tubercle cerclage (tubercle cerclage group). Gender, age, AO/OTA fracture type, injury mechanism, inter-fragmentary gap, and follow-up time of patients were recorded. Two groups were compared regarding: operation time, blood loss, partial weight-bearing time, fracture-healed time, Bostman score and knee mobility at 12-month follow-up, and postoperative complications. Continuous and categorical parameters were analyzed by Mann-Whitney U test and the chi-squared test, respectively. Fisher's exact test was used for small data subsets.

Results: Between the two groups, no statistically significant difference was found in mean age, gender, AO/OTA fracture type, injury mechanism, mean inter-fragmentary gap, or mean follow-up time (P > 0.05). The mean operation time of new tension band group was significantly longer than that of tubercle cerclage group (76.4 min vs 64.2 min, P = 0.006), while there was no significant difference in blood loss. After surgery, new tension band group had a significantly earlier mean partial weight-bearing time (5.2 weeks vs 7.4 weeks, P < 0.001) and fracture-healed time (9.6 weeks vs 11.6 weeks, P < 0.001). At 12-month follow-up, patients of new tension band group had a significantly higher mean Bostman score (28.5 vs 25.8, P < 0.001) and knee mobility (126.7 vs 117.3, P < 0.001). Ten complications related with internal fixation were found in tubercle cerclage group including two cases of loose internal fixation, two cases of cerclage breakage, and six cases of low patella position who undertook secondary operation. No complications were found in new tension band group (0 in 41 vs 10 in 22, P < 0.001).

Conclusion: Patients with comminuted fractures of the inferior pole of the patella treated with a novel tension band experienced a longer operation time, but earlier partial-weight-bearing and fracture-healed time, better clinical outcomes at 12-month follow-up, and less complications. It should be considered an alternative therapy for the treatment of distal pole patellar fractures.

Keywords: Cannulated screw; Inferior pole fracture of the patella; Patellotibial tubercle cerclage; Tension band.

Figure 1

(A) Male, 40 years old, slip accident, comminuted inferior pole fractures of the right patella (AO/OTA type: A1). (B) Fracture reduction, multiple K‐wires (φ1.5 mm and φ1.2 mm) temporary fixed. (C) Intraoperative fluoroscopy showing satisfactory fracture reduction.

Figure 2

(A) Aφ3.0 mm cannulated screw with a specially designed shim. (B) A φ1.3 mm titanium cable passed through the small hole of the shim; the cannulated screw, shim and titanium cable constitute a stable, fixed construction.

Figure 3

(A) Insertion of the φ3.0 mm cannulated screw with the special shim along the guide pin. The titanium cable passes through the small hole of the shim, then tightens the titanium cable and the cannulated screw. (B) The titanium cable passes through the bone hole of the widest part of the proximal patella, then tightens the titanium cable to form the figure‐of‐eight tension band at the anterior cortex of the patella, fixing the titanium cable with cable clamps.

Figure 4

(A) and (B) Anteroposterior and lateral radiographs of the knee postoperatively. (C–F) A total of 2 months postoperatively, the fracture was well healed; the right knee joint functioned normally, and normal walking function was restored (Bostman score: 30 points).

Figure 5

(A) Female, 55 years old, slip accident, right comminuted inferior pole fracture of the patella (AO/OTA type: A1). (B, C), Fracture reduction and internal fixation, 3.0 mm cannulatedscrew to fix the inferior pole fracture fragment. Patellotibial tubercle cerclage was performed. Postoperative X‐ray showing low position of the patella.

Figure 6

(A) and (B) A total of 8 weeks postoperatively, X‐ray radiography showed good internal fixation and fracture healing. (C, D) Knee activity was 10° to 100° 8 weeks postoperatively, without weight‐bearing walking.

Figure 7

(A) and (B) At postoperative 5 months, patellotibial tubercle cerclage breakage. (C, D) The patient's knee activity was 0°–125°, walking with soft leg symptoms, knee pain when climbing stairs; daily work intensity was reduced, with a Bostman score of 26 points; 5 months after surgery, a second surgery was performed to remove the implants.