Compressive screwing of transverse patella fractures provides better resistance to traction than tension band

Clinical Outcomes of Cannulated Screws versus Ring Pin versus K-Wire with Tension Band Fixation Techniques in the Treatment of Transverse Patellar Fractures: A Case-Control Study with Minimum 2-Year Follow-Up

Purpose. K-wire with tension band (KTB) technique has long been the primary surgical method for transverse patella fractures; however, it also has shortcomings. This study is aimed at evaluating the three different techniques to see whether the cannulated screw tension band (CSTB) or ring pin tension band (RPTB) techniques could decrease complications and achieve better knee function compared with KTB. Methods. We conducted a retrospective comparison of the KTB, CSTB, and RPTB fixation techniques. We selected and reviewed 90 patients (30 patients in each fixation group) with follow-up at least 2 years. Duration of operation, intraoperative blood loss, mean healing time, visual analog scale score, range of motion, Böstman score, Iowa knee score, modified Lysholm rating scale, and postoperative complications were compared. Multivariate analyses were performed to identify the independent risk factors for fracture healing time, postoperative complications, and knee function recovery. Results. After adjusting for confounding factors, multivariate regression analysis revealed that CSTB was 0.26 times (95% CI: 0.08-0.86, $p=0.027$ ) less likely to prolong fracture healing time, 0.20 times (95% CI: 0.06-0.64, $p=0.007$ ) lesser risk of postoperative complications, and more than four times (95% CI: 1.41-13.56, $p=0.011$ ) as likely to improve the knee function score compared with KTB. Besides, RPTB were also superior to KTB in reducing the incidence of postoperative complications (OR: 0.21, 95% CI: 0.07-0.64, $p=0.006$ ) and improved knee function score (OR: 3.96, 95% CI: 1.30-12.08, $p=0.016$ ); however, the CSTB group being more superior. In addition, AO/OTA C2 fractures (OR, odds ratio: 10.68, 95% CI: 1.30-87.70, $p=0.027$ ) and high-energy fracture (OR: 8.78, 95% CI: 1.57-49.17, $p=0.013$ ) were also associated with prolonged fracture healing time but not with postoperative complications and knee function. No significant differences in related indicators such as gender, age, BMI, AO/OTA classification, fracture side, injury mechanism, duration of operation, and intraoperative blood loss were detected among the three groups. Conclusion. This study demonstrated that the CSTB technique is superior to KTB and RPTB techniques in reducing the incidence of postoperative complications, and it also has advantages in accelerating fracture healing, achieving better VAS, ROM, and functional recovery. Further long-term large-sized prospective randomized trials are needed to evaluate the efficacy of the KTB in treating transverse patellar fractures.

Triangular configuration with headless compression screws in the fixation of transverse patellar fracture

A triangular configuration with three parallel cannulated screws is an established treatment for fixing transverse patellar fractures; however, the stability achieved with this approach is slightly lower than that attained with cannulated screws combined with anterior wiring. In the present study, triangular configurations were modified by partially or totally replacing the cannulated screws with headless compression screws (HCSs). Through finite element simulation involving a model of distal femoral, patellar, and proximal tibial fractures, the mechanical stability levels of the modified triangular configurations were compared with that of two cannulated screws combined with anterior wiring. Four triangular screw configurations were developed: three HCSs in a forward and backward triangular configuration, two deep cannulated screws along with one superficial HCS, and two superficial cannulated screws with one deep HCS. Also considered were two parallel cannulated screws (inserted superficially or deeply) combined with anterior wiring. The six approaches were all examined in full knee extension and 45° flexion under physiological loading. The highest stability was obtained with the three HCSs in a backward triangular configuration, as indicated by the least fragment displacement and the smallest fracture gap size. In extension and flexion, this size was smaller than that observed under the use of two deeply placed parallel cannulated screws with anterior wiring by 50.3% (1.53 vs. 0.76 mm) and 43.2% (1.48 vs. 0.84 mm), respectively. Thus, the use of three HCSs in a backward triangular configuration is recommended for the fixation of transverse patellar fractures, especially without the use of anterior wiring.

Comparison of minimally invasive percutaneous fixation and open reduction internal fixation for patella fractures: a meta-analysis

BACKGROUND

Open reduction internal fixation (ORIF) has long been the conventional procedure for managing displaced patella fracture. This surgical approach has certain drawbacks, which might affect clinical outcomes and patient prognosis. Minimally invasive percutaneous fixation (MIPF) was proposed to overcome these disadvantages. Few in-depth investigations have been performed to determine the superiority of MIPF over ORIF. The aim of this study was to compare the efficacies of MIPF and ORIF for patella fractures.

METHODS

The PubMed, Cochrane Library, Embase, and Scopus databases were searched for relevant studies from November 26 to December 17, 2020. Non-English publications and pediatric orthopedic articles were excluded. Statistical analysis was performed using Review Manager, version 5.4, with mean differences (MDs), standardized mean differences (SMDs), odds ratios (ORs), and respective 95% confidence intervals (CIs) calculated using a random effects model. The primary outcomes were the pain score, knee range of motion, and joint functionality. The secondary outcomes were the surgical time, complications, and implant removal rate.

RESULTS

Six articles with a total of 304 patients were included in the meta-analysis. Pooled analysis revealed that patients with MIPF had a significantly reduced pain score (MD = - 1.30, 95% CI = - 1.77 to -0.82; p < 0.00001) and increased knee extension angles (MD = 0.72, 95% CI = 0.18 to 1.25; p = 0.009) at 3-month follow-up. Furthermore, knee flexion angles (MD = 8.96, 95% CI = 5.81 to 12.1; p < 0.00001) and joint functionality (SMD = 0.54, 95% CI = 0.21 to 0.86; p = 0.001) had statistically improved at 2 years. However, no difference was observed between MIPF and ORIF with regard to the surgical time. The risk of complications (OR = 0.10, 95% CI = 0.05 to 0.18; p < 0.00001) and implant removal rate (OR = 0.20, 95% CI = 0.07 to 0.57; p = 0.003) were significantly lower with MIPF than with ORIF.

CONCLUSIONS

MIPF is more favorable than ORIF in terms of the pain score, knee range of motion, joint functionality, complications, and implant removal rate. Thus, it can be adopted as an alternative to ORIF.

Role of an additional third screw in the fixation of transverse patellar fracture with two parallel cannulated screw and anterior wire

BACKGROUND

Two parallel cannulated screws along with an anterior wire to construct a tension band is a popular approach in transverse patellar fractures. However, the optimal screw proximity, either deep or superficial screw placements, remains controversial. Hence, a new concept of the addition of a third screw to form a triangular configuration along with the original two parallel screws was proposed in this study. Therefore, the biomechanical effect of the additional third screw on the stability of the fractured patella was investigated with finite element (FE) simulation.

METHODS

An FE knee model including the distal femur, proximal tibia, and fractured patella (type AT/OTA 34-C) was developed in this study. Four different screw configurations, including two parallel cannulated screws with superficial (5-mm proximity) and deep (10-mm proximity) placements and two parallel superficial screws plus a third deep screw, and two parallel deep screws plus a third superficial screw, with or without the anterior wire, were considered for the simulation.

RESULTS

Results indicated that the addition of a third screw increased stability by reducing the dorsal gap opening when two parallel screws were deeply placed, particularly on the fractured patella without an anterior wire. However, the third screw was of little value when two parallel screws were superficially placed. In the existence of two deep parallel screws and the anterior wire, the third screw reduced the gap opening by 23.5% (from 1.15 mm to 0.88 mm) and 53.6% (from 1.21 mm to 0.61 mm) in knee flexion 45° and full extension, respectively. Furthermore, in the absence of the anterior wire, the third screw reduced the gap opening by 73.5% (from 2 mm to 0.53 mm) and 72.2% (from 1.33 mm to 0.37 mm) in knee flexion 45° and full extension, respectively.

CONCLUSION

Based on the results, a third cannulated screw superficially placed (5-mm proximity) is recommended to increase stability and maintain contact of the fractured patella, fixed with two parallel cannulated screws deeply placed (10-mm proximity), particularly when an anterior wire was not used. Furthermore, the third screw deeply placed is not recommended in a fractured patella with two parallel superficial screws.

Biomechanical comparison of three tension band wiring techniques for transverse fracture of patella: Kirschner wires, cannulated screws, and ring pins

PURPOSE

The purpose of this study is to compare biomechanical characteristics of tension band wiring using Kirschner wires (TBWKW), cannulated screws (TBWCS), and ring pins (TBWRP) for transverse fracture of the patella.

METHODS

A total of 48 polyurethane synthetic patellae were biomechanically tested. All patellae were osteotomized to create a transverse fracture. Each TBWKW, TBWCS, and TBWRP fixed 16 broken patellae. A specially designed fixation board simulated a knee with 90° flexion. Ten static tests and six dynamic tests were performed on each method. The static test is measuring maximum strength (N) during traction until breakage of the fixation. The dynamic test consisted of measuring the fracture gap (mm) after 10,000 repetitive loading cycles between 100 N and 300 N that simulated actual daily activity. A gap of 2 mm or more was defined as a failure in both tests.

RESULT

The failure load was 438.6 ± 138.6 N, 422.2 ± 72.7 N, and 1106.8 ± 230.3 N for TBWKW, TBWRP, and TBWCS, respectively. TBWCS showed a statistically significant difference compared to TBWKW and TBWRP in the static test (p < 0.001). All the groups had no failure in the dynamic test. The mean fracture gap after completion of the dynamic test was 0.3267 ± 0.3395 mm, 0.2938 ± 0.2165 mm, and 0.0360 ± 0.0570 mm for TBWKW, TBWRP, and TBWCS, respectively (p = 0.044). The mean values in the dynamic test showed no statistical difference. There was a significant difference between TBWRP and TBWCS (p = 0.009), but others showed no difference with statistical significance.

CONCLUSION

All three methods have sufficient stability at a daily activity. TBWCS showed a better failure load compared with TBWKW and TBWRP. TBWRP showed compatible mechanical characteristics with traditional tension band wiring. TBWRP could be an alternative method for TBWKW.

Efficacy of K-wire tension band fixation compared with other alternatives for patella fractures: a meta-analysis

Background

To compare the efficacy and safety of K-wire tension band fixation (KTB) with other alternative approaches (cannulated screws, cable pin, and ring pin) for treatment of patella fractures by performing a meta-analysis.

Methods

PubMed and EMBASE databases were searched for all relevant studies. Standardized mean difference (SMD) or relative risk (RR) and their corresponding 95% confidence intervals (CIs) were calculated for continuous or dichotomous outcomes via either a fixed- or random-effect model using Stata 13.0 software.

Results

Nine literatures involving 949 patients (581 in the KTB group and 368 in the control group) were included. Pooled analysis showed there were no differences in the success rate, operative time, healing time, and number of infections between patients undergoing KTB and others. However, the incidence of complications (RR = 8.04, 95% CI = 4.45–14.53; p < 0.001) and VAS (SMD = 0.642, 95% CI = 0.22–1.06; p = 0.003) were lower, while flexion degree (SMD = − 0.70 95% CI = − 1.04–− 0.36; p < 0.001), Böstman joint function score (SMD = − 0.68, 95% CI = − 1.10–− 0.27; p = 0.001), Iowa knee score (RR = 0.88, 95% CI = 0.81–0.96; p = 0.004), and Lysholm score (SMD = − 0.71, 95% CI = − 1.10–− 0.32; p < 0.001) were significantly higher in patients undergoing alternative approaches than the KTB. Subgroup analysis also demonstrated the cannulated screw fixation was superior to KTB in reducing the incidence of complications.

Conclusions

Alternative treatments may be effective for management of patella fractures and should be attempted to be popularized in clinic.

Comparison of the outcomes of cannulated screws vs. modified tension band wiring fixation techniques in the management of mildly displaced patellar fractures

BACKGROUND

K wire fixation with tension band wiring has conventionally been used for the open reduction and internal fixation of the patella. However, it suffers from distinct disadvantages such as implant irritation, need for open reduction, incidence of palpable implants, and need for subsequent implant removal. A smaller incision with percutaneous fixation may be an alternative to this established conventional technique. Thus, the purpose of this trial was to compare the treatment outcomes of patients with mildly displaced patellar fractures treated with closed reduction and percutaneous cannulated screw fixation (CRCF) as compared to open reduction and tension band wiring fixation (ORTF). Specifically, we aimed to determine whether cannulated screw fixation was associated with improved clinical outcomes at 12 months as measured using the Lysholm score, pain scores, degree of flexion, range of motion, time to radiographic union, radiographic outcomes, and complication rates.

METHODS

Sixty-three patients with transverse patellar fractures displaced less than 8 mm were included in this prospective, randomized, controlled trial, with 52 patients in the final data analysis. Thirty-two patients were operatively treated by CRCF with either two or three cannulated screws. Thirty-one patients were operatively treated by conventional ORTF using the modified tension band technique. At postoperative intervals of 3, 6, and 12 months, knee function was evaluated using the Lysholm score, pain was assessed using the visual analog scale (VAS) score, and active knee extensions and flexion were measured in degrees by goniometry.

RESULTS

The CRCF group had average Lysholm scores of 84.4 ± 5.8, 86.7 ± 6.4, and 93.2 ± 5.3 after 3, 6, and 12 months, respectively, which were significantly greater than those of the ORTF group (79.0 ± 5.3, p = 0.001; 81.5 ± 4.6, p = 0.002; and 89.8 ± 6.2, p = 0.039, respectively). Lower pain and squatting scores were the main reasons for the poorer Lysholm scores in the ORTF group. The VAS scores showed that the CRCF group had lower pain scores and better flexion and total range of motion (ROM) compared with the ORTF group after 3 and 6 months, although both groups had similar outcomes after 12 months. The mean fracture healing time of 2.65 months was similar in the CRCF groups (2.77 months; p = 0.440). Complication rates were 3/26 (11.5 %) in the CRCF group and 14/26 (53.4 %) in the ORTF group. Two patients in the CRCF group and eight patients in the ORTF group experienced skin irritation. In addition, two (7.7 %) patients in the CRCF group and 11 (42.3 %) patients in the ORTF group required implant removal because of symptoms due to the presence of the implants.

CONCLUSION

Surgical treatment of mild displaced (less than 8 mm) transverse patellar fractures by the CRCF technique provides satisfactory clinical results and excellent knee function, with little pain and a low incidence of complications at early follow-up (up to 6 months). These results suggest that the CRCF technique may be a superior alternative to conventional ORTF. Registration Trial (Chinese Clinical Trial Register): Current Controlled Trials ChiCTR-PRCH-14005017, registration dates 2014-06-14.

Biomechanical studies on transverse olecranon and patellar fractures: a systematic review with the development of a new scoring method

INTRODUCTION

Several methods of transverse patellar and olecranon fixation have been described. This article compares biomechanical studies of various fixation methods using a newly developed scoring method.

SOURCE OF DATA

The databases PubMed, Web of Science, Science Direct, Google Scholar and Google were searched for relevant studies.

AREAS OF AGREEMENT

Fixation hardware failure remains a problem. Various materials and fixation techniques have been tested to provide an improved fixation of transverse olecranon and patellar fractures.

AREAS OF CONTROVERSY

The difference in biomechanical testing setup between the studies makes it hard to compare different fixation techniques.

GROWING POINTS

The newly developed grading method was proved to be unbiased and reliable; however, extra specifications need to be added at some criteria when adopting the scoring method.

AREAS TIMELY FOR DEVELOPING RESEARCH

Non-metallic constructs may provide an improvement to the currently used metallic tension band wiring technique; however, clinical research is required.