Patellar fracture morphology varies based on the mechanism of injury. Most fractures are either a result of direct impact or through an indirect eccentric extensor contraction injury. Each fracture pattern requires appropriate preoperative planning and individualization of the fixation method. Displaced fractures affect the extension apparatus, and often require surgical fixation. Surgical treatment is recommended in fractures with any of the following features: articular step-off > 2 mm, > 3 mm of fracture displacement, open fractures, and displaced fractures affecting the extensor mechanism. Meticulous handling of the soft-tissue envelope is of the utmost importance, given the patella's tenuous blood supply and limited soft-tissue envelope. Incongruent articular surface can result in detrimental long-term effects; therefore, surgical treatment is directed toward anatomic reduction and fixation. The evolution of patellar fracture fixation continues to maximize options to balance rigid fixation with low-profile fixation constructs. Improving functional outcomes, minimizing soft-tissue irritation, and limiting postoperative complications are possible by using the therapeutic principles of rigid anatomical fixation and meticulous soft-tissue handling.

Patella Fractures: Approach to Treatment.

Background Patella fracture accounts for 1% of bone injury, of which anatomical reduction is of great significance to the recovery. Tension band with cannulated screw and Kirschner wire is commonly used methods for the treatment of displaced patella fracture. However, there is still some controversy on the clinical efficacy of the two treatment methods. Objective This study aimed at comparing the therapeutic effects of the cannulated screw and Kirschner wire tension bands on patella fracture and at providing more data basis for clinical selection of treatment methods for patella fracture. Methods Altogether, 146 patients with displaced patella fracture admitted to our hospital from March 2016 to February 2018 were selected and divided into two groups according to the different treatment methods. Among them, 71 patients received tension band with a cannulated screw (TBWCS group) and 75 patients received tension band with Kirschner wire (TBWKW group). Two groups of patients were compared in terms of surgical treatment effect after one year of treatment, complications within six months after the operation and operation-related indexes. The pain visual analogue scale (VAS) score, knee flexion degree, Lysholm score, and Bostman score were recorded at 1, 3, 6, and 12 months after operation, and the activity of daily living scale (ADL) score was evaluated at the last follow-up. Results During the operation of patella fracture patients, the intraoperative blood loss, hospitalization time, and knee flexion loss of patients in TBWCS group were less than those in the TBWKW group (P < 0.05), the starting time of postoperative functional exercise was earlier than that of patients in TBWKW group (P < 0.05), and the incidence rate of secondary operation was lower than that of patients in the TBWKW group (P < 0.05), but there was no statistical difference in the operation time, incision length, and postoperative fracture gap between the two groups. The results of curative effect analysis showed that the knee flexion, Lysholm score, and Bostman score of patients treated with tension band with cannulated screw were higher than those treated with Kirschner wire (P < 0.05), and VAS score was lower. Tension band with cannulated screw had a better curative effect on patella fracture (P < 0.05), lower complication rate (P < 0.05), and higher quality of life of patients (P < 0.05). Conclusion Tension band with cannulated screw has a good curative effect on patella fracture, low incidence of complications, early start of postoperative functional exercise, and high quality of life.

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Comparison of the Therapeutic Effects of Tension Band with Cannulated Screw and Tension Band with Kirschner Wire on Patella Fracture

Inferior pole fracture of the patella (IPFP) is difficult to repair and stabilize clinically. Although various fixation techniques have been developed, fixation strength and mobility remain daunting challenges to orthopedic surgeons. The goal of this research is to evaluate the biomechanical strength and clinical outcomes of a novel “fishing net” suture fixation procedure. Four finite element models, modified tension-band wiring fixation, anchor suture fixation, basket plate fixation and “fishing net” suture fixation were built to compare the fixing efficacy of “fishing net” suture fixation with three other fixation methods during IPFP fixation. From January 2018 to February 2019, 17 patients who suffered IPFP and treated by “fishing net” suture (FNS) fixation were compared with 20 patients treated by tension-band wiring (TBW) fixation in database and the two groups were evaluated postoperatively using the modified Cincinnati knee rating system. Biomechanical evaluation showed that the relative displacement values of proximal patella measured by three pairs of points on both sides of the fracture line were the lowest using the “fishing net” suture fixation, while fixation using tension-band wiring and basket plate showed similar levels of stability that were less desirable than the “fishing net” method. As to clinical outcomes, there were 17 (100%) patients exhibited excellent or good results with no internal fixation failures in the FNS group compared to three internal fixation failures in the TBW group. The biomechanical and clinical results suggest that the “fishing net” suture fixation is a viable candidate for fixation of IPFP.

“Fishing net” suture augmenting tension-band wiring fixation in the treatment of inferior pole fracture of the patella

Basic epidemiological data on patella fractures derived from large nationwide and multicenter studies are scarce. This observational register study describes patient epidemiology, fracture classification and treatment of patella fractures in adults in a Swedish population.We conducted an observational study on data derived from the Swedish Fracture Register (SFR) on all patella fractures classified as non-periprosthetic and non-pathological, registered between 2014 and 2018 in individuals aged ≥ 18years. Epidemiological data on sex, age, side, seasonal variation, trauma mechanism, fracture classification (according to AO/OTA), and treatment were analyzed.3194 patella fractures were analyzed, occurring at a median age of 67 (range 19-100) years. 64% of all patients were female. Most fractures were caused by low-energy trauma, with 70% due to falling from a standing height. 1796 (56%) of the fractures were transverse compared to 845 (26%) vertical fractures. Most fractures (N=2148, 67%) were treated non-operatively. Operative treatment consisted mainly of Tension Band Wiring (TBW) performed in 774 (24%) patients.Patella fractures mainly occur in elderly women (> 65 years), commonly caused by low-energy trauma. The main treatment is non-operative (67%), except for transverse (AO/OTA C3) fractures. TBW remains the most used operative treatment of choice. These results may help health care providers, researchers and clinicians better understand the panorama of patella fractures in Sweden. 

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Epidemiology, classification and treatment of patella fractures: an observational study of 3194 fractures from the Swedish Fracture Register

To determine whether certain types of fixation and other factors associated with the fixation could be identified that predict an increased risk of symptomatic implant removal.We conducted a retrospective cohort study at our urban academic level 1 trauma center. Patients aged ≥18 years who underwent operative fixation for patella fracture were included. The primary outcome was symptomatic implant removal after operative fixation.Of the 186 study patients (mean age, 44 [SD 17] years, 65% male), 53 patients (28.5%) underwent symptomatic implant removal. Modifiable risk factors for symptomatic implant removal included the use of Kirschner (k)-wires (OR: 4.93; 95% CI, 1.89-14.10; p < 0.001), and a trend towards significance for implant prominence >5 mm (OR: 2.57; 95% CI, 0.93-7.93; p = 0.07). Symptomatic implant removal was also less likely in patients >45 years of age (OR: 0.14; 95% CI, 0.06-0.34; p < 0.01), of a racial minority (OR: 0.40; 95% CI, 0.17-0.88; p = 0.03), and a body mass index >25 kg/m2 (OR: 0.39; 95% CI, 0.18-0.84; p = 0.02). The final model demonstrated excellent prognostic performance, with an AUC of 0.83 (0.76-0.90).We identified both modifiable and non-modifiable factors associated with symptomatic implant removal in patients with patella fractures. Surgeons should be aware that the use of k-wires and any implant prominence exceeding 5 mm might be associated with increased odds of symptomatic implant removal in patients with patella fractures. 

Surgical factors associated with symptomatic implant removal after patella fracture.

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.

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

The purpose of this study was to determine the angular tolerance of the S1 and S2 segments to accommodate a transiliosacral screw across both sacroiliac joints. We hypothesized that the angular tolerance for transiliosacral screw placement would be more constrained than the angular tolerance for iliosacral fixation in pelves where a safe osseous corridor was measured. The cortical boundaries of the S1 and S2 sacral segments in 433 pelvic CTs were digitally mapped. A straight-line path was placed within each osseous corridor and extended across both SI joints past the outer iliac cortices. The diameter of the path was increased until it breached the cortex, geometrically determining maximum diameter (Dmax). Angular tolerance for screw placement was calculated with trigonometric analysis of the Dmax value of the corridor, and the average distance from the termination of the osseous corridor to the site of percutaneous insertion. Gender, age, and BMI were evaluated as independent predictors using binomial logistic regression. The transiliosacral angular tolerance for the S1 and S2 osseous corridors was 1.53 ± 0.57 degrees and 1.02 ± 0.33 degrees, respectively. 68.9% of S1 corridors and 81.1% of S2 corridors had a safe zone (corridor diameter ≥ 10 mm) for transiliosacral placement, 48.3% of the pelves had a safe zone for both corridors, while 5.1% had no safe zones. Females had a less frequent Dmax ≥ 10 mm at S1, 52% vs 67% (p = 0.001), and at S2, 64% vs 86% (p < 0.001). In conclusion, the angular tolerance of 1.53 and 1.03 degrees for the S1 and S2 segments, respectively, creating a narrow interval for safe passage of the trans-iliac and trans-sacral, with approximately 31.1% of patients not having a viable corridor for screw passage. A correlation exist between S1 and S2 corridors with Dmax ≥ 10 mm and the resulting increase in angular tolerance for safe passage of a transilioscral screw. Level Retrospective Cohort.

Gennadiy A. Busel

Papers

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

Corridor-diameter-dependent angular tolerance for safe transiliosacral screw placement: an anatomic study of 433 pelves.