Patellafrakturen

Anterior Locking Plate Osteosynthesis of Patellar Factures - Analysis of Complications and Functional Outcome

BACKGROUND

Tension band wiring is the standard procedure for patellar fractures, but is associated with a high rate of implant related complications and implant failure. Tension band wiring may fail, especially with multifragmentary and comminuted fractures. Plate fixation of complex patellar fractures seems to be superior to wiring, both clinically and biomechanically. The aim of this study was to evaluate complications after locking plate fixation in patellar fractures two years after surgery and to access the functional outcome.

MATERIAL AND METHODS

As part of a prospective case series, all patients who had received locking plate fixation of a patellar fracture between April 2013 and May 2018 were clinically examined two years postoperatively and potential complications were evaluated.

RESULTS

A total of 38 patients aged 19 - 87 years were included. Complications occurred in a total of five patients (13%), including one reactive prepatellar bursitis, one chronic infection and loss of reduction due to a dislocated pole fragment in three cases. The average active range of motion of the affected knee joint two years postoperatively was 133°. The Tegner activity scale score reached 3 points, the Lysholm score 95 points and the Kujala score 95 points.

CONCLUSION

With an overall relatively low complication rate and good clinical outcome, dislocated distal pole fragments are a common complication after plate fixation of patellar fractures. If preoperative diagnostic testing shows a pole fragment, a modified hook-plate can be used, with the possibility of fixing the pole fragment.

Influence of patella height after patella fracture on clinical outcome: a 13-year period

INTRODUCTION

The incidence of patella fracture is statistically low (0.5-1.5%) compared to other fractures of the extremities [Patella fractures 76(10):987-997, 2005]. In the latter research, patella fractures if treated surgically present an overall inferior functional outcome. Little is known about the influence of the postoperative patella height on the clinical outcome. Therefore, the aim of our study was to analyse the influence of the patella height on the patients' functional outcome after surgery.

METHODS

In this retrospective study the in-house trauma register of our level I University trauma center was screened for patients suffering patella fractures treated surgically. Patella height of the same patients was evaluated on lateral X-rays using the Insall-Salvati Ratio (ISR). The patients' X-rays were analyzed at two time points for the ISR, whereas group A presents ISR data right after surgery and group B data at the latest follow up (minimum 6 weeks). The change of mean ISR at both time points was tested for significance. The functional outcome was measured by the "Munich Knee Questionaire" (MKQ). These MKQ results of different patella heights and fracture types were compared.

RESULTS

The screening of our in-house trauma register revealed 375 patients between the years 2003 and 2016. Out of these 54 patients (34f, 20 m) were enrolled. In detail the follow-up time for ISR between group A and B accounted for a mean of 503.8 ± 655.7 days. The MKQ was assessed at a mean of 1367.0 ± 1042.8 days after surgery. According to the AO-classification 10% AO.34 type B and 90% AO.34 type C fractures were found. Group A showed in 9.1% a patella baja and in 27.3% a patella alta compared to group B presenting 20.0% patella baja and 14.5% patella alta. There was no significant difference in functional outcome referring to the MKQ in patella alta (MKQ 69.0% ± 18.2) or baja (MKQ 67.1% ± 17.9) (p = 0.9). No significant functional difference between AO34.type B (MKQ 74.5% ± 11.0) and AO34.type C fractures (MKQ 64.0% ± 15.0) resulted (p = 0.1).

CONCLUSION

Our results demonstrate that different postoperative patella heights apparently do not influence the functional outcome in the short follow-up.

Functional Outcomes of Revision Osteosynthesis after Failure of Surgical Treatment of Patellar Fractures

Patellar fractures account for approximately 1% of all skeletal fractures. These fractures are rare; however, because of the crucial function of the patella in the extensor mechanism of the knee, they may lead to serious impairment. New data are revealing functional impairment remains common even with improved surgical techniques. The aim of this study was to assess the functional outcomes of patients after revision surgery in cases of secondary fracture dislocation or persistent articular incongruity. This study included 16 patients with a mean age of 51.8 years (range: 16-85 years) with a mean follow-up of 35.1 months. According to the AO/OTA classification, 15 patients had a C-type fracture, including 10 patients with C3 fracture. Thirteen patients were initially treated with tension band wiring via K-wires or cannulated screws. Revision surgery was performed because of persistent articular incongruity in five patients and secondary fracture dislocation or refracture in 11 patients. We analyzed pain (visual analog scale [0-10]), satisfaction, range of motion (ROM), Böstman's score, Lysholm's score, and knee injury and osteoarthritis outcome score (KOOS) after revision surgery and could extract follow-up data from 15 patients. Mean pain score at rest was 0.57 (range: 0-3.5) and on exertion 2.79 (range: 0-8). The measurement of the ROM of the affected knee compared with that of the opposite knee revealed complete extension. Mean flexion was 123 degrees, in the corresponding knee it was 136 degrees (p = 0.05). The mean postoperative Böstman's and Lysholm's scores were 25.11 (good, maximum: 30) and 78.67 (moderate, maximum: 100), respectively. KOOS was as follows: symptoms, 66.8 points; pain, 77.55 points; activity of daily living (ADL), 75.67 points; and quality of life, 56.25 points. The results of this study suggested that early revision surgery after failure of primary osteosynthesis with secondary anatomic reconstruction and good radiological results leads to satisfactory functional outcomes with persistent functional deficits.

[Fractures of the patella]

With 1% of all skeletal fractures patellar fractures are rare. The majority of cases are caused by a direct trauma to the flexed knee. The diagnosis is made via the injury mechanism as well as the physical and radiological findings. In conventional x‑ray imaging the extent of injury often is underrated, which mostly leads to the necessity of a computed tomography (CT) scan. The aim of the treatment is the reconstruction of the extensor mechanism and the anatomical reconstruction of the articular surface. The type of treatment depends on the fracture type. Tension band wiring still is the most frequently practiced technique. Complications, such as secondary dislocation or migration of the K‑wires resulting in revision surgery have been described in up to 30% of the cases. Studies could already show a higher biomechanical stability of osteosynthesis via cannulated screws. Especially in cases of comminuted fractures, osteosynthesis via a locking plate seems to have several advantages but long-term results are not yet available.

[Plate osteosynthesis of patellar fractures]

OBJECTIVE

Anatomic reconstruction of the retropatellar articular surface and repair of the extensor mechanism of the knee joint. The osteosynthesis should allow immediate mobilization as part of an early functional postoperative rehabilitation protocol.

INDICATIONS

Displaced fractures of the patella, especially multifragment and comminuted fractures with a retropatellar incongruity or dislocation of >2 mm.

CONTRAINDICATIONS

Critical local soft tissue because of the risk of postoperative infection.

SURGICAL TECHNIQUE

Median skin incision. For simple (transverse) fractures, preservation of the soft tissue and reduction control via the index finger. For complex fractures, lateral arthrotomy and eversion of the patella. Reconstruction of the articular surface from the joint side with optimal visibility. Temporary fixation with Kirschner wires, osteosynthesis with the fixed angle plate. If necessary, additional screws or wires.

POSTOPERATIVE MANAGEMENT

Immediate mobilization with full weightbearing in full extension with a knee brace. Extension/flexion 0/0/60° for 4 weeks, then 0/0/90° until the 7th week. Active extension after 6 weeks. Climbing stairs after 12 weeks.

RESULTS

Good functional results in combination with a low rate of complications and revisions.