[A new fluoroscopic view to evaluate the medial and lateral articular reduction quality in patella fractures during internal fixation].

Objective: To introduce a new fluoroscopic method for assessing the quality of medial and lateral joint surface reduction during internal fixation of patellar fractures and to summarize the clinical outcomes of patients treated using this method. Methods: A retrospective analysis was conducted on the clinical data of 52 patients with patellar fractures treated between January 2018 and January 2022 who met the inclusion criteria. There were 27 male and 25 female patients, aged 21-75 years, with an average age of 62 years. The types of patellar fractures included 9 transverse fractures, 37 comminuted fractures, and 6 longitudinal fractures. According to the AO/Orthopaedic Trauma Association (AO-OTA)-2018 fracture classification, there were 21 cases of type 34A, 6 cases of type 34B, and 25 cases of type 34C. The time from injury to operation ranged from 1 to 5 days, with an average of 2.3 days. Treatments included internal fixation with hollow screws or hollow screw tension bands, with or without anchor repair. During operation, the medial and lateral joint surfaces of the patella were observed using the tangential fluoroscopic method to assess the smoothness of reduction of the median ridge, lateral joint surface, medial joint surface, and lateral joint edge. Patients were followed up regularly, and X-ray films were taken to observe fracture healing. Knee joint range of motion, Böstman score, and Lysholm score were used to evaluate functional recovery. Results: The tangential fluoroscopic method for the medial and lateral joint surfaces of the patella during operation showed satisfactory reduction of the joint surfaces and good positioning of the implants. All patients were followed up 12-16 months, with an average of 13.4 months. During the follow-up, fracture displacement occurred in 1 case and titanium cable breakage in 1 case. All patella fractures healed successfully, with a healing time of 8-16 weeks (mean, 11.4 weeks). At last follow-up, knee joint range of motion ranged from 120° to 140°, with an average of 136°. The Böstman score ranged from 20 to 30, with an average of 28, yielding excellent results in 45 cases and good results in 7 cases. The Lysholm score ranged from 88 to 100, with an average of 93, yielding excellent results in 40 cases and good results in 12 cases. Conclusion: The intraoperative application of the tangential fluoroscopic method for the medial and lateral joint surfaces of the patella can quickly determine the fluoroscopic plane of the patella, accurately assess the quality of fracture reduction and the position of internal fixator, thereby improving effectiveness.

Reconstruction of patella fractures with the tension band technique: A review on clinical results and tips and tricks.

INTRODUCTION: The goals of surgical treatment of patellar fractures are a biomechanically stable joint and congruent restoration of the retro patellar joint surface. Surgical treatment strategies for patellar fractures have evolved from tension band in combination with wire cerclages to new devices. METHODS: The modified anterior tension band (MATB) technique for fixation of patellar fractures consists of two longitudinal 1.8 mm Kirschner wires (K-wires) and an 18-gauge stainless steel wire looped in a figure-of-8 pattern over the anterior aspect of the patella. The K-wires should be inserted 5 mm from the anterior cortical surface of the patella, parallel in the coronal and sagittal planes. For mechanical reasons, the wire should be the closest to the anterior aspect of the bone. This construct converts the anterior tensile forces generated by the extensor mechanism and knee flexion into compressive forces on the anterior aspect of the fracture site. The MATB is the most widely accepted method of internal fixation for transverse and comminuted patellar fractures. Only a careful implementation of the MATB in all its phases will provide the best mechanical construct and the least aggressive construct for the soft tissues, allowing early re-education without complications. RESULTS: Good to excellent clinical results (64-100 %) have been reported with MATB for fixation of patellar fractures. Good to excellent range of knee motion and satisfactory results have been reported despite a high percentage (up to 60 %) of secondary procedures, mainly for removal of symptomatic hardware. CONCLUSION: This article provides an overview of the use and results of the MATB technique for patellar fractures and the means to improve results with this technique.

Tension band versus locking plate fixation for patella fractures - a protocol of a randomised controlled trial.

INTRODUCTION: Following surgical management of patella fractures, patients commonly report pain; difficulties with weight-bearing tasks such as walking, running and climbing stairs; and restrictions in quality of life. Recently, a locking plate system for surgical management of patella fractures has been introduced. To date, no studies have compared standard treatment with tension band wiring with locking plate fixation in a randomised study design. We aim to compare the one-year patient-reported Knee Injury and Osteoarthritis Outcome subscale scores (KOOS5-subscales) after standard care tension band fixation with locking plate fixation for patients with patella fractures. METHODS: This is a multicentre randomised and prospective clinical trial. A total of 122 patients will be included in the study, and the primary outcome will be the KOOS subscales at 12 months after surgery. CONCLUSIONS: Findings from the present study are expected to advance our understanding of outcome following surgical treatment of patella fractures. FUNDING: This study is funded, in part, by the Novo Nordisk Foundation, Denmark. CLINICALTRIALS: gov ID: NCT04891549.

[Clinical application of anatomical locking plate in treatment of Rockwood type â - â ¢patella fractures].

Objective: To investigate the effectiveness of anatomical locking plate in the treatment of Rockwood type Ⅰ-Ⅲ patella fractures. Methods: The clinical data of 16 patients with patella fractures who were admitted between November 2021 and January 2023 and met the selection criteria was retrospectively analyzed. There were 14 males and 2 females, with an average age of 44.5 years (range, 19-72 years). Causes of injuries included tumble in 12 cases and traffic accident in 4 cases. The fractures were rated as type Ⅰ in 2 cases, type Ⅱ in 9 cases, and type Ⅲ in 5 cases according to Rockwood classification criteria. The time from injury to operation ranged from 6 to 15 days, with an average of 9 days. After fracture reduction, an appropriate anatomical locking plate was selected for internal fixation. The operation time, intraoperative blood loss, and incision healing were recorded; the Lysholm score, Böstman patella fracture efficacy score, knee joint mobility, and visual analogue scale (VAS) score were used to evaluate the knee joint function and pain degree; X-ray films were used to review the fracture reduction and healing. Results: The operation time was 65-100 minutes (mean, 75.3 minutes); the intraoperative blood loss was 10-35 mL (mean, 25.6 mL). All incisions healed by first intention after operation. All patients were followed up 11-26 months (mean, 19.7 months). X-ray films showed that the fractures were reduced satisfactorily, and all achieved bony healing with healing time of 3-5 months. At last follow-up, the Lysholm score was 90-95 (mean, 93.0); the Böstman patella fracture efficacy score was 27-30 (mean, 28.8), of which 12 cases were excellent and 4 were good; the VAS score was 0-1 (mean, 0.3). There was no significant difference in the range of motion of the knee joint between the healthy and affected sides [145° (140°, 150°) vs 145° (140°, 145°); Z=1.890, P=0.059]. Conclusion: Choosing anatomical locking plates for Rockwood typeⅠ-Ⅲ patella fractures can achieve strong fixation with minimal surgical trauma, rapid recovery of knee joint function, and mild pain after operation.

Dorsal Hook Plating of Patella Fractures With Immediate Range of Motion Results in Reliable Fixation, Low Implant Removal Rates, and Satisfactory Clinical Outcomes.

OBJECTIVES: To evaluate radiographic and clinical patient-reported outcomes following dorsal hook plating of displaced patella fractures with permittance of immediate postoperative active closed chain range of motion. DESIGN: Retrospective review of prospectively collected data. SETTING: Urban academic level 1 trauma center. PATIENT SELECTION CRITERIA: Adult patients with displaced patella fractures (OTA/AO 34C1-3) who underwent dorsal plating with immediate range of motion between 2018 and 2023. OUTCOME MEASURES AND COMPARISONS: Numerical Rating Scale for Pain, Knee Outcome Score (KOS-ADL), Tegner-Lysholm score, radiographic union, and wound complications were collected. RESULTS: Sixty-one patients were included (47 female) with an average age of 63 years (SD 14.7, range 22-86 years). The mean BMI was 24.2 (SD 3.6, range 16.6-33.3). There were 13 34-C2 and 48 34-C3 fractures. All but 2 patients (96.7%) achieved bony union after the index procedure. 89% (n = 54) of patients completed outcome surveys with at least 6-month follow-up. Six patients (9.8%) underwent removal of plate implant at a mean of 15.1 months postoperatively. The mean KOS-ADL score was 91.4, the mean Tegner-Lysholm score was 78.1, and the mean NRS was 2.7. CONCLUSIONS: Dorsal hook plating offers secure fixation to allow early range of motion, reliable fixation with low nonunion and implant failure rates, low implant removal rates, and satisfactory patient-reported outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Lateral rim variable angle locked plating versus tension band wiring of simple and complex patella fractures: a biomechanical study.

INTRODUCTION: Treatment of both simple and complex patella fractures is a challenging clinical problem. Although tension band wiring has been the standard of care, it can be associated with high complication rates. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. MATERIALS AND METHODS: Sixteen pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34-C1 or five-part complex AO/OTA 34-C3 patella fractures by means of osteotomies, with each fracture model created in eight pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior (central distal) fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring or a lateral rim variable angle locking plate. Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full extension. Interfragmentary movements were captured via motion tracking. RESULTS: For both fracture types, the articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, lateral rim variable angle locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

High risk of complications following surgical treatment of patella fractures - a cross-sectional study of 798 patients with mean 6.4 years follow-up.

PURPOSE: This study aimed to investigate the incidence of early and late complications following treatment of patella fractures. Secondary aims were to investigate the association between early and late complications and the patient-reported outcome measurement, the Knee Injury and Osteoarthritis outcome score (KOOS). METHODS: Cross-sectional study including all patients recorded with a patella fracture residing in the Northern Region of Denmark between 2010 and 2020. Early (before 3 months) and late complications were investigated by retrospective review of charts and x-rays. All patients were invited to participate in the study by reporting current knee-specific symptoms. The KOOS was used to investigate patient-reported knee-specific symptoms. RESULTS: Seven hundred ninety-eight patients were included in the study. A total of 532 (67%) patients were treated conservatively, and 266 (33%) patients underwent surgery. The mean age at the time of fracture was 66.8, ranging from 6 to 103 years of age. The mean follow-up time was 6.4 years, ranging from 1.1 to 12.3 years follow-up. Overall, the rate of complications was 26%. Overall, the rate of complication for the surgical group was 57% and for the conservative group 4%. The most common early complication was the loss of reduction followed by the removal of symptomatic hardware. The most common late complication was the removal of symptomatic hardware and knee arthroscopy. In all the five KOOS subscales (Pain, Symptoms, ADL, Sport/Rec, and QOL), patients presenting with early and late complications reported statistically significantly worse scores than those without complications. CONCLUSION: The overall incidence of complications in patients presenting with a patella fracture was 26%, with a mean follow-up time of 6.4 years. In the surgical group, 57% of patients experience at least one complication during the follow-up period. Early and late complications were significantly associated with worse KOOS subscale  scores.

Comparative study of locking neutralization plate construct versus tension band wiring with a cannulated screw for patella fractures: experimental and finite element analysis.

Transverse patella fractures, accounting for approximately 1% of Orthopedic injuries, pose intricate challenges due to their vital role in knee mechanics. This study aimed to compare the biomechanical performance of a construct, integrating cannulated screws and an anterior locking neutralization plate, with the conventional tension band wiring technique for treating these fractures. Experimental testing and Finite Element Analysis were employed to evaluate the constructs and gain profound insights into their mechanical behavior. Sixteen cadaveric knees were prepared, and transverse patella fractures were induced at the midpoints using a saw. The plate construct and tension band wire fixation were randomly assigned to the specimens. A cyclic test evaluated the implants' durability and stability, simulating knee movement during extension and flexion. Tensile testing assessed the implants' maximum failure force after cyclic testing, while Finite Element Analysis provided detailed insights into stress distribution and deformation patterns. Statistical analysis was exclusively performed for the experimental data. Results showed the plate enhanced stability with significantly lower deformation (0.09 ± 0.12 mm) compared to wire fixation (0.77 ± 0.54 mm) after 500 cycles (p = 0.004). In tensile testing, the construct also demonstrated higher failure resistance (1359 ± 21.53 N) than wire fixation (780.1 ± 22.62N) (p = 0.007). Finite Element Analysis highlighted distinct stress patterns, validating the construct's superiority. This research presents a promising treatment approach for transverse patella fractures with potential clinical impact and future research prospects. This study presents a promising advancement in addressing the intricate challenges of transverse patella fractures, with implications for refining clinical practice. The construct's improved stability and resistance to failure offer potential benefits in postoperative management and patient outcomes.

Skyline view of the patella does not increase fracture detection: A non-inferiority diagnostic study.

PURPOSE: Patella fractures are frequent injuries in the adult population. Initial study is made by plain radiographs and the standard set includes the skyline view of patella. Recommendation for use of this projection is variable among the experts, without data that support its performance in the diagnosis of patella fractures. The main purpose of this study was to determine the sensitivity of the antero-posterior and lateral view of the knee, without skyline view, in the diagnosis of patella fracture. METHODS: A retrospective non-inferiority diagnostic study was designed with all the knee trauma adult patients of an Emergency Department in a single center in five years. A random sample of all the consecutive patella fracture cases were taken to elaborate the case group. The control group was matched by sex and age. Two blinded orthopedic surgeons reviewed the cases and control radiographs and defined the presence of fracture, with or without skyline view, with a wash-out time of three weeks between the two evaluations. Non-inferiority was defined a priori at 90% of minimum sensitivity. RESULTS: 140 patients were evaluated (70 cases and 70 controls). Sensitivity of the set without skyline view was 92.86% (CI 95% 0.90 - 0.96) and the standard set was 97.86% (CI 95% 0.96 - 0.99), without significant differences (p = 0.1) CONCLUSION: Sensitivity of the plain radiograph set without skyline view is non-inferior to the standard set. The routine use of skyline view when suspecting patella fractures is questionable.

High return to sports rates after operative treatment of patella fractures.

BACKGROUND: Patella fractures are relatively rare fractures and only little is known about the postoperative return to sports after patella fractures. METHODS: This retrospective study presents information on functional outcome after operative treatment of patella fractures as well as time until return to sports and patients' complaints after open-reduction internal-fixation (ORIF) of patella fractures. RESULTS: Overall, 39 patients after ORIF of patella fractures were evaluated at our Level-I trauma center with a mean follow-up of 42 months. The mean time until return to sports was 7 ± 3.9 months. No significant difference was found for functional outcome with respect to body mass index (BMI) or age. Fracture consolidation was accomplished after a mean of 6.9 ± 2.9 months besides a relatively low complication rate of 5.1% (n = 2). CONCLUSION: The results demonstrate a high return to sports rate of 90.3%. However, only 51.6% were able to perform sports on their pre-injury level or above. Trial Registration The study was retrospectively registered at DRKS (No: DRKS00031146).

Predictors of postoperative complications of tension band wiring techniques for patella fracture: A retrospective multicenter (TRON group) study.

OBJECTIVE: The relationship between postoperative complications and operative techniques of tension band wiring (TBW) is not well studied. We aimed to evaluate the incidence of implant breakage, implant migration, and loss of reduction in patellar fractures treated with TBW and identify radiographic factors associated with these postoperative complications. METHODS: This multicenter (named, TRON group) retrospective study included 224 patients who underwent open reduction and internal fixation of patella fractures using TBW from January 2016 to December 2020. Radiographic findings were evaluated by experienced orthopedic surgeons, and radiographic outcomes were assessed for K-wire migration, implant breakage, and loss of reduction. Logistic regression analysis was performed to identify radiographic factors associated with postoperative complications. RESULTS: Implant migration occurred in 44 cases (19.6%), with bending of a single K-wire end identified as a significant risk factor (OR: 12.90; 95% CI: 4.99-33.30; P < 0.001). Implant breakage occurred in 43 cases (19.2%), with a large patella-tension band ratio (OR: 291.0; 95% CI: 19.60-4330; P < 0.001) and a wide distance between K-wires (OR: 1.15; 95% CI: 1.060-1.250; P = 0.001) identified as significant risk factors. Loss of reduction occurred in 5 cases (2.0%), but no significant risk factors were identified. CONCLUSION: This study highlights the importance of bending both ends of the K-wires and proper placement of the tension band and K-wires in reducing postoperative complications in patellar fractures treated with TBW. Further research is needed to better understand the risk factors associated with loss of reduction.

[Anterior plate osteosynthesis for multifragmentary patella fracture with additive stabilization of the distal pole using suture cerclage]. / Anteriore Plattenosteosynthese bei mehrfragmentärer Patellafraktur mit additiver Sicherung des distalen Pols mittels Faden-Cerclage.

OPERATION GOAL: The aims of the surgical treatment are the anatomical reduction of the articular surface and stabilization of a multifragmentary patella fracture with a distal pole fragment using plate osteosynthesis and additive suture tape cerclage to secure the distal fragment. INDICATION: Demonstration of the surgical procedure for a multifragmentary patella fracture in the knee joint of a male cadaver. SURGICAL TECHNIQUE: Start with a median prepatellar skin incision and splitting of the bursa and surrounding fascia. Lateral arthrotomy with proximal and distal extension for complete eversion and articular exposure of the multifragmentary fracture. The fracture is then reduced from the articular side using temporary K­wire fixation and reduction clamps, followed by screw osteosynthesis of the large fragments (e.g., distal and proximal poles). After selection of the plate it is fixed with locking screws. In addition, a suture cerclage according to Krakow and/or McLaughlin is applied distally and transosseously through the tibial tuberosity and proximally through the quadriceps tendon. The knotting of the McLaughlin suture cerclage should be done in 90° flexion of the knee joint. POSTOPERATIVE TREATMENT: Functional postoperative treatment with hard shell orthesis with movement limitation (30°, 60° and 90° for 2 weeks each) and partial weight bearing of 15-20 kg for 6 weeks is recommended. Full weight-bearing is only allowed in full extension. EVIDENCE: Plate osteosynthesis is biomechanically superior in comparison to the widely used tension band osteosynthesis. In multifragmentary fractures, additional augmentation with a suture tape cerclage seems to be appropriate. Due to the lack of study results there is currently no clinical evidence for this.

Medial patellofemoral ligament reconstruction using patella bone tunnel techniques with or without implants. A systematic review of outcomes and complications.

PURPOSE: Τhe main goal of this study was to compare the clinical results, including the complication rates and patient-reported outcomes, in patients who underwent surgery for recurrent patellar dislocation using different patellar tunnel fixation techniques. This study compared Medial Patellofemoral Ligament (MPFL) reconstruction implant free techniques against ones that used implants. METHODS: The present systematic review was conducted according to the PRISMA guidelines. The literature search was conducted in January 2023. We included patients who underwent isolated MPFL reconstruction for recurrent patellar instability. Patients with confirmed concomitant or prior ipsilateral knee procedures, multiligament injury, severe patellar dysplasia or less than 6 months of follow-up were excluded. MINORS and MCMS scores were used for the assessment of methodological quality. RESULTS: Data from 750 procedures were collected, of which 284 used implants to perform the procedure while in 455 an implant-free technique was used. Patient age at the time of surgery ranged from 11 to 60 years while the follow-up time of the studies ranged between 3 and 108 months. Postoperative Kujala (0.3, p = 0.89) and Lysholm (1.2, p = 0.26) scores were better in the implant-free techniques compared to implant-based. A higher rate of recurrent dislocation (OR 0.51; 95% CI 0.10-2.54, p = 0.4), subluxation (OR 0.20; 95% CI 0.40-0.88, p = 0.019) and stiffness (OR 0.76; 95% CI 0.33-1.72, p = 0.55) was noted in the implant-free techniques, while the implant-based techniques displayed increased incidence of patella fractures (OR 3.12; 95% CI 0.77-12.6, p = 0.09), reoperation (OR 1.69; 95% CI 0.78-3.65, p = 0.17) and infection (OR 2.07; 95% CI 0.46-9.32, p = 0.33). CONCLUSION: There was no significant difference between the 2 techniques in terms of patient reported outcomes. Regarding complications, MPFL reconstruction using implants demonstrated significant higher rate of patella fractures while the implant free technique showed a greater risk of subluxation.

A novel patella fracture fixation technique: finite element analysis.

INTRODUCTION: Patella fractures account for approximately 1% of all bone fractures. The tension band wiring technique has been used in surgical treatment. However, there is no clear information about the location of the K-wires in sagittal plane. Thus, a transverse fracture line was created in the patella finite element model and fixed with Kirchner (k) wires and cerclage at different angles and compared with two different standard tension band models. MATERIALS AND METHODS: A total of 10 finite element models were created to study AO/OTA 34-C1 patella fractures. Two models used the classical tension band method with either circumferential or 8-shaped cerclage wire. The other 8 models used K-wires placed at 45° or 60°, either alone or combination with cerclage wire. A force of 200 N, 400 N, and 800 N were applied at 45° knee angle and the resulting data fracture line opening, surface pressure and stress in the implants were analyzed through finite element analysis. RESULTS: When all the results are considered, it was determined that the K-wires 60° crossing at the fracture line and with cerclage modeling was superior to the other models. The diagonal placement of the K-wires with cerclage (could be 45° or 60° medium) was superior to the reference models. CONCLUSIONS: This study has shown that the new fixation method we propose could come to the fore as an alternative method to be used successfully in transverse patella fractures and lower complications. In transverse patellar fractures, the use of K-wires crossed at 60° may be a good alternative to the standard method.

Biomechanical evaluation of three fixation methods in a feline transverse patella fracture model.

OBJECTIVES: This study aimed to compare the biomechanical properties of three stabilisation techniques in feline patella transverse fractures and select the strongest method with potentially minimal complications. METHODS: Patella fracture was simulated in 27 feline cadaveric pelvic limbs (mean weight of the cadavers 3.78 kg), and the limbs were randomly grouped to be stabilised with one of the three stabilisation methods. The modified tension band wiring technique with a single Kirschner wire (0.9 mm) and figure-of-eight wiring (20 G) was applied to group 1 (n = 9). Group 2 (n = 9) was stabilised with a combination of circumferential and figure-of-eight wiring techniques with orthopaedic wire (20 G). Group 3 (n = 9) was stabilised with the same technique as group 2, but with #2 FiberWire. The knee joints were positioned and fixed in the neutral standing angle (135°) and tested by applying tensile force. The loads at gap formations of 1, 2 and 3 mm were recorded, and the maximum failure load was measured in each group. RESULTS: In all the loads at displacement (1, 2 and 3 mm), group 3 was significantly stronger than groups 1 and 2, respectively (P <0.017). Group 3 (261.0 ± 52.8 N) showed significantly stronger fixation in the maximum load compared with group 1 (172.9 ± 45.6 N) (P <0.017). No significant difference was observed between groups 1 and 2 (204.9 ± 68.4 N) or between groups 2 and 3. CONCLUSIONS AND RELEVANCE: This study shows that the combination of circumferential and figure-of-eight techniques with FiberWire is more resistant to displacement than metal wire in this ex vivo feline patella fracture model.

Anterior variable-angle locked plating versus tension band wiring of simple and complex patella fractures - a biomechanical investigation.

BACKGROUND: The aim of this study was to investigate the biomechanical performance of novel anterior variable-angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. METHODS: Sixteen pairs of human cadaveric knees were used to simulate two-part simple transverse AO/OTA 34-C1 and five-part complex AO/OTA 34-C3 patella fractures. The complex fracture pattern was characterized with a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral and an inferior fragment mimicking comminution around the distal patella pole. Eight pairs with simple fractures were split for fixation via either tension band wiring (TBW) through two parallel cannulated screws or anterior variable-angle locked plating, whereas other eight pairs with complex fractures were split for either TBW through two parallel cannulated screws plus circumferential cerclage wiring, or anterior variable-angle locked plating using a cortical caudo-cranial polar screw. Each specimen was tested over 5000 cycles with a range of motion from 90° flexion to full extension by pulling on the quadriceps tendon. Interfragmentary movements were captured by motion tracking. RESULTS: For both fracture types, the longitudinal and shear articular displacements, measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following anterior variable-angle locked plating versus TBW, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, anterior locked plating of both simple and complex patella fractures resulted in less interfragmentary displacement under extended cyclic loading.

Periprosthetic patella fractures in total knee replacement and revision surgeries: how to diagnose and treat this rare but potentially devastating complication-a review of the current literature.

PURPOSE: Periprosthetic patella fractures (PPPFs) are infrequent but potentially devastating complications after total knee arthroplasty (TKA) and revision TKA (rTKA). These fractures may occur both in resurfaced and un-resurfaced patella. This review summarizes the current literature on PPPFs to help orthopedic surgeons diagnose and treat this uncommon but extremely challenging TKA complication. METHODS: A comprehensive search was performed in three databases: PubMed, SCOPUS, and EMBASE. All relevant information was retrieved and summarized in this narrative review. RESULTS: In the studies analyzed, there is a general trend in favor of nonsurgical treatment, except for implant loosening or extensor lag with extensor apparatus disruption, because surgery is often associated with poor clinical outcomes and high complication rates. CONCLUSION: PPPF is a rare but catastrophic event in TKA and rTKA, occurring mainly in a reconstructed patella. Patient-, implant-, and surgical technique-related factors contribute to its multifactorial etiopathogenesis. Prevention plays a crucial role in reducing the PPPFs rate. Conservative management is the treatment of choice due to high surgery complication rates unless implant loosening, or extensor apparatus disruption occurs.