[Fractures of the patella]

Tension band tendon-approximating cerclage for surgical fixation of patellar fractures: a novel surgical technique

Patellar fractures are potentially debilitating injuries due to loss of extensor mechanism function, resulting in an inability to extend the leg. Traditionally, these fractures have been surgically managed with open reduction and internal fixation using a tension band construct. This can be performed with K-wires or cannulated screws with suture or cable as the tension band. Plate osteosynthesis is another option that is increasing in popularity. Incorporating the tension band construct converts tensile force into a healing-compatible compressive force. However, these techniques often fail when used for comminuted patellar fractures. There is also a high reoperation rate due to metal implant discomfort. Reoperation rates have been reported as high as 41% for K-wires and 23% for cannulated screws. A more optimal technique would provide adequate reduction and strong fixation without the risk of implant irritation that can apply to all/most fracture types. We report a new technique that implements a multistrand, long-chain, ultra-high-molecular weight, polyethylene core suture material with a braided jacket of polyester (FiberWire) without the need for any associated plates, K-wires, or cannulated screws. The suture is woven to create a tension band tendon-approximating cerclage construct that incorporates the proximal and distal bone fragments as well as the patellar and quadriceps tendons. This technique can be used for both simple and comminuted fractures and provides optimal fixation strength while minimizing the complications associated with metal implants. The efficacy of this technique may lend to future studies including biomechanical and retrospective analyses.

Clinical and functional outcomes of locked plating vs. cerclage compression wiring for AO type C patellar fractures- a retrospective single-center cohort study

PURPOSE

Although "tension-band wiring" is still commonly used to stabilize patellar fractures, the technique has recently been scrutinized due to biomechanical insufficiency. Consequently, the AO Foundation renamed the principle to compression cerclage wiring (CCW). Several studies propose favorable outcomes when utilizing locked plating (LP). This study aims to compare outcome of CCW and LP for complex patellar fractures.

METHODS

A retrospective, single-center cohort study was performed on patients who underwent operative treatment for (AO 34 C-Type) patellar fractures between April 2013 and March 2023. Patients with a 12 month follow up were included. We grouped and compared patients based on the applied treatment strategy: group LP vs. group CCW. Primary outcome parameters included implant-related complications and revision surgeries. Secondary outcomes were length of stay, return to work and 12 months functional outcome (Lysholm score). Odd ratios for complications and revisions were calculated using the conditional Maximum Likelihood Estimate. The threshold for statistical significance was set at p < 0.05.

RESULTS

Of 145 patients, 63 could be included (group LP: n = 23 and group CCW: n = 40). Fractures in group LP were significantly more complex in regard to AO Classification (p < 0.001), number of fragments (p < 0.001) and degree of comminution (p < 0.001), yet odds of complications were significantly lower in group LP (OR: 0.147; 95%CI: 0.015-0.742; p = 0.009). K-wire migration was the most common complication in group CCW (20%). Odds of revision surgery were significantly lower in group LP (OR: 0.000; 95%CI: 0.000-1.120; p = 0.041). The average Lysholm score at one year was favorable in both groups (89.8; SD: 11.9 in group LP and 90.6; SD: 9.3 in group CCW; n.s.).

CONCLUSION

In our study cohort, LP was routinely chosen for more complex fracture morphologies; nevertheless the data implies that LP may be considered as the superior fixation technique in regard to complications and revision operations. Especially, K-wire migration occurs frequently after CCW. The one year functional outcome was comparable between the groups, with both demonstrating good results. Prospective randomized studies are indicated to validate our findings.

Radiographic and Functional Outcomes Following Resorbable Screw-Augmented Suture Fixation vs. All-Suture Fixation of Mid-pole Patellar Fractures: A Comparative Case Series

Purpose Midpole patellar fractures are traditionally fixed with an "11-8" metal tension band construct. However, this technique is rife with implant-related complications. This study aims to evaluate the radiographic and functional outcomes following "all-suture" fixation of mid-pole patellar fractures as compared to resorbable screw-augmented suture fixation. Methods We retrospectively studied a consecutive series of 18 patients, 9 each with mid-pole patellar fractures treated with all-suture fixation or suture fixation augmented with bioabsorbable cancellous screws in our institution. The hybrid fixation cohort was significantly older (p<0.01). Radiographic and functional outcomes, such as time to union, postoperative range of motion (ROM), and the presence of complications such as fracture displacement were recorded and evaluated. The minimum follow-up was one year. Results All cases achieved radiographic union by 15 weeks postoperatively except one from the hybrid fixation cohort. The average time to radiographic union was comparable (p=0.30). Twenty-two point two percent (22.2%; 2 out of 9) of the cases from each cohort had an increase in the fracture gap (>2 mm) at around four to six weeks postoperatively, for which all except one case from the hybrid fixation cohort achieved union thereafter. One patient from the hybrid fixation cohort had fibrous non-union and further fracture displacement. There was another case of mild fracture gapping and screw breakage on review of postoperative radiographs at three months from the hybrid fixation cohort. These patients recovered without surgical revision or implant removal. Conclusions Both non-metal fixation methods for mid-pole transverse patellar fractures proved to be radiographically and functionally comparable.

Cannulated compression screws with cable technique leads to a dramatic reduction in patella fracture fixation complications compared to tension band wiring

INTRODUCTION

The aim of this study was to compare the clinical, radiological and functional outcomes between cannulated compression screw with cable construct (CS) and tension band wiring (TBW) in transverse patella fractures.

MATERIALS AND METHODS

A retrospective study was conducted on patients surgically treated for AO/OTA 34C1 or 34C2 transverse patella fractures with CS or TBW technique between January 2019 and January 2023. Clinical outcomes included complications related to the implant, wound and fracture at 6 months and 1 year, time to achieving full weight bearing status and early perioperative clinical outcomes. Radiological outcomes included the time to fracture heals and delayed union. Functional outcome measures using the Oxford Knee Scale, 36-short form questionnaire and the Bartlett Anterior Knee Score were assessed.

RESULTS

73 patients were treated with CS (n = 33) or TBW (n = 40). TBW had higher complication rates: 25.0% (n = 10) required implant removal, 12.5% (n = 5) had wire breakage, 12.5% (n = 5) experienced fracture displacement while 52.5% (n = 21) experienced implant migration. In contrast, no CS patients had implant removals, wire breakage or fracture displacement and 3.0% (n = 1) experienced implant migration. At 1 day post-operatively, 87.9% (n = 29) CS group patients were able to ambulate as compared to the 55.0% (n = 22) of TBW patients. Furthermore, CS patients ambulated further distances at 11.8 ± 10.6 m than the TBW group (6.4 ± 7.4 m). The CS group (25.9 ± 24.6 days) also achieved full weight bearing status faster than the TBW group (43.6 ± 39.4 days). The time taken for the fracture to heal and functional outcomes were comparable among the two groups.

CONCLUSIONS

The CS technique demonstrated lower complications, in particular, no CS patient had implant removals, wire migration or fracture displacement. Additionally, CS technique showed a faster return to ambulation and time to achieving full weight bearing status.

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.

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.

Evolution in the Management of Patella Fractures

Patella fractures usually occur as a result of direct trauma to the anterior knee joint, indirect injury as a result of eccentric muscle contraction, or rapid knee flexion against a contracted quadriceps muscle. The patella functions as part of the extensor mechanism of the knee, where large forces are transmitted, and its subcutaneous nature has made treatment of patella fractures a challenge. In this review article, we evaluate how the management of these fractures has evolved over time and the advantages associated with the various treatment techniques. There are few comparative studies looking at the different treatment types for fractures of the patella, with the goal of achieving a functional extensor mechanism with low rates of post-traumatic arthritis and metal-work irritation.

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.

Observation of the effect of arthroscopically assisted percutaneous minimally invasive Kirschner wire tension band fixation on the treatment of patellar fractures

BACKGROUND

Patellar fractures are common intra-articular fractures. Arthroscopically assisted reduction and fixation has been shown to advantageous in the treatment of patellar fractures.

OBJECTIVE

This study aimed to investigate the effect of arthroscopically assisted percutaneous minimally invasive Kirschner wire tension band fixation on the treatment of patellar fractures.

METHODS

Thirty-four patients with acute closed patellar fractures enrolled in the study and were managed by arthroscopically assisted percutaneous minimally invasive Kirschner wire tension band fixation under epidural anesthesia. Among these patients, 24 were males, and ten were females. The mean age of these patients was 38 ± 0.8 years (range: 25-62 years). Of these patients, 20 had transverse fractures, five had longitudinal fractures, four had marginal oblique fractures, and five had multifragmentary upper and lower pole. Fracture causes: 25 were caused by falls, and nine were caused by traffic accidents. The time from injury to operation was 6-48 hours, with an average of 23 hours. The average post-operative follow-up was 12.8 months, and at the end of follow-up, the Boestman scoring system was used to evaluate knee joint function.

RESULTS

All the wounds healed by first intention, and no infections, skin necrosis, joint stiffness, or other complications occurred. Three months after operation, the tension band wire had broken in one patient, but the fracture had united, and this did not affect the prognosis. In eight patients, the average circumference at 10 cm above the patella was 0.6 cm less on the injured side than on the contralateral side. The average Boestman score was 27.5. The final result was excellent in 25 patients, good in eight patients, and acceptable in one patient.

CONCLUSION

Arthroscopic management of simple patellar fracture with percutaneous minimally invasive Kirschner wire tension band fixation is less invasive than open operation, while still leading to firm fixation, and is conducive to early functional training and functional recovery, and thus is an effective method of management for patellar fractures.

[Patalla Fractures]

Patella fractures are rare injuries, accounting for 0.5 - 1.5% of all fractures, but they can lead to severe functional limitations if they do not heal properly. In addition to a prompt diagnosis, surgical treatment is usually necessary for multi-fragment fractures. The goals of every treatment are a biomechanically stable joint as well as a congruent restoration of the retropatellar joint surface. These results often remain a challenge, especially in multiple fragment fractures. The surgical treatment strategies have steadily evolved from tension band and screw osteosyntheses in combination with wire cerclages. Currently, angular stable plate systems are increasingly being used. This article gives an overview of the fracture anatomy, the classification and diagnosis of patella fractures and the currently used surgical treatment options.

Risk factors and new inflammatory indicators of deep vein thrombosis after adult patella fractures

OBJECTIVE

This study aimed to investigate the association between new inflammatory indicators at admission and the occurrence of preoperative deep vein thrombosis (DVT) in patients with patella fractures.

METHODS

A retrospective analysis of the medical records of patients aged 18 years or older who underwent surgical treatment for unilateral closed patella fractures at our hospital between August 2016 and August 2020. The incidence of preoperative DVT was detected by Duplex ultrasound (DUS). Partial blood routine and biochemical indexes were collected at admission, and the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) of inflammatory indexes were also calculated. ROC was used to analyze the cut-off value NLR, MLR, and PLR for predicting preoperative DVT, and univariate and multivariate analyses of the risk factors for preoperative DVT of patella fractures, and to verify whether other risk factors affecting the relationship between validation indexes and preoperative DVT.

RESULTS

A total of 500 patients were included, of which 39 patients (7.8%) developed preoperative DVT. After univariate and multivariate analysis, preoperative time (in each day delay), male (vs. female), D-dimer > 0.6 mg/L, total cholesterol (TC) > 5.6 mmol/L, and PLR > 189.8 were the risk factors for preoperative DVT in patients with patella fracture. Inflammation index PLR combined with the other four risk factors significantly improved the predictive efficacy of preoperative DVT compared with PLR (P = 0.009).

CONCLUSION

Inflammatory index PLR is a risk factor for preoperative DVT in patients with patella fracture, and the efficacy of PLR in predicting DVT can be significantly improved when other risk factors (male, D-dimer > 0.6 mg/L, TC > 5.6 mmol/L, and PLR > 189.8 of preoperative time in each day delay) are combined. These data are useful for the clinical identification of patients at high risk of preoperative DVT in patella fractures.

No difference in clinical and radiological outcomes following fixation of transverse patella fractures with either suture tape or metallic cerclage: A retrospective comparative study

INTRODUCTION

Several surgical techniques have been proposed for the treatment of patellar fractures. The aim of this study is to compare the clinical efficacy and complication rates of treatment using suture tape circumferential cerclage (STCC) and metallic wire circumferential cerclage (MWCC) for the surgical treatment of displaced transverse patellar fractures (TPFs).

HYPOTHESIS

The hypothesis is that the use of the suture tape would be associated with a significantly lower rate of re-operation than metallic cerclage but no differences in other clinical outcomes.

PATIENTS AND METHODS

A retrospective comparative analysis of the clinical outcomes of consecutive patients undergoing fixation of TPFs with either MWCC or STCC between January 2017 and December 2018 was undertaken. All patients underwent evaluation with standardised radiographs at one, three, and six months after surgery to determine rates of union, non-union, loss of fixation and malunion. All patients underwent a final clinical evaluation at 18 months postoperatively to evaluate clinical scores and complications.

RESULTS

A total of 26 patients were included in the study. Thirteen patients underwent STCC and 13 underwent MWCC. There were no complications in the STCC group. In the MWCC group, one patient underwent hardware removal at 2 months postoperatively due to painful prominence. There was no significant difference in re-operation rates between the STCC and MWCC groups (p=1). There were no cases of non-union, malunion or loss of fixation throughout the series. At the final clinical follow-up of 18months, there were no significant differences in KSS, KOOS or Böstman scores between the groups.

CONCLUSION

No significant differences were identified when comparing the clinical outcomes of fixation of AO/OTA 34C1/2 fractures with suture tape or metallic cerclage fixation concerning re-operation rates, union rates, loss of fixation and functional outcome measures. These results cannot be extrapolated to more complex injury patterns or surgical techniques in which prominence of implanted material is more likely.

LEVEL OF EVIDENCE

III.

Anterior Locking Plate Osteosynthesis of Patellar Factures - Analysis of Complications and Functional Outcome

BACKGROUND

Tension band wiring is the standard procedure for patellar fractures, but is associated with a high rate of implant related complications and implant failure. Tension band wiring may fail, especially with multifragmentary and comminuted fractures. Plate fixation of complex patellar fractures seems to be superior to wiring, both clinically and biomechanically. The aim of this study was to evaluate complications after locking plate fixation in patellar fractures two years after surgery and to access the functional outcome.

MATERIAL AND METHODS

As part of a prospective case series, all patients who had received locking plate fixation of a patellar fracture between April 2013 and May 2018 were clinically examined two years postoperatively and potential complications were evaluated.

RESULTS

A total of 38 patients aged 19 - 87 years were included. Complications occurred in a total of five patients (13%), including one reactive prepatellar bursitis, one chronic infection and loss of reduction due to a dislocated pole fragment in three cases. The average active range of motion of the affected knee joint two years postoperatively was 133°. The Tegner activity scale score reached 3 points, the Lysholm score 95 points and the Kujala score 95 points.

CONCLUSION

With an overall relatively low complication rate and good clinical outcome, dislocated distal pole fragments are a common complication after plate fixation of patellar fractures. If preoperative diagnostic testing shows a pole fragment, a modified hook-plate can be used, with the possibility of fixing the pole fragment.

A cortical screw based tension band construct for transverse patella fractures: An evolving strategy for addressing common modes of failure

INTRODUCTION

Displaced patella fractures represent a clinical challenge. We evaluate the effectiveness of an alternative fixation construct to address common modes of fixation failure.

METHODS

A retrospective review of 49 patients who underwent fixation via the specific construct at a single institution between 2013 and 2019.

RESULTS

Median follow-up was 52.7 weeks (Mean: 75.4 weeks; SD: 54.9; range: 27-267.7 weeks). Construct failure rate was 6.1% (3/49). This included two mechanical hardware failures, one the result of trauma and the other due to noncompliance.

CONCLUSIONS

The modified construct represents a safe and effective means of treating transverse patella fractures.

LEVEL OF EVIDENCE

Level 4.

The epidemiology of traumatic musculoskeletal injuries in Kuwait: Prevalence and associated risk factors

Objectives

Epidemiological explorations of traumatic injuries are essential to provide benchmarks for future planning to address multidimensional challenges. The study aimed to describe the epidemiology of traumatic musculoskeletal injuries in Kuwait, including their prevalence and associated risk factors.

Methods

The Orthopedic Admission Database of a level II trauma center in Kuwait was retrospectively reviewed from January 2018 to February 2020. Traumatic fractures of the spine and upper and lower limbs were explored.

Results

The study included 564 patients with 788 traumatic injuries who were 33.0 (23.0) years of age (median and interquartile range): 78.0% were male, and 43% were Kuwaitis. Spinal fractures were the most prevalent injury, at 21.7%, followed by tibial fractures, at 11.3%, and ankle fractures, at 10.2%. Road traffic accidents were the leading mechanism of injury, at 37.9%, followed by falling over and falling from height, at 29.3% and 16.8%, respectively. Risk factors included injury mechanism, nationality, and age (p < 0.05). Road traffic accidents were at risk for sustaining spinal, scapular, clavicle, humeral, pelvic, hip, tibial, and fibular fractures; those for falling over were radial, ulnar, femoral, and patellar fractures; and those for falling from height were foot and ankle fractures. Kuwaitis were found to be at risk of spinal, humeral, pelvic and femoral fractures, whereas non-Kuwaitis were found to be at risk of scapular, shoulder, elbow, ulnar, radial, hip, patellar, tibial, fibular, foot, and ankle fractures. The age range of 19–49 years was associated with the highest risk for all fracture sites.

Conclusion

Epidemiological characteristics of traumatic injuries in Kuwait have been determined to guide preventive strategies and healthcare planning.

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

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.

Outcome Analysis of Fixed Angle Locking Plate in Patella Fractures: A Single Centre Experience from North India

BACKGROUND

Tension band wiring supposedly is the most commonly used technique for displaced patella fractures, but is not effective in comminuted fractures and osteoporotic bones. It often leads to loosening of wires, dislocation of fracture, hardware problem and failure of osteosynthesis, resulting in knee stiffness and post-traumatic osteoarthritis. The aim of the study is to evaluate clinical outcome in patients with acute patella fractures (< 3 week) treated with unidirectional angle fixed low-profile titanium patella locking plate.

MATERIALS AND METHODS

Twenty patients who presented with displaced patella fractures, aged between 18-70 years were included in the study. All fractures were reduced and fixed with unidirectional angle fixed stable low-profile titanium patella locking plate. Knee Range of motion and Knee Outcome Survey Activities of Daily Living Scale (KOS-ADL) was used to evaluate the outcome.

RESULTS

We were able to achieve union in 19 out of 20 patients. One patient with comminuted patella fracture had failure of fixation, which was revised. Mean flexion at final follow-up was 124° (110°-130°) and none of the patients had extensor lag. The final radiograph revealed complete union in all patients.

CONCLUSION

This technique offers an option of fixation in comminuted patella fracture and in osteoporotic individuals. It provides mechanical stability for fracture fixation resulting in anatomical reduction, good functional outcome, lower incidence of symptomatic implant or failure of osteosynthesis.

[Current treatment standard for patella fractures in Germany]

BACKGROUND

The treatment of patella fractures is technically demanding. Although the radiological results are mostly satisfactory, this often does not correspond to the subjective assessment of the patients. The classical treatment with tension band wiring with K‑wires has several complications. Fixed-angle plate osteosynthesis seems to be biomechanically advantageous.

OBJECTIVE

Who is treating patella fractures in Germany? What is the current standard of treatment? Have modern forms of osteosynthesis become established? What are the most important complications?

MATERIAL AND METHODS

The members of the German Society for Orthopedics and Trauma Surgery and the German Knee Society were asked to participate in an online survey.

RESULTS

A total of 511 completed questionnaires were evaluated. Most of the respondents are specialized in trauma surgery (51.5%), have many years of professional experience and work in trauma centers. Of the surgeons 50% treat ≤5 patella fractures annually. In almost 40% of the cases preoperative imaging is supplemented by computed tomography. The classical tension band wiring with K‑wires is still the preferred form of osteosynthesis for all types of fractures (transverse fractures 52%, comminuted fractures 40%). In the case of comminuted fractures 30% of the surgeons choose fixed-angle plate osteosynthesis. If the inferior pole is involved a McLaughlin cerclage is used for additional protection in 60% of the cases.

DISCUSSION

The standard of care for patella fractures in Germany largely corresponds to the updated S2e guidelines. Tension band wiring is still the treatment of choice. Further (long-term) clinical studies are needed to verify the advantages of fixed-angle plates.

[Patellar fractures]

Patellar fractures are a relatively rare entity with an prevalence of 1%. Preoperative computed tomography has gained a significant role as a diagnostic tool for patellar fractures in recent years. It enables an exact assessment of the fracture and helps in the decision making for the correct treatment procedure. Therapeutically, the armamentarium was supplemented by angle stable plate fixation, which potentially enables a better reconstruction of the patella than the conventional tension band fixation. In this context, the results of angle stable plate fixation are promising in terms of functional outcome and lower complication rates. The proven tension band fixation using K‑wires or cannulated screws continues to be widespread in clinical practice and retains significance for simple patellar fractures. The use of polyethylene thread material instead of steel wire has shown advantages in biomechanical studies but the clinical application is more restrained.

[Fractures of the patella]

With 1% of all skeletal fractures patellar fractures are rare. The majority of cases are caused by a direct trauma to the flexed knee. The diagnosis is made via the injury mechanism as well as the physical and radiological findings. In conventional x‑ray imaging the extent of injury often is underrated, which mostly leads to the necessity of a computed tomography (CT) scan. The aim of the treatment is the reconstruction of the extensor mechanism and the anatomical reconstruction of the articular surface. The type of treatment depends on the fracture type. Tension band wiring still is the most frequently practiced technique. Complications, such as secondary dislocation or migration of the K‑wires resulting in revision surgery have been described in up to 30% of the cases. Studies could already show a higher biomechanical stability of osteosynthesis via cannulated screws. Especially in cases of comminuted fractures, osteosynthesis via a locking plate seems to have several advantages but long-term results are not yet available.

Comparison of SCAphoid fracture osteosynthesis by MAGnesium-based headless Herbert screws with titanium Herbert screws: protocol for the randomized controlled SCAMAG clinical trial

Background

Scaphoid fractures are the most common carpal fractures. They often need to be treated by surgery, where the use of a compression screw is the globally accepted gold standard. Surgeons may choose between different implant materials including titanium alloys, which remain in the body or are removed after healing. An alternative are biodegradable magnesium-based implants. Properties of magnesium alloys include high stability, osteoconductivity, potential reduction of infections and few artifacts in magnetic resonance imaging (MRI). The aim of this trial is to demonstrate non-inferiority of magnesium-based compression screws compared with titanium Herbert screws for scaphoid fractures.

Methods

The trial is designed as a multicenter, blinded observer, randomized controlled parallel two-group post market trial. Approximately 190 patients will be randomized (1:1) with stratification by center either to titanium or magnesium-based compression screws. Follow-up is 1 year per patient. Surgical procedures and aftercare will be performed according to the German treatment guideline for scaphoid fractures. The first primary endpoint is the patient-rated wrist evaluation (PRWE) score after 6 months. The second primary endpoint is a composite safety endpoint including bone union until 6 months, no adverse device effect (ADE) during surgery or wound healing and no serious ADE or reoperation within 1 year. The third primary endpoint is the difference in change MRI artifacts over time. Non-inferiority will be investigated for primary endpoints 1 (t-test confidence interval) and 2 (Wilson’s score interval) using both the full analysis set (FAS) and the per protocol population at the one-sided 2.5% test-level. Superiority of magnesium over titanium screws will be established using the FAS at the two-sided 5% test-level (Welch test) only if non-inferiority has been established for both primary endpoints. Secondary endpoints include quality of life.

Discussion

This study will inform care providers whether biodegradable magnesium-based implants are non-inferior to standard titanium Herbert screws for the treatment of scaphoid fractures in terms of wrist function and safety. Furthermore, superiority of magnesium-based implants may be demonstrated using MRI, which is used as surrogate endpoint for screw degradation.

Trial registration

DRKS, DRKS00013368. Registered Dec 04, 2017.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2723-9) contains supplementary material, which is available to authorized users.

Outcomes after locked plating of displaced patella fractures: a prospective case series

PURPOSE

Tension band wiring remains a common treatment for patella fractures, but complication rates are high, with unsatisfactory results. The purpose of this observation study was to evaluate clinical results and complication rates of a novel patella locking plate fixation.

METHODS

Twenty patients (mean age, 59.2 ± 18 years) with displaced patella fractures were prospectively enrolled. Range of motion, knee scores (Tegner, Lysholm, Kujala), complications, and revision surgeries were assessed six weeks, six months, 12 months, and 24 months after surgery. Results were compared to the situation before trauma in regards to the time of follow-up using a paired sample t test.

RESULTS

According to the OTA classification, the fractures were classified as follows: one A1, four C1, six C2, and nine C3. Range of motion improved from 121° after six weeks to 140°, 141°, and 143° within the follow-up period. While the Tegner, Lysholm, and Kujala scores were 4.1/97/97, respectively, before trauma, they improved from 2.6/80/89 to 3.6/94/89, 3.7/95/94, and 4.1/97/97 within the follow-up period. Three patients had a complication (15%): one fracture dislocation, one reactive bursitis, and one renewed fracture. Four patients reported discomfort or anterior knee pain especially when kneeling on the implant.

CONCLUSIONS

The patella locking plate is a safe and effective treatment for patella fractures, including comminuted fractures. Function can be restored within six months after surgery, and the complication rate is low. Nonetheless, the implant can cause discomfort or anterior knee pain especially when kneeling, which can necessitate an implant removal.

[Plate osteosynthesis after patellar fracture - the technique and initial results of a prospective study]

BACKGROUND

Tension band wiring after patellar fractures is related to a high number of implant-related complications (22-53 %). Revision surgery is necessary in 10-55 % of patients mostly with unsatisfactory results. The patella plate is an alternative treatment with the advantages of locked plating. The purpose of this study was to evaluate the first clinical prospective results and complications of this new implant.

MATERIALS AND METHODS

Between April 2013 and May 2015 all patients that were treated with locked plating for patella fractures were included in this prospective study. Patients were followed-up clinically after six weeks and six months.

RESULTS

Included in this study were 17 patients, 6 women and 11 men, with a mean age of 58 years (19-87). The knee range of motion was 120° after 6 weeks and improved to 138° after 6 months, corresponding to 84 % and 97 % of the range of motion of the healthy opposite knee. The Tegner activity scale increased from 2,5 to 3,5 (initial value: 4), the Lysholm score increased from 78 to 92 points (initial value: 97) and the Kujala score increased from 72 to 88 points (initial value: 96). Two complications occurred: one patient had a reactive bursitis prepatellaris and one patient sustained a loss of reduction.

CONCLUSION

Locked plating of patella fractures is a reliable alternative treatment with good functional outcomes and low complication rates.

Treating patella fractures with a locking patella plate - first clinical results

The standard treatment for patella fractures is tension band wiring. However, with tension band wiring anatomical reduction and rigid fixation can be challenging and the clinical outcome after patella fracture is often not satisfying. The purpose of this prospective clinical observation was to evaluate the clinical outcome in patients with patella fractures treated with an angular stable patella plate. Between 2011 and 2015 a total of 67 patients were treated with an angular stable patella plate. Outcome in these patients was evaluated by the Knee Outcome Survey Activities of Daily Living Scale (KOS-ADL) and range of motion of the knee joint was assessed. Complete follow up was obtained for 35 patients. In these patients, we found one implant-related complication. None of the patients reported any deficits in extension capabilities. The flexion was on average 127° (SD 21°). The patients classified the function of their knee in daily life on average with 77% (SD 24%) in comparison to their function before the trauma. Only kneeling or squatting was a problem in some patients. In conclusion, angular stable patella plating appears to be a promising alternative treatment for patella fractures. The patella plate provides increased mechanical stability for fracture fixation which appeared to result in a reduction of complications and improvement of functional outcome compared to tension band wiring. Especially patients with a multi-part or comminuted fracture or with osteoporotic bone are likely to benefit from the stability provided by the plate and the locking screws.

[A finite element analysis of petal-shaped poly-axial locking plate fixation in treatment of Y-shaped patellar fracture]

Objective

To establish the finite element model of Y-shaped patellar fracture fixed with titanium-alloy petal-shaped poly-axial locking plate and to implement the finite element mechanical analysis.

Methods

The three-dimensional model was created by software Mimics 19.0, Rhino 5.0, and 3-Matic 11.0. The finite element analysis was implemented by ANSYS Workbench 16.0 to calculate the Von-Mises stress and displacement. Before calculated, the upper and lower poles of the patella were constrained. The 2.0, 3.5, and 4.4 MPa compressive stresses were applied to the 1/3 patellofemoral joint surface of the lower, middle, and upper part of the patella respectively, and to simulated the force upon patella when knee flexion of 20, 45, and 90°.

Results

The number of nodes and elements of the finite element model obtained was 456 839 and 245 449, respectively. The max value of Von-Mises stress of all the three conditions simulated was 151.48 MPa under condition simulating the knee flexion of 90°, which was lower than the yield strength value of the titanium-alloy and patella. The max total displacement value was 0.092 8 mm under condition simulating knee flexion of 45°, which was acceptable according to clinical criterion. The stress concentrated around the non-vertical fracture line and near the area where the screws were sparse.

Conclusion

The titanium-alloy petal-shaped poly-axial locking plate have enough biomechanical stiffness to fix the Y-shaped patellar fracture, but the result need to be proved in future.

[Plate osteosynthesis of patellar fractures]

OBJECTIVE

Anatomic reconstruction of the retropatellar articular surface and repair of the extensor mechanism of the knee joint. The osteosynthesis should allow immediate mobilization as part of an early functional postoperative rehabilitation protocol.

INDICATIONS

Displaced fractures of the patella, especially multifragment and comminuted fractures with a retropatellar incongruity or dislocation of >2 mm.

CONTRAINDICATIONS

Critical local soft tissue because of the risk of postoperative infection.

SURGICAL TECHNIQUE

Median skin incision. For simple (transverse) fractures, preservation of the soft tissue and reduction control via the index finger. For complex fractures, lateral arthrotomy and eversion of the patella. Reconstruction of the articular surface from the joint side with optimal visibility. Temporary fixation with Kirschner wires, osteosynthesis with the fixed angle plate. If necessary, additional screws or wires.

POSTOPERATIVE MANAGEMENT

Immediate mobilization with full weightbearing in full extension with a knee brace. Extension/flexion 0/0/60° for 4 weeks, then 0/0/90° until the 7th week. Active extension after 6 weeks. Climbing stairs after 12 weeks.

RESULTS

Good functional results in combination with a low rate of complications and revisions.

Treatment of comminuted patellar fracture with the nitinol patellar concentrator

AIM

To evaluate the clinical effect of the nitinol (NiTi)-patellar concentrator (NT-PC) for the treatment of comminuted patellar fractures.

MATERIAL AND METHODS

A total of 32 patients with acute comminuted patellar fracture accepted open reduction and internal fixation with the NT-PC, and the curative effects were evaluated using the Böstman clinical grading scale.

RESULTS

All fractures were anatomically reduced by surgery and all cases were followed-up for six to 18 months. The mean score of patients according to the Böstman clinical grading scale was 25.6, with 29 of 32 (90.7%) patients achieving excellent or good results. Two patients had traumatic arthritis, one had slippage of the NT-PC, and all patients received pharmacotherapy.

CONCLUSIONS

The application of the NT-PC is a satisfactory approach to the treatment of comminuted patellar fractures.

Current concepts review: Fractures of the patella

Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration.

For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined – due to its biomechanical superiority – with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment.

Comparison of Tension-Band Wiring With the Cable Pin System in Patella Fractures: A Randomized Prospective Study

OBJECTIVES

To compare the outcome of tension-band wiring (TBW) with the cable pin system (CPS) for transverse fractures of the patella.

DESIGN

Randomized prospective study.

SETTING

Academic Level I trauma center.

PATIENTS/PARTICIPANTS

From February 2008 to December 2011, 73 consecutive patients with transverse fractures of the patella were prospectively enrolled in this study.

INTERVENTION

The patients were randomly divided into 2 groups: one group was treated using the CPS, and the other group was treated using the modified TBW.

MAIN OUTCOME MEASUREMENTS

The clinical outcome assessment included analyses of the radiographic images, the modified Hospital for Special Surgery scoring system, and complications.

RESULTS

The follow-up time ranged from 12 to 29 months. All fractures healed, with a union rate of 100%. The fracture healing time was significantly shorter in the CPS group (8.51 ± 2.59 weeks, n = 34) compared with the TBW group (11.79 ± 3.04 weeks, n = 39). Postoperative complications in the CPS and TBW groups were observed in 1 and 9 patients, respectively, a difference that was statistically significant. The mean Hospital for Special Surgery score for the CPS group (90.53 ± 5.19 points) was significantly higher than that for the TBW group (81.36 ± 12.71 points).

CONCLUSIONS

The CPS is a viable option for transverse fractures of the patella and is associated with a shorter healing time, fewer complications, and better function than TBW.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical Assessment of Locked Plating for the Fixation of Patella Fractures

OBJECTIVE

To analyze the mechanical stability of locked plating in comparison with tension-band wiring for the fixation of fractures of the patella.

METHODS

Biomechanical tests were performed on artificial foam patella specimens comparing an angular stable plate and monocortical screws with tension-band wiring. Tests were performed under combined tension and bending until failure simulating physiological loading of the tibia during walking.

RESULTS

Tension-band wiring failed at 66% of the failure load of plating (1052 N, P = 0.002) and had 5 times larger fracture gap displacements (P = 0.002).

CONCLUSIONS

Based on the biomechanical advantages, locked plating of the patella may constitute a reasonable alternative in the treatment of patella fractures.

[Classification and treatment of patella fractures]

Patella fractures are rare and account for approximately 1% of all fractures. They are classified regarding their localization (proximal, distal) and appearance. The aim of any treatment is reconstruction of the extensor mechanism and joint surface. If dislocation and cartilage steps are less than 2 mm, conservative treatment may be indicated. Operative treatment is only necessary if a dislocation is more than 2 mm or when the extensor mechanism is unstable. Depending on the shape of the fracture, tension band wiring, interfragmentary screw fixation and combinations are the main techniques. Because patellectomy has functionally the worst result it should be avoided. Sleeve fractures (children) need exact reconstruction of the joint surface. In elderly patients conservative treatment or surgical patella-enclosing wiring techniques for stabilization are the best options due to low bone quality.