Cannulated Screw Prominence in Tension Band Wiring of Patella Fractures Increases Fracture Gapping: A Cadaver Study

Morphological characteristics and a new classification system of the inferior pole fracture of the patella: A computer-tomography-based study

PURPOSE

The objective of this study was to measure the morphological characteristics of inferior pole fracture of the patella (IPFP) and develop a practical classification system to determine the corresponding treatment protocols for different IPFPs with specific patterns.

METHODS

A retrospective radiographic review was performed on a series of 71 patients with IPFP. The preoperative CT data were collected and measured using image processing software. The number of fragments, maximum fracture fragment anteroposterior length (MFFAL), maximum fracture fragment transverse length (MFFTL), fracture fragment coronal angle (FFCA), fracture fragment sagittal angle (FFSA), maximum fracture fragment height (MFFH) and maximum transverse sectional area (MTSA) were analysed.

RESULTS

The mean number of fracture fragments was 3.8. The average MFFAL was 14.9 mm, the average MFFTL was 23.5 mm, the average FFCA was 92.1°, the average FFSA was 93.0°, the average MFFH was 13.6 mm, and the average MTSA was 299.3 mm2. A new classification system was introduced to describe the varied patterns of IPFP, summarized as (I) simple IPFP; (II) comminuted IPFP; (III) simple IPFP with simple patellar body fracture; and (IV) comminuted patellar fracture involving the inferior pole. With the four-type classification system, 12 type I, 22 type II, 21 type III, and 16 type IV lesions were observed, each with specific morphological characteristics.

CONCLUSION

Most IPFPs exhibited a diversiform pattern, demonstrating that coverage fixation was likely needed. The four-type classification system might offer a valuable approach to help orthopaedic surgeons make individual treatment plans.

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.

Transosseous suture versus suture anchor fixation for inferior pole fractures of the patella in osteoporotic bone: a biomechanical study

BACKGROUND

The surgical treatment of inferior patellar pole fractures can be a challenge, especially in geriatric patients, who are particularly frequently affected by osteoporosis. The objective of this biomechanical study was to compare the performance of suture anchor and transosseous suture fixation in fractures of the inferior patellar pole in context of bone mineral density.

METHODS

Twelve fresh-frozen human cadaveric knees received a transverse osteotomy, simulating an AO/OTA 34C1.3 inferior pole fracture of the patella. These fractures were fixated with either suture anchors (SA; Corkscrew^® FT 4.5 mm) or transosseous suture (TS; #2 FiberWire^®). Cyclic loading tests were performed by pulling the quadriceps tendon against gravity from 90° flexion to almost full extension (5°) for 1000 cycles. Motion and fracture gap displacement were tracked until failure occurred. Subsequently, loading to failure tests followed. Differences between groups were compared using unpaired t-tests, and correlations were calculated with Pearson's correlation coefficient.

RESULTS

The suture anchor group showed significantly fewer cycles to failure than the transosseous suture group (SA: 539.0 ± 465.6 cycles, TS: 1000 ± 0 cycles, P = 0.04). Bone mineral density correlated positively with cycles to failure in the suture anchor group (Pearson's r = 0.60, P = 0.02). No differences in fracture gap displacement could be proven after 100 cycles (SA: 4.1 ± 2.6 mm, TS: 6.5 ± 2.6 mm, P = 0.19); 500 cycles (SA: 6.4 ± 6.1 mm, TS: 9.6 ± 3.8 mm, P = 0.39); and 1000 cycles (SA: 4.0 ± 0.4 mm, TS: 11.0 ± 4.5 mm, P = 0.08). Furthermore, the mean destructive load to failure in the suture anchor group was also significantly lower than in the transosseous suture group (SA: 422.4 ± 212.2 N, TS: 825.7 ± 189.3 N, P = 0.04).

CONCLUSIONS

Suture anchors may be a viable alternative to transosseous suture in younger patients for clinical advantages, but in osteoporotic bone, the more stable osteosynthesis with transosseous suture continues to prove superior. Therefore, trauma surgeons might consider the use of transosseous suture in elderly patients, especially in those presenting with low bone mineral density values.

A minimally invasive bipolar surgical approach for the treatment of patellar fracture using the tension-band wiring technique

Objective

Minimally invasive surgical techniques are becoming increasingly popular for the treatment of traumatic injuries. Although some minimally invasive techniques in the management of patellar fractures have been reported, the limited exposure in such methods may cause technical difficulties during surgery and restrict their wide application. In this context, this study aims to introduce a bipolar incision and assess the clinical outcomes of patellar fractures treated via this type of incision.

Materials and methods

Patients who suffered patellar fractures and who received surgical treatment via bipolar incision between 2018 and 2020 in our hospital were retrospectively reviewed and included in this study. The clinical and radiological records of all patients were reviewed. A classification of the fractures was done and intraoperative parameters, Visual Analog Scale (VAS) score, knee range of motion, and the Hospital for Special Surgery (HSS) knee score of the patients were evaluated and summarized.

Results

The study included 19 patients who met the inclusion criteria. All patellar fractures were operated through the minimally invasive bipolar surgical approach. The mean time of operation was 69.0 ± 8.5 min. The mean time to union was 12.8 ± 2.1 weeks. The average total knee range of motion was 131.8 ± 4.4°, and the average HSS score was 97.1 ± 2.6 at 1-year post-operation. No surgical-related complications were observed.

Conclusions

The knee functional outcomes were favorable when patellar fractures were treated through the minimally invasive bipolar incision method. This bipolar surgical approach was found to be a feasible method for treating patellar fractures.

"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.

Comparison of Functional and Radiological Outcomes of Transverse Patellar Fractures Fixed with Tension Band Fixation Using Cannulated Screws and Kirschner Wires: A Prospective Randomized Study

PURPOSE

To compare functional and radiological outcomes of transverse patella fractures treated with tension band wiring using either two 4.5 mm cannulated screws or Kirshner wire.

METHODS

This is a non-blinded prospective randomized study comprising of two groups (n = 30 each) with closed transverse patella fractures treated with tension band wiring using Kirschner wire (K wire group) and two 4.5 mm cannulated screws (CCS group). Outcomes measured were radiological union, Knee Society score, range of motion and post-operative complications.

RESULTS

The CCS group showed a statistically significant higher range of motion than K wire group for each follow up (p < 0.001 in flexion and p < 0.005 in extension). A statistically significant higher percentage of patients in the CCS group showed signs of union at 6th and 12th post-operative week (p = 0.001 and 0.011 respectively) but no difference at 24th post-operative week (p = 0.313). The rate of hardware complications was significantly higher in K wire group (p = 0.001). No significant difference was noted in in the Knee society score and post-operative complications between the groups.

CONCLUSION

This study concludes that the fixation of closed transverse patella fractures using two 4.5 mm cannulated screws is allows a faster rate of union, a better knee range of motion and lesser hardware complications as compared to Kirschner wires. However more studies with larger sample sizes and longer follow up are required.

Patella Fractures: Approach to Treatment

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

[Effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in treatment of inferior patellar pole avulsion fractures]

Objective

To explore the method and effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in the treatment of inferior patellar pole avulsion fractures.

Methods

Betweern January 2015 and January 2019, 22 patients with inferior patellar pole avulsion fractures were admitted and treated. There were 12 males and 10 females. The age ranged from 20 to 69 years, with an average age of 39.4 years. The causes of injury included 9 cases of traffic accident and 13 cases of falling. All of them were unilateral closed injury of knee joint, including 7 cases of skin contusion around patella. Preoperative range of motion of the affected knee was (20.82±7.16)° (range, 10°-35°). The time from injury to operation ranged from 3 to 12 days, with an average of 5.9 days. During the operation, the inferior patellar avulsion fracture was reduced with forceps; the patella was circumferentially ligated through the distal bone surface of the fracture with 0.8 mm diameter steel wire; then 3 longitudinal bone tunnels were made in the upper patella, respectively. The 0.8 mm diameter steel wire passed through the bone tunnel, and the longitudinal ring was attached to the ring to fix the upper and inferior patellar fracture. Tighten the transverse and longitudinal rings with No.2 tendon suture line, then longitudinally ringed and sutured to strengthen the patella. The knee range of motion, fracture healing time, and complications were recorded. The functional recovery of the knee joint was evaluated by Böstman score.

Results

All incisions healed by first intention, and no incision related complications occurred. All the 22 patients were followed up 13 months to 5 years with an average of 26.7 months. The fracture healing time was 9-12 weeks (mean, 10.9 weeks). At last follow-up, the knee range of motion was (129.77±2.35)° (range, 126°-135°), showing significant difference when compared with preoperative one ( t=-67.022, P=0.000). The Böstman score ranged from 31 to 36, with an average of 34.3. No reduction loss, fracture of steel wire, failure of internal fixation, and other complications occurred during follow-up.

Conclusion

Multidirectionally three-dimensional steel wire ring sleeve fixation in the treatment of inferior patellar pole avulsion fractures has the advantages of reliable fixation, early functional recovery, and fewer complications, so the effectiveness is satisfactory.

Combination of a miniplate with tension band wiring for inferior patellar pole avulsion fractures

BACKGROUND

The tension-band technique, with Kirschner wires or cannulated screws, is one of the most commonly used fixation techniques for patellar fractures. However, it may be not useful for inferior patellar pole fractures as it may lead to fragment reduction loss and fixation failure. We present a surgical technique that combines a miniplate with tension band wiring for inferior patellar pole avulsion fractures and report surgical outcomes.

PATIENTS AND METHODS

Between June 2012 and May 2016, 17 consecutive patients (mean age: 51 years) with inferior patellar pole fractures (AO/OTA 34-A1) were treated operatively with a miniature plate in combination with tension band wiring. The final range of motion, bone union time, and Bostman score were the primary outcome measures.

RESULTS

The bone union time was 9.5 weeks on average after surgery (range: 8-12 weeks). No patient had loss of reduction or implant failure. There were no cases of irritation or other complications from the implant. At the final follow-up, the average range of motion arc was 128.24° (range: 105-140°). The mean Bostman score at the last follow-up was 28.1 points (range: 25-30 points). All patients showed excellent or good results 1 year after surgery.

CONCLUSION

The combination of a miniplate with tension band wiring for inferior patellar pole avulsion fractures provides stable flexion, allows for early range of motion, and provides excellent results in terms of knee function.