Comminuted patellar fractures: The role of biplanar fixed angle plate constructs

Anterior variable angle locking neutralisation plate superiority over traditional tension band wiring for treating transverse patella fractures

Purpose

This paper investigates the biomechanical benefits of using hybrid constructs that combine cannulated screws with tension band wiring (TBW) cerclage compared to cannulated screws with anterior Variable Angle locking neutralisation plates (VA LNP). These enhancements can bear heavier loads and maintain the repaired patella's integrity, in contrast to traditional methods.

Method

Eighteen fresh-frozen human cadaver patellae were carefully fractured transversely at their midpoints using a saw. They were then divided into two groups of nine for subsequent utilisation. Fixation methods included Cannulated Screw Fixation added with either TBW or VA LNP Fixation Technique. Cyclic loading simulations (500 cycles) were conducted to mimic knee motion, tracking fracture displacement with Optotrak. After that, the constructs were secured over a servo-hydraulic testing machine to determine the load-to-failure on axial mode.

Results

The average fracture displacement for the anterior neutralisation plate group was 0.09 ± 0.12 mm, compared to 0.77 ± 0.54 mm for the tension band wiring with cannulated screw group after 500 cyclic loading. This result is statistically significant (p = 0.004). The anterior neutralisation plate group exhibited a mean load-to-failure of 1359± 21.53 N, whereas the tension band wiring group showed 780.1 ± 22.62 N, resulting in a significant difference between the groups (p = 0.007).

Conclusion

This research highlights the superior biomechanical advantage of VA LNP over TBW for treating simple transverse patella fractures with two cannulated screws. It also highlights how the TBW is still a valuable option considering the load-to-failure limit.

Level of Evidence

Not Applicable.

Transverse patella fracture fixation: A cadaveric biomechanical comparison of cannulated screws and anterior tension band versus low-profile, multiplanar mesh plating

INTRODUCTION

Multiplanar mesh plating of patella fractures has become more popular in recent years. It was the goal of this study to compare the biomechanical stability of cannulated screw with anterior tension band to multiplanar mesh plating for fixation of transverse patella fractures in cadaver specimens.

MATERIALS AND METHODS

Eight matched pairs of fresh frozen cadaveric knees were obtained and soft tissues dissected leaving the extensor mechanism, joint capsule, and retinaculum intact. Transverse fractures were created at the mid-portion of the patella. For each pair, one specimen was repaired using cannulated screws with anterior tension band, and the second was repaired using multiplanar mesh plating. Each specimen underwent cyclic extension loading with loads increasing by 1.1 kg after every 50 cycles. Interfragmentary displacement was measured at the end of each interval at both 5° and 45° of knee flexion angle, with fixation failure defined by >2 mm displacement.

RESULTS

The specimens fixed with multiplanar mesh plating survived more cycles and higher loads than the specimens fixed with cannulated screws with anterior tension band (p = 0.011 comparing survival plots). After 150 cycles of extension loading, 3 of 8 of the specimens fixed with screws/tension band had failed, whereas none of the mesh plated specimens had failed. After 400 cycles, 7 of 8 of the screws/tension band had failed, whereas half of the mesh plated specimens had failed.

CONCLUSIONS

While a more technically challenging and expensive technique, mesh plating for patella fractures appears to offer greater durability than traditional cannulated screw with tension banding.

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.

Retrospective study of patellar fractures and damage of accessory soft tissue based on MRI

BACKGROUND

To better understand the pathophysiological mechanisms of patellar fractures, MRI was utilized to identify the imaging signs of various types of patellar fractures.

METHODS

A retrospective study was performed using MRI images of 52 patients with patellar fractures. Observing the development of patellar and femoral morphology and the imaging manifestations of different fracture types, such as fracture displacement, and damage to accessory ligaments, tendons, and meniscus, type of joint cavity effusion, and damage to surrounding accessory bones were identified.

RESULTS

There were 21 tangential fractures (40.4%), 8 transverse fractures (15.4%), 8 longitudinal fractures (15.4%), 4 oblique fractures (7.7%), and 11 comminuted fractures (21.2%) among the 52 patients with patellar fracture. Tangential fractures begin at a younger age than the other four forms of fractures. When tangential fractures were compared to other types of fractures, medial patellar retinaculum and anterior and posterior cruciate ligament injuries were statistically significant (P< 0.05). The detection rate of trochlear dysplasia, type II and type III patellar was higher in patients with tangential fractures than in other fractures.

CONCLUSIONS

Tangential fractures are less common to cause anterior and posterior cruciate ligament injuries than other types of fractures, but they are more likely to cause medial patellar retinaculum injuries.

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.

To plate, or not to plate? A systematic review of functional outcomes and complications of plate fixation in patellar fractures

PURPOSE

Poor outcomes and high complication and reoperation rates have been reported with tension-band wiring (TBW) in the management of patellar fractures and particularly the comminuted ones. The purpose of this study was to investigate the functional outcomes and complication rates of patellar fractures managed with open reduction and internal fixation (ORIF) with a plate.

METHODS

MEDLINE, EMCare, CINAHL, AMED and HMIC were searched, and the PRISMA guidelines were followed. Two independent reviewers extracted the data from the included studies and assessed them for the risk of bias.

RESULTS

Plating of patellar fractures is associated with satisfactory range of movement (ROM) and postoperative function and low pain levels. We found a 10.44% complication rate and a low reoperation rate. Reoperations were mainly performed for metalwork removal.

CONCLUSION

ORIF with plating of patellar fractures is a safe alternative in the management of patellar fractures and may be associated with a lower complication and reoperation rate compared to TBW. Future randomized prospective studies are needed to validated the results of the present systematic review.

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.

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.

3D reduction combined with the modified Kirschner-wire tension band for the treatment of comminuted patella fracture

PURPOSE

A novel 3D reduction method combined with a modified Kirschner-wire tension band (3D MKTB) fixation method to treat comminuted patella fractures was introduced in this study. This study aims to evaluate the effectiveness and practicality of this novel technology.

METHODS

This study is a retrospective case series study. Twenty-eight patients with closed comminuted patella fractures were treated with the novel 3D MKTB fixation method. Radiographs of the knee were obtained at the routine follow-up to assess fracture healing and widening of the articular step-off. Clinical outcomes including the degree of pain on a visual analogue scale (VAS), range of motion, Lysholm, and Bostman grading scales were measured at the last follow-up. The mean follow-up was 39.8 ± 10.5 (range 26-62) months.

RESULTS

All patients had bony union at a mean of 11.4 ± 1.4 (range 9-14 weeks) weeks based on X-ray. No patient had evidence of internal fixation failure. Only two patients suffered from surgical complication. One patient suffered from postoperative superficial infection, and one patient suffered from internal fixation irritation. Articular step-off larger than 2 mm was not seen in any cases. The average VAS-related pain score was 0.5 ± 0.5 (range 0-1) points. The average range of motion was 0-138.6° ± 11.9° (range 90°-155°), all patients had full knee extension. The mean Lysholm and Bostman scores were 92.9 ± 3.5 (range 86-100 points) points and 28.5 ± 1.3 (range 24-30 points) points, respectively.

CONCLUSION

The novel 3D reduction technique combined with the modified Kirschner-wire tension band technique is an effective, safe, and simple treatment option for comminuted patella fractures.

LEVEL OF EVIDENCE

IV.

Multi-planar fixation of displaced, multi-fragmentary patella fractures in elderly patients with anterior locking plates and cerclage wires: preliminary results

PURPOSE

The purpose of this study was to evaluate the outcomes of displaced, multi-fragmentary patella fractures in elderly patients treated with anterior plating and cerclage wires.

PATIENTS AND METHODS

Between 2018 and 2020, patients aged at least 60 years old undergoing anterior plating and circumferential wiring for displaced, multi-fragmentary patella fractures with a minimum of 12 months follow-up were included. Fragments were reduced and circumferentially stabilized by loop wires, followed by multi-planar fixation with an anterior locking plate and multi-directional screws. Postoperative outcomes were evaluated with the Böstman scores and range of motion. Patients were also asked about symptomatic hardware as well as satisfaction with postoperative outcomes.

RESULTS

Sixteen patients with an average age of 71.8 ± 9.3 years old were followed up for an average follow-up was 25.1 ± 8.2 months. At the latest follow-up, the average Böstman scores were 27.2 ± 3.4, and active knee flexion was 123 ± 14°. Two patients complained pinpoint implant irritation and underwent implant removal. Another underwent implant removal due to cultural reasons. Fifteen patients were satisfied with the operative outcomes, and one was unsatisfied due to intermittent patellofemoral pain. Cerclage wire breakage was noted in nine patients on postoperative radiographs, but none elicited pinpoint pain. No wound complications, infections, nonunion or loss of reduction were observed.

CONCLUSIONS

Anterior locking plates and cerclage wires in tandem provide reliable multi-planar fixation for displaced, multi-fragmentary patellar fractures in elderly patients and resulted in favorable clinical outcomes.

Three-dimensional fracture mapping of multi-fragmentary patella fractures (AO/OTA 34C3)

Background

Multi-fragmentary patella fractures (MFPFs) are common patella fracture type. Low-profile plate fixation seems to be promising advancement in the treatment of such difficult fractures. There is no systematic morphologic study specifically for MFPFs to provide objective reference for the improvement of future implants and biomechanical models. This study aimed to delineate and quantify the location and spatial frequency of fracture lines, comminution zones, and coronal plane fragments in MFPFs using three-dimensional (3D) CT mapping technique.

Methods

A total of 187 MFPFs were retrospectively reviewed and analyzed. Fractures were digitally reconstructed from CT data, and fracture lines, comminution zones, and coronal fragments were graphically overlaid onto a 3D patella template. Fracture characteristics were summarized qualitatively based on the fracture maps and quantitatively on the counts and volume of each fragment. Furthermore, according to the classic fracture patterns concerning MFPFs, subgroup analysis was conducted.

Results

On average, we observed 7 fragments in each fracture, 3 of which were <1 cm³. Most fractures (81.2%) had coronal fragments on the anterior and/or posterior patella surfaces. We identified three classic patella fracture patterns: transverse with comminution, stellate, and “displaced comminuted” in 104, 54, and 29 knees, respectively. 3D maps demonstrated distinct distribution fracture patterns of fracture lines, comminution zones, and coronal fragments.

Conclusions

Supero-medial corner of the patella was seldomly involved, and might be used as the cornerstone for fixation. Coronal fragments were common on both anterior and posterior patella surfaces, justifying the application of anterior plate osteosynthesis characterized by multi-planar fixation. Comminution areas mainly concentrated in the lower half of the patella, potentially suitable for an implant in combination with sutures or circumferential cerclage wiring. The described 3D features of MFPFs could provide reference for the design of future implants and biomechanical models.

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

INTRODUCTION

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

The biomechanical and clinical results suggest that the "fishing net" suture fixation is a viable candidate for fixation of IPFP.

[Progress in the surgical treatment of the patellar fracture]

OBJECTIVE

To review research progress of surgical treatment of patellar fractures.

METHODS

The domestic and foreign literature about patellar fracture treatment in recent years was extensively consulted, and the advantages, disadvantages, and indications of various surgical treatments were summarized.

RESULTS

The patella plays an important role in knee flexion and extension activities, and the fracture significantly affects the patient's quality of life. At present, the surgical methods include open reduction and internal fixation and patella resection. The internal fixation methods include ring/binding patella fixation, tension band wiring and improved technology, tension band wiring combined with other methods, screw fixation (including absorbable screws), steel plate fixation, and patella fixator fixation. Each surgical method has different indications, advantages, and disadvantages. Choosing an appropriate treatment plan plays a crucial role in clinical prognosis.

CONCLUSION

There are many surgical treatments for patellar fractures. In order to improve the effectiveness and reduce postoperative complications, it is necessary to choose the most appropriate treatment strategy for the type of fracture.