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

Abstract

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.

Tension Band Wiring of Patella Fractures: Mid-Term Radiological and Clinical Results

“…Although there are studies reporting patella baja after patella fracture in the literature, there is no study reporting an elongated patella case. After a patella fracture, the reported Patella Baja rate is up to 43.9% (22,23). Our rate of patella baja (16.7%) is within this limit.…”

“…Our rate of patella baja (16.7%) is within this limit. It has also been reported that patella baja does not affect clinical results in the short term (22).…”

Serial Change in Patellar Height after Tension Band Wiring of Patellar Fractures

“…It is well known that patella baja can occur after operative treatment for patellar fracture; however, the correlative factors for patella baja have been surprisingly poorly investigated. Sebastian et al [3] investigated patellar height after patellar fracture with a mean follow-up of 503.8 days. They found 20% and 14.5% of all enrolled patients had patella baja and alta, respectively.…”

“…Patellar fractures are a relatively common type of fracture, accounting for approximately 1% of all fractures [1,2]. Their peak incidence occurs during the third to sixth decades of life [3]. Operative treatment is required for about 30% of injured patients, with the primary indication being intra-articular incongruity exceeding 2 mm and loss of the knee joint's extensor mechanism [4].…”

“…Previous studies have reported that approximately 12% to 57% of patellar fractures exhibit patella baja after operative treatment [2,11]. The impact of postoperative patellar height on clinical outcomes remains a topic of debate [1,3]. Despite the relatively high incidence of patella baja after surgery, the predictive factors for patella baja have been surprisingly poorly investigated.…”