Elsevier

Injury

Volume 51, Issue 2, February 2020, Pages 473-477
Injury

Patella fractures treated with cannulated lag screws and fiberwire® have a high union rate and low rate of implant removal

https://doi.org/10.1016/j.injury.2019.10.002Get rights and content

Highlights

  • Hardware irritation is a major cause for reoperation in fixation of patella fractures.

  • Suture cerclage is a powerful adjunct to the screw fixation of the transverse patella fracture without increase rate in hardware irritation. This leads to lower levels of hardware removal.

  • High union rate is expected with utilization of the suture cerclage in treatment of transverse patella fractures.

Abstract

Objectives

The purpose of this study is to report the results of open reduction internal fixation of patella fractures (OTA 34 A-C) using cannulated lag screws and FiberWire® (Arthrex, Naples, FL, USA) with regard to union and symptomatic implant removal.

Design

Retrospective review of prospectively collected database.

Setting

Urban Level 1 trauma center and Level 2 trauma center

Methods

All displaced intra-articular patella fractures (OTA 34 A-C) treated with ORIF by cannulated lag screws and FiberWire® tension band/cerclage between January 1, 2009 and August 1, 2018. Three hundred and eighty seven consecutive patients were identified. Fifty fractures were included in the final analysis.

Main Outcome Measurement

All patients were followed to clinical and radiographic union. Nonunion was defined as lack of clinical and radiographic union, fracture displacement, and/or return to OR for revision surgery. Rate of symptomatic implant removal was recorded.

Results

Average age was 57.7 years (range 21–86). Average follow up was 20.6 months (range 6–98 months). Average time to clinical and radiographic union was 3.1 months (range 3–7 months). Four fractures were open. There was a 96% (48/50) rate of primary union, with one patients requiring revision surgery to achieve union, and one developing an asymptomatic radiographic nonunion. The rate of symptomatic implant removal was 8% (4/50). Only 1 of the 4 was operated for a prominent suture knot, and the remaining 3 were for prominent screw removal. Knee range of motion averaged 0.37° extension to 119° flexion (range, 0–150°).

Conclusion

Patella fractures can be treated with cannulated lag screws and FiberWire® with a high rate of primary union (96%) and a low rate of symptomatic implant removal (8%). The implant removal rate compares favorably with alternative constructs, with an equivalent rate of fracture union.

Introduction

Multiple constructs have been utilized for the fixation of patella fractures with high rates of union [1,3,5,[14], [15]]. Traditional tension band constructs include parallel Kirschner wires inserted across the fracture and stainless steel wire placed around the K-wires and over the anterior aspect of the patella in a figure-of-eight fashion. Patella fractures treated with traditional tension band fixation are associated with complications reported to be between 18% and 50% of patients [1,2]. Reported complications include broken implants, migrating wires, and irritation due to symptomatic implants requiring removal of hardware in up to 38% of patients in some series [3].

Another construct option for patella fractures amenable to routine fixation is longitudinal cannulated lag screws with a modified anterior tension band with steel wire or plate fixation [14], [15], [16]. Carpenter showed that 4.0 mm cannulated screws with anterior steel wire tension band had significantly less fracture site displacement and significantly higher loads to failure when compared to traditional K-wires plus tension band [4]. Clinically, this has been shown to have similar union rates with lower rates of symptomatic implants, when compared to the traditional K-wire fixation method. However, the reported rates of elective implant removal are still high, 37% in the K-wire group and 23% in the screw group [5,13]. This has led some surgeons to seek alternative materials in order to decrease the rate of reoperation by substituting nonabsorbable heavy suture tension banding techniques instead of metal wire. Wright et al. showed that FiberWire® (Arthrex, Naples, FL, USA) had less stiffness when compared to stainless steel, but that FiberWire® was superior in failure strength. The authors concluded that FiberWire® was superior in strength to stainless steel in the maintenance of a tension band under force [6]. More recently, Bryant et al. biomechanically demonstrated no difference in fracture displacement or load to failure when comparing cannulated screws with FiberWire® vs cannulated screws and stainless steel wire for transverse patella fractures [7].

At our institution, we have utilized a technique for treatment of patella fractures amenable to routine fixation with partially threaded cannulated lag screws with an anterior FiberWire® tension band that is also supplemented with a FiberWire® cerclage. Biomechanical study of suture augmentation demonstrated improvement in maintenance of reduction [17]. In theory, this allows for improved fixation with cannulated screws, less soft tissue complications associated with steel wire, and similar rates of union. To our knowledge, no reports exist on the clinical outcomes of this technique. The purpose of this study is to report the results of open reduction internal fixation of patella fractures amenable to routine fixation (OTA 34 A-C) using cannulated lag screws and FiberWire® (Arthrex, Naples, FL, USA) with regard to union and symptomatic implant removal.

Section snippets

Patients and methods

After IRB approval, our prospectively collected database was retrospectively reviewed for all displaced intra-articular patella fractures (OTA 34 A-C) between January 1, 2009 and August 1, 2018. Three hundred and eighty seven consecutive patients were identified based on CPT code. Exclusion criteria were age <18, open reduction internal fixation other than with cannulated lag screws and FiberWire®, incomplete follow-up, malunion/nonunion/osteomyelitis referrals, non-operative management, and

Results

The average age was 57.7 years (range 21–86) and 68% were female. The average follow up was 20.6 months (range 6–98 months) with all patients followed to clinical and radiographic union. Fracture characteristics were as follows: AO/OTA type C (96%, n = 48); AO/OTA type A (2%, n = 1); AO/OTA type B (2%, n = 1). Of the 48 C-type fractures, 40 were C1 fractures, 8 were C2 fractures and zero C3 fractures. Forty-six fractures were closed, and four were open fractures (See Table 1).

There was a 96%

Discussion

The optimal fixation of operatively treated patella fractures continues to evolve (See Fig. 2). In the largest series to date, Hoshino reported on 448 patella fractures treated surgically. K-wire fixation with metal tension band were used for fixation in 315 (70%) patients and cannulated screws were used with tension band for fixation in 133 (30%). The incidence of fixation failure was 3.5% in the K-wire group and 7.5% in the screw group. The majority of the cannulated screw group tension band

Declaration of Competing Interest

Authors have no relevant conflict of interest to disclose to this topic.

References (17)

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    This result is important to put before clinicians as alternative treatment options might exist that provide similar fixation results but without the high risk of symptomatic implant removal. For example, Busel et al. [9] performed a retrospective review of 50 patella fractures treated with cannulated screws with FiberWire® (Arthrex, Naples, FL) tension band and cerclage construction which showed a high risk of union (96%) and low risk of symptomatic implant removal (8%). Of note, 48/50 patients had OTA/AO 34C fractures; however, none of the 48 patients had a comminuted fracture pattern, specifically OTA/AO 34C3, thus limiting the generalizability of the cannulated screws with FiberWire® construct for more complex fracture patterns.

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    A second benefit is that high-strength nonabsorbable sutures may provide a superior tension band construct than traditional metal wires.11 Fracture fixation with suture tension bands have demonstrated high rates of fracture union and excellent outcomes.18-20 Advantages of suture over metal wire include less hardware irritation with lower rates of revision surgery.6,7,12

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