Cyclic long-term loading of a bilateral fixed-angle plate in comparison with tension band wiring with K-wires or cannulated screws in transverse patella fractures

Does protruding headless cannulated screw reduce fixation stability in tension band wiring technique for patella fractures? a biomechanical study

BACKGROUND

The selection of an implant is a critical factor in the surgical treatment of patella fractures due to the risk of various complications, such as non-union, implant failure, and irritation. The present study evaluated and compared the biomechanical strength of headless cannulated screws about screw length using the tension band wiring technique.

METHODS

Forty-eight sawbone patellas with transverse fractures were divided into three fixation groups based on the screw length used in tension band wiring. Overall, three different fixation groups were determined: Group 1 (recessed headless cannulated screw fixation), Group 2 (full-length headless cannulated screw fixation), and Group 3 (protruding headless cannulated screw fixation). A setup was used to simulate a knee with a flexion angle of 60 degrees. Specimens underwent biomechanical testing under axial traction (static test) and cyclic loading (dynamic test). Displacements at 300 Newtons (N), loads at 2 millimetres (mm) displacement, and failure loads were documented for each sample in the static test. In the dynamic test protocol, 10,000 repetitive cycles were performed under physiological load between 100 and 300 N, and final displacements were recorded.

RESULTS

There were significant differences in the loads achieved at 2 mm displacement levels, and Group 3 demonstrated lower force values compared to other constructs in the static test (P = 0.003). All groups revealed similar displacements at 300 N and failure load values under axial traction. In the dynamic test, Group 3 had significantly higher fracture displacement under cyclic loading compared to the other specimens (P = 0.006).

CONCLUSIONS

This study found headless cannulated screws for transverse patella fracture fixation provide sufficient stability; however, protruding headless screws reduce the fixation strength. Recessed or full-length screws may improve stability and bony healing, potentially preventing complications in patella fractures.

LEVEL OF EVIDENCE

Biomechanical study N/A.

Return to play and performance after patellar fracture in American professional sports: a case-control cohort analysis

OBJECTIVES

This study describes the effects of patellar fracture on return to play (RTP) and functional outcomes among athletes in American professional sports.

METHODS

Professional athletes from the National Football League (NFL), National Basketball Association (NBA), Major League Baseball (MLB), and National Hockey League (NHL) who suffered a patellar fracture between January 1965 and December 2021 were identified through injury reports and public archives. Performance scores, play time, and games played were collected for the season preceding patellar fracture and 2 seasons after RTP, and differences in recorded metrics compared to pre-injury levels and matched controls were analyzed.

RESULTS

Twenty-nine of 41 (71%) injured athletes returned to play at an average of 217 days. Among all players, play volume decreased in year 1 compared to baseline but recovered to pre-injury levels in year 2. Athletes treated operatively experienced an initial decline in performance (p < 0.01) but recovered to pre-injury performance level in year 2. Nonoperative management resulted in a decline in performance in year 2 of RTP (p = 0.02). Athletes treated operatively performed significantly worse than matched controls in year 1 of RTP (64% vs. 99%; p = 0.04) but recovered to a similar level of performance as controls in year 2 (87% vs. 91%; p = 0.90).

CONCLUSION

A 71% rate of RTP was demonstrated among this limited cohort of 29 athletes in American professional sports after isolated patellar fracture. Although details regarding fracture characteristics and operative reports were not available for analysis, operative management was not associated with longer absence from play compared to nonoperative treatment. Despite the limitations of this study, the findings suggesting operative management may improve prospects of maintaining elite performance following RTP warrant further investigation.

LEVEL OF EVIDENCE

Case-control cohort analysis; Level of evidence, 3.

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.

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

OBJECTIVES

To evaluate radiographic and clinical patient-reported outcomes following dorsal hook plating of displaced patella fractures with permittance of immediate postoperative active closed chain range of motion.

METHODS

DESIGN

Retrospective review of prospectively collected data.

SETTING

Urban academic level 1 trauma center.

PATIENT SELECTION CRITERIA

Adult patients with displaced patella fractures (OTA/AO 34C1-3) who underwent dorsal plating with immediate range of motion between 2018 and 2023.

OUTCOME MEASURES AND COMPARISONS

Numerical Rating Scale for Pain, Knee Outcome Score (KOS-ADL), Tegner-Lysholm score, radiographic union, and wound complications were collected.

RESULTS

Sixty-one patients were included (47 female) with an average age of 63 years (SD 14.7, range 22-86 years). The mean BMI was 24.2 (SD 3.6, range 16.6-33.3). There were 13 34-C2 and 48 34-C3 fractures. All but 2 patients (96.7%) achieved bony union after the index procedure. 89% (n = 54) of patients completed outcome surveys with at least 6-month follow-up. Six patients (9.8%) underwent removal of plate implant at a mean of 15.1 months postoperatively. The mean KOS-ADL score was 91.4, the mean Tegner-Lysholm score was 78.1, and the mean NRS was 2.7.

CONCLUSIONS

Dorsal hook plating offers secure fixation to allow early range of motion, reliable fixation with low nonunion and implant failure rates, low implant removal rates, and satisfactory patient-reported outcomes.

LEVEL OF EVIDENCE

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

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.

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.

Incidence of postoperative complications in patellar fractures related to different methods of osteosynthesis procedures - a retrospective cohort study

BACKGROUND

Patellar fractures have a comparatively low incidence compared to all fracture frequencies of the musculoskeletal system. However, surgical management is crucial to prevent postoperative complications that affect the knee joint. The purpose of the present study was to evaluate the incidence of postoperative complications and onset of postoperative osteoarthritis related to the chosen technique of patellar fracture management.

METHODS

In a retrospective cohort study consecutive managed, isolated patella fractures were reviewed for demographic data, trauma mechanism, patella fracture type, fixation technique and postoperative complications. The results were documented radiographically and clinically and analysed statistically. The reporting followed the STROBE guidelines.

RESULTS

A total of 112 patients were eligible for data evaluation. Surgical management of comminuted patellar fractures with small fragment screws showed significant fewer postoperative complications compared to other fixation techniques (8%, p < 0.043). The incidence of posttraumatic infection was significantly higher following the hybrid fixation technique with cannulated screws and tension wire than following the other analysed techniques (p = 0.024). No postoperative wound infection was observed after screw fixation or locking plate fixation. Symptomatic hardware was most frequently seen after tension-band fixation. Onset of posttraumatic osteoarthritis was most often found after the hybrid fixation technique (55%).

CONCLUSION

Surgical management of patellar fractures remains crucial but fracture fixation using plating systems or small fragment screws is least associated with postoperative complications.

TRIAL REGISTRATION

Trial registration number (DRKS):00027894.

Effect of Physiotherapy on a Rare Case of Malunion of Femur and Patellar Fracture in a 43-Year-Old Male: A Case Report

The hip is a ball-and-socket joint surrounded by strong and well-balanced muscles that allow for a wide range of motion in many physical planes. Iliofemoral, ischiofemoral, and pubofemoral are the three major ligaments of the hip joint that provide stability to the joint. Supracondylar femoral fractures are common in old age and can be caused in young people due to accidents or traumatic causes. These types of fractures are complicated to fix surgically due to different architectural designs. If not treated appropriately, these can cause malunion or non-union of the joint. The knee joint is a synovial joint of the hinge type. It has two major degrees of movement, which are flexion and extension. However, rotation in both the medial and lateral directions is possible to some extent in the joint. Patellar fractures can be transverse, vertical, comminuted, marginal, or osteochondral. In this case report, we present a 43-year-old male patient who had a history of falling from a bike. He was diagnosed with a comminuted supracondylar fracture of the left femur and a comminuted fracture of the patella on the left side on an X-ray. For this, he was managed with open reduction, internal fixation, and vacuum-assisted closure (VAC). Physiotherapy rehabilitation was programmed to attain a good and fast recovery for the patient to make him functionally independent and improve his quality of life.

Patella Fracture Fixation With Novel Wagon Wheel Construct Versus Tension-Band Construct: A Technical Trick

SUMMARY

Internal fixation of patella fractures remains technically challenging. Cannulated screws with an anterior tension band have been associated with high rates of implant prominence, and fracture comminution can make appropriate application of a tension band impractical. We present the results of a novel technique using a transtendinous/transligamentous mini-fragment plate positioned peripherally around the patella with radially directed screws: termed the wagon-wheel (WW) construct. Compared with a cohort of fractures treated with cannulated screws with an anterior tension band, there was no difference in final range of motion and rate of nonunion. The WW construct had a significantly decreased incidence of symptomatic implants (5% vs. 32%, P = 0.02), rate of reoperation (9% vs. 38%, P = 0.018), dependency on gait aids (10% vs. 38%, P = 0.031), and a faster time to union (HR: 2.2; 95% CI, 1.28-3.95, P = 0.005). In summary, the WW was designed with the goal of obtaining peripheral plate fixation to maximize fragment-specific fixation while minimizing implant prominence. Patients treated with the WW demonstrated reduced rates of implant prominence and reoperation.

Novel screw-cable integrated system(SCIS) for minimally invasive treatment of patella transverse fractures: a finite element analysis

BACKGROUND

The most recommended method for treating transverse patella fractures is modified tension band wiring (MTBW). However, the optimal instrument for use with MTBW is still undetermined. Hence, we aimed to design a novel screw-cable integrated system (SCIS) and compare its biomechanical characteristics with Kirschner-wire, SCIS, and Cable-Pin systems in treating transverse patellar fracture.

METHODS

A finite-element (FE) model of transverse patella fracture was created. The fracture model was fixed with either K-wire, SCIS, or Cable-pin. Different tension force loading (400 N and 800 N), direction(0° and 45°), and screw or K-wire depth(5 mm and 10 mm) were set. The maximum displacement of the fragment and maximum gap opening were measured by using FE analysis.

RESULTS

Compared with the K-wire and Cable-pin system, SCIS increased the stability of the fractured patella by reducing fragment displacement and gap opening. Under 400 N loading in the direction 45°, SCIS with screw placing at 5-mm depth reduced the maximum fragment displacement (0.43 mm) by 49.62% and 26%, respectively, compared with the K-wire (0.22 mm) and Cable-pin (0. 22 mm) group. Meanwhile, the gap opening in SCIS (0.05 mm) was reduced by 83% and 59.8% (0.05 to 0.18) compared with the K-wire (0.30 mm) and Cable-pin (0.18 mm) group.

CONCLUSION

SCIS demonstrated improved biomechanical stability for treating transverse patellar fractures compared to MTBW with Kirschner wire and the Cable-Pin system. Finite element analysis showed SCIS substantially reduced fracture fragment displacement and gap opening under various loading conditions.

Tension-band wiring through a single cannulated screw combined with suture anchors to treat inferior pole fracture of the patella

PURPOSE

To evaluate the feasibility and clinical outcomes of tension-band wiring through a single cannulated screw combined with two suture anchors in treating inferior pole fracture of the patella.

METHODS

Between September 2018 and September 2021, a total of 22 patients with a mean age of 55 years who sustained inferior pole fracture of the patella and were treated by tension-band wiring through a single cannulated screw combined with two suture anchors were enrolled. X-ray radiographs were performed to observe the bone union time. The duration of each operation was recorded to reflect the complexity of surgical treatment. Functional measurements, comprising range of motion (ROM), the Böstman scale, and the Knee Injury and Osteoarthritis Outcome Score (KOOS), were taken. Postoperative complications including fixation failure, incision infection, loss of reduction, and malunion were evaluated.

RESULTS

All patients were followed up for an average of 17 months (range: 12-25 months). The average clinical bone union time was 8 weeks (range: 6-12 weeks), and the radiographic bone union time was 11 weeks (range: 8-12 weeks). At the final follow-up, the mean ROM was 136° (range: 115°-140°), the KOOS was 85 (range: 68-100) and the Böstman score was 28 (range: 20-30); these outcomes were classified as excellent in 17 cases and good in 5 cases, with no instances of poor results. Loss of reduction occurred in one case, while no cases of incision infection, fixation failure or malunion were observed.

CONCLUSION

For inferior pole fracture of the patella, tension-band wiring through a single cannulated screw combined with suture anchors can offer sufficient fixation stability to achieve a satisfactory clinical outcome with reduced operational complexity; this procedure should be recommended in clinical practice.

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.

[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.

Combination of Cable Cerclage and Hook Plate for the Fixation of Comminuted Fractures of Inferior Patellar Pole: A Review of 16 Consecutive Patients Followed Up for a Minimum of 1 Year

Objectives

To present a new method consisting of cable cerclage and hook plate for fixating the comminuted inferior patellar pole fracture and evaluate the outcomes.

Methods

A total of 16 consecutive patients who were treated with the construct of a cable cerclage in combination with a hook plate between January 2018 and September 2020 were included in the study. Mechanism of injury, duration, and technical details of the operation were reviewed. Plain radiographs and computerized tomography (CT) scans were routinely taken to evaluate the fracture pattern. The primary outcome measures included bony healing time, pain intensity‐numerical rating scale (PI‐NRS), range of motion (ROM), and the Bostman score at the final follow‐up.

Results

Eight males and eight females with an average age of 55.6 ± 12.0 years (range, 41 to 73 years) were included. Bony union was achieved in all the patients, with an average healing time of 10.8 ± 2.4 weeks (range, 8–16 weeks). With the average follow‐up of 20.1 ± 5.3 months, 12 patients (75%) had no pain (PI‐NRS score of 0), and the remaining four patients (25%) reported mild pain (three with a PI‐NRS score of 1 and one with a score of 2). The final Bostman score was 27.8 ± 3.0 (range, 20–30) on average, and all the patients showed excellent or good results. The average range of motion was 127.5° ± 13.9° (range, 90°–140°). No implant failure or hardware irritation was found during the follow‐up.

Conclusion

The fixation of cable cerclage combined with hook plate resulted as a reliable method for managing the inferior patellar pole fractures, allowing immediate rehabilitation and weight‐bearing.

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.

Suture tension band fixation vs. metallic tension band wiring for patella fractures - A biomechanical study on 19 human cadaveric patellae

PURPOSE

Traditional tension band fixation of patella fracture is associated with high reoperation rates. The purpose of the study was to assess strength of fixation in patella fractures treated with either a non-metallic all suture-based technique or traditional metallic tension band wiring.

METHODS

Ten paired human cadaveric specimens were included. A transverse fracture was created, reduced and fixated with a non-metallic or metallic approach. Non-metallic fixation was done according to a previously published technique, metallic fixation was done according to AO description. Specimens were fixed in 90° of flexion and underwent 200 cycles of loading by pulling the Quadriceps tendon to 300 Newton. Fracture displacement was optically monitored. Primary outcome was fracture displacement after 200 cycles compared to the first cycle. Subsequently, load-to-failure was assessed by a monotonic pull to 1000 N.

RESULTS

For cyclic loading analysis, one specimen from each group was excluded due to machine synchronization, resulting in a total population of 18 specimens. Median (min-max) fracture displacement was 0.65 mm (0.06-1.3) in the non-metallic group and 0.68 mm (0-1.23), (p=0.931) in the metallic group. No difference in displacement was found between the two groups in the repeated measures analysis of variance (p=0.5524). For load-to-failure analysis one specimen was excluded due to machine synchronization, resulting a total population of 19 specimens. 2/9 specimens failed in the non-metallic group (at 979 and 635 N) and 2/10 failed in the metallic group (745 and 654 N).

CONCLUSION

Non-metallic technique is a biomechanically viable alternative to traditional tension band fixation and it can hopefully lead to fewer implant-related complications.

A New Antirotation Strategy of K-Wire Tension Band Therapy for Patellar Fracture

Background

Patellar fracture is a common phenomenon observed in orthopedic clinics. Many methods have been shown to be effective in the fixation of patellar fracture. However, there are few studies on the antirotation effect of these methods. The purpose of this study is to present a new strategy of K-wire tension band therapy for patellar fracture and explore the antirotation effect of the modified tension band method on patellar fracture.

Methods

A retrospective clinical observation study was conducted on 75 patients with patellar fracture. Totally, 46 patients were enrolled to the traditional group, who received the traditional K-wire tension band therapy. The modified group included 29 patients on whom our new strategy was implemented. The operation time, intraoperative blood loss, and fracture healing time were collected to compare the two operations and the knee society score (KSS) scores after the operations, and complications were recorded and retrieved to indicate the effectiveness of the two treatments.

Results

The preoperative baseline data (gender, age, fracture types) of the two groups showed no significant statistical difference. Similarly, there was no significant difference in the operation time, intraoperative blood loss, and fracture healing time between the two groups. The KSS clinical scores 1 year after operation was 90 (84, 95) for the traditional group as compared with 99 (97, 100) for the modified group (p < 0.05). The KSS functional scores 1 year after operation in the two groups were 90 (65, 90) and 100 (90, 100) (p < 0.05). The incidences of complications due to the rotation of K-wires in the traditional group and the modified group were 76.1% (35 of 46) and 6.9% (2 of 29) with a significant statistical difference (p < 0.05).

Conclusion

This study shows that our modified tension band therapy is an effective strategy for antirotation in the treatment of patellar fracture and proves that it can achieve better clinical outcomes than the traditional K-wire tension band method. This new strategy may be a safe and effective clinical technique for the treatment of patellar fracture. However, more prospective randomized controlled trials with larger sample sizes are still needed to further prove its efficacy.

A Modified Tension Band Fixation Technique for the Management of Patellar Fractures Using Crossed Pins and a Lateral Parapatellar Approach

The use of the tension band technique for patellar fracture fixation has been associated with a loss of the rigidity of the construct after cyclic loading. Biomechanical studies have shown the biomechanical superiority of the crossed pin configuration relative to the traditional parallel one. Here, we describe a modified tension band technique that involves the use of crossed pins and a figure-of-eight passed as close to the bone as possible through a lateral parapatellar approach. The basic surgical technique and our case series are reviewed.

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.

Patellar Fractures: Anatomy, Mechanics, and Surgical Management

➤ A preoperative computed tomography scan may be considered to improve surgical planning, as secondary fracture lines are poorly visualized on radiographs.➤ Oblique internal and external rotation fluoroscopic views may be used intraoperatively to fully evaluate the medial and lateral facet articular reduction if direct assessment by visualization or palpation is not completed.➤ Partial patellectomy for inferior pole fractures should be avoided, and bone-preserving procedures are recommended.➤ A lateral arthrotomy may be used for direct visualization of the articular reduction for multifragmentary fractures. An inferomedial arthrotomy should be avoided to protect the dominant blood supply of the patella.➤ Tension band fixation with cannulated screws yields a lower reoperation rate, improved functional outcome scores, and better performance in biomechanical studies than Kirschner wire-based tension band fixation.➤ Preliminary studies of novel plate and screw constructs for osteosynthesis have shown promising results.

Suturing methods in prolapse surgery: a biomechanical analysis

INTRODUCTION

Pelvic organ prolapse is a common problem in urogynecological surgery. Abdominal and laparoscopic sacrocolpopexy is currently considered to be the gold standard of treatment. The main problem remains the anatomical point of fixation as well as how sutures are placed. We evaluated the biomechanical difference between an in-line ligament suture versus an orthogonal ligament suture and a single suture versus a continuous suture at the anterior longitudinal ligament in an in-vitro, sacrocolpopexy model.

METHODS

Biomechanical in-vitro testing was performed on human, non-embalmed, female cadaver pelvises. An Instron test frame (tensinometer) was used for load/ displacement analysis. The average patient age was 75 years. Ligament preparation yielded 15 ligaments available for testing. Recorded parameters were the ultimate load, failure displacement, and stiffness.

RESULTS

This in-vitro analysis of different suturing methods showed the difference between an orthogonal and an in-line approach to be the ultimate load. Orthogonal sutures displayed an ultimate load of 80 N while in-line suturing yielded only 57 N (p < 0.05). For the anterior longitudinal ligament, this study demonstrated that continuous suture is significantly superior to a single suture regarding failure displacement (p < 0.05).

CONCLUSION

We established baseline biomechanical parameters for the sacrospinous ligament and anterior longitudinal ligament. An orthogonal suture is superior to an in-line suture in an in-vitro model. A continuous suture is superior to a single suture at the anterior longitudinal ligament. Clinical trials might be able to evaluate whether any clinical significance can be established from these findings.

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.

Patella fracture fixation with a non-locked anterior plating technique: A biomechanical study

OBJECTIVES

The purpose of this study was to compare the biomechanical attributes of patella fracture fixation with either anterior plating utilizing two parallel, longitudinal 2.0 mm plates technique versus a cannulated screw tension band technique.

METHODS

Five matched pairs (ten specimens) of fresh frozen cadavers were utilized. A transverse patella fracture (OTA 34C1.1) was fixed using either two 4.0 mm cannulated screw anterior tension band (CATB) or with two 2.0 mm stainless steel non-locking plates along the anterior cortex secured with 2.4 mm cortical screws traversing the fracture site. Specimens underwent 1000 cycles of simulated active knee range of motion before load to failure destructive testing.

RESULTS

During cyclic loading there were no failures in the plate fixation group, and 2 out of 5 specimens catastrophically failed in the CATB group (p = 0.22). Average fracture displacement at the end of fatigue testing was 0.96 mm in the plate fixation group and 2.72 mm in the CATB group (p = 0.18). The specimens that withstood cyclic testing underwent a destructive load. Mean load to failure for the plate fixation specimens was 1286 N, which was not significantly different from the CATB group mean of 1175 N (p = 0.48). The mechanism of failure in the plate fixation cohort was uniformly via a secondary vertical patella fracture around the plates in all five specimens. In the CATB group, the mechanism of failure was via wire elongation and backing out of the screws.

CONCLUSIONS

Patella fixation with anterior plating technique statistically performed equivalent to cannulated screw anterior tension band in ultimate load to failure strength and fatigue endurance under cyclical loading. No failures were observed cyclic simulated active range of motion in the anterior plate group. There was a trend towards improved fatigue endurance in the plate fixation group, however this did not reach statistical significance. We believe plate fixation technique represents a low-profile implant option for treatment of transverse patella fractures, which may allow for early active range of motion, and these data support biomechanical equivalency to standard of care.

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.

Biomechanical comparison of a 3.5 mm anterior locking plate to cannulated screws with anterior tension band wiring in comminuted patellar fractures

PURPOSE

To date, surgically treated multifragmentary patellar fractures are still associated with high rates of complications, such as i.e. secondary fracture displacement. Osteosynthesis is most frequently performed with screws and cerclages. To increase primary stability, locking plates have been introduced. However, there is still a lack of biomechanical data supporting the superiority of plate fixation compared to screw fixation with cerclages in these cases. The goal of the present study was to conduct biomechanical comparison of these two techniques under dynamic loading conditions.

METHODS

A standardized 34-C3 fracture was created in eight pairs of human cadaveric knee joints. Following a randomization protocol, they were fixed with a 3.5 mm anterior locking plate (LP) or cannulated screws with anterior tension band wiring (hybrid osteosynthesis, HO).Subsequently, all constructs were tested for 100 cycles from 90° of knee-flexion to full extension by applying a pulling force to the quadriceps tendon. Outcome parameters were fracture displacement after one cycle, after 100 cycles and implant loosening. Failure was defined as fracture displacement > 2 mm.

RESULTS

Biomechanical testing showed significantly less fracture displacement following LP compared to HO both after the first (p = 0.042) and after 100 cycles (p = 0.025). The difference in loosening was significant as well (p = 0.017). Following HO, 5/8 constructs failed during cyclic loading. There was no failure in the LP group. In the HO group, loosening correlated with bone mineral density (R = - 0.857) which was not observed in the LP group (R = - 0.429).

CONCLUSION

Anterior locking plate osteosynthesis of comminuted patellar fractures biomechanically provides better primary stability compared to cannulated screws with anterior tension band wiring.

Modified two-tension-band for patellar fractures

Objective

To compare a modified two-tension-band (MTTB) technique with the AO tension band in treating patellar fractures.

Methods

This retrospective study included patients treated with AO tension band (group 1) or MTTB (group 2). Data obtained during serial follow-up evaluations of time to bony union, range of motion (ROM), Hospital for Special Surgery (HSS) score and complication rates, were analysed.

Results

Fractures healed in all 51 patients included in the study (group 1, n = 28; group 2, n = 23), with no statistically significant between-group difference in time to bony union. Regarding function results, group 2 had better HSS scores at 3 and 6 months postoperatively; however, at 1 year postoperatively, both groups had similar HSS scores and achieved acceptable flexion and ROM. The overall complication rate was significantly lower in group 2, but average costs were higher in group 2 versus group 1.

Conclusion

MTTB provides secure fixation and improved knee function at 3 and 6 months postoperatively, and has a lower complication rate with early mobilization, compared with the AO tension-band technique.

Role of screw proximity in the fixation of transverse patellar fractures with screws and a wire

PURPOSE

Clinical and biomechanical studies have reported that using supportive screws and a wire instead of the common Kirschner wires for modified tension band wiring improves the stability of fractured patellae. However, the effect of screw proximity on the fixation of a fractured patella remains unclear. Therefore a numerical study was conducted to examine the effects of screw proximity on biomechanical responses in a simulated patellar fracture fixed using two parallel cannulated screws and anterior tension band wiring.

METHODS

A patellar model with a transverse fracture and loads simulating patellar tendon forces applied on the patella were used in the present simulation. The surgical fixation consisted of two 4.0-mm parallel partially threaded cannulated screws with a figure-of-eight tension band made using a 1.25-mm stainless steel wire. Biomechanical responses at two screw proximities, 5 and 10 mm from the leading edge of the patella, were investigated.

RESULTS

Superficial screw placement (5 mm) yielded higher stability, lower wire loads, and lower bone contact pressures than the deep placement (10 mm). The deep placement of screws exerted a higher load on the wire but a lower force on the screw than superficial placement did.

CONCLUSION

This is the first numerical study to examine the effects of screw location on the fixation of a fractured patella using cannulated screws and tension band wiring. Considering the favorable biomechanical responses, superficial placement (5 mm below the leading edge of the patella) is recommended for screw insertion when treating a transverse fractured patella.

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.

Laparoscopic pectopexy: a follow-up cyclic biomechanical analysis determining time to functional stability

INTRODUCTION

Pectopexy, a laparoscopic method for prolapse surgery, showed promising results in previous transient testing by this group. It was shown that a single suture, yielding an ultimate load of 35 N, was equivalent to continuous suturing. This was demonstrated in an in vitro cadaver study. This transient data were used to establish an elastic stress-strain envelope. It was now possible to proceed to dynamic in vitro analysis of this surgical method to establish time to functional stability.

METHODS

Cyclic testing of this fixation method was performed on human female embalmed cadaver (cohort 1) and fresh, non-embalmed cadaver (cohort 2) pelvises. The testing envelope was 5-25 N at a speed of 1 mm/s. 100 load regulated cycles were applied.

RESULTS

100 cycles were completed with each model; no overall system failure occurred. Steady state, i.e., functional stability was reached after 14.5 (± 2.9) cycles for the embalmed group and after 19.1 (± 7.2) cycles for the non-embalmed group. This difference was statistically significant p = 0.00025.

CONCLUSION

This trial showed in an in vitro cyclic testing of the pectopexy method that functional stability may be achieved after no more than 19.1 cycles of load exposure. When remaining within the established load envelope of below 25 N, patients do not need to fear global fixation failure. Testing did demonstrate differences in non-embalmed and embalmed cadaver testing. Embalmed cadaver testing tends to underestimate time to steady state by 26.3%.

Roles of the screw types, proximity and anterior band wiring in the surgical fixation of transverse patellar fractures: a finite element investigation

BACKGROUND

Cannulated screws with an anterior wire are currently used for managing transverse patellar fracture. However, the addition of anterior wiring with various types of screws via open surgery to increase the mechanical stability is yet to be determined. Hence, this study aimed to compare the mechanical behaviors of a fractured patella fixed with various screws types and at various screw locations with and without the anterior wire. The present study hypothesized that using the anterior wire reduces the fracture gap formation.

METHODS

A finite element (FE) model containing a fractured patella fixed with various types of cannulated screws and anterior wiring was created in this study. Three types of screws, namely partial thread, full thread, and headless compression screws, and two screw depths, namely 5 and 10 mm away from the anterior surface of the patella, were included. The effect of the anterior wire was clarified by comparing the results of surgical fixation with and without the wire. Two magnitudes and two loading directions were used to simulate and examine the mechanical responses of the fractured patella with various fixation conditions during knee flexion/extension.

RESULTS

Compared with partial thread and headless compression screws, the full thread screw increased the stability of the fractured patella by reducing fragment displacement, fracture gap formation, and contact pressure while increasing the contact area at the fracture site. Under 400-N in the direction 45°, the full thread screw with 5-mm placement reduced the gap formation by 86.7% (from 2.71 to 0.36 mm) and 55.6% (from 0. 81 to 0. 36 mm) compared with the partial thread screw with 10-mm placement, respectively without and with the anterior wire.

CONCLUSION

The anterior wire along with the full thread screw is preferentially recommended for maintaining the surgical fixation of the fractured patella. Without the use of anterior wiring, the full thread screw with 5-mm placement may be considered as a less invasive alternative; however, simple screw fixation at a deeper placement (10 mm) is least recommended for the fixation of transverse patellar fracture.

[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.

Treatment of Patella Fractures

Patella fractures comprise 1% of all fractures. Treatment options vary based on fracture displacement, classification, and patient factors. Traditionally, nonoperative treatment has been reserved for nondisplaced fractures. Many operative treatments are available with differing indications and levels of success. Tension band constructs have been the most commonly employed approach to fixation, with cerclage wiring for comminuted fractures. Recently, plate fixation of patella fractures has become more popular. Plating constructs offer a low-profile design with stable fixation, allowing for earlier mobilization and potentially improved functional outcomes. Data regarding the long-term outcomes of plating techniques are limited, and further studies are needed. [Orthopedics. 2018; 41(6):e747-e755.].

Failure of Patellar Plating with Mini-Fragment Implants: A Case Report

CASE

A 40-year-old woman presented to the emergency department with a comminuted fracture of the patella with separation of the bone fragments. The patient underwent an open reduction and osteosynthesis using medial and lateral 2.0-mm nonlocking plates, which subsequently led to pain in the anterior and posterior aspects of the knee.

CONCLUSION

In this patient, bicolumnar nonlocking plating was unable to adequately resist the tensile forces of the extensor mechanism. We believe that the probable cause of failure was an insufficient neutralization of the tensile forces exerted by the extensor mechanism. Because of the substantial forces acting on the patella, a method of converting these tensile forces into compressive forces is very beneficial, as seen with anterior tension-band wiring. Although we used nonlocking plates in our patient, we believe that locking-plate fixation placed along the medial and lateral columns also would have had a biomechanical disadvantage in dispersing the tensile forces exerted by the extensor mechanism.

A novel technique of using a miniature plate in combination with tension band wiring to treat comminuted patellar fractures

Traditionally, tension band fixation has been used for treating simple fracture patterns; however, fixation remains a challenge, especially for comminuted fractures. We describe a new method of operation using a combination of a miniature plate with tension band wiring to treat comminuted patellar fractures. The aim of this technique is to transform complicate fractures into simple transverse fractures. As far as we know, no studies using a similar method have been found.The purpose of this study was to assess the effectiveness of a novel technique in which a miniature plate is used in combination with tension band wiring to treat comminuted patellar fractures.Between March 2013 and May 2015, 16 patients with closed, displaced, comminuted fractures of the patella were included in the present study. All subjects underwent fixation using a combination of a miniature plate with a tension band wire. Knee function and patient status were evaluated at 12 months using the Böstman knee score and Lysholm knee scale.The average follow-up period was 15.6 months (range, 12-20 months). At the 12-month follow-up, bone healing was satisfactory in all patients. The average postoperative Lysholm score was 91.6 ± 1.4 (range, 84-97). The average postoperative Böstman scale score was 26.4 ± 0.5 (range, 22-30), thereby indicating excellent results in 4 patients and good results in 12. No patients required reoperation.The results demonstrate that this new technique is an effective and safe treatment option for comminuted patella fractures, as it is associated with good clinical outcomes.

Biomechanical comparison of pin and tension-band wire fixation with a prototype locking plate fixation in a transverse canine patellar fracture model

Objective: To compare a locking plate (LP) with pin and tension-band wire (pin/TBW) for fixation of mid-patellar transverse fractures.

Materials and methods: Cadaveric canine stifle joints from 10 adult mixed breed dogs (23–36 kg) were used. Mid-patellar transverse osteotomies were randomly stabilized (in pairs) with either pin/TBW or a prototype LP. Cyclic loads (1 Hz, 500 cycles) at 100% body weight (90°-135° stifle joint extension), were applied. Survival or failure of constructs was defined as <2 mm fracture gap distraction at 500 cycles, or ≥ 2 mm fracture gap distraction at the number of cycles sustained, respectively. Number of cycles at failure and distraction gap were compared with a paired Student’s t-test, and a survival analysis performed with a Mantel-Cox test. All constructs that survived cyclic testing were tested in single cycle load to failure (1.0 mm/sec; 110° stifle joint extension); yield strength was compared with a Wilcoxon rank sum test. Significance was set at p <0.05.

Results: All 10/10 LP and three out of 10 pin/ TBW fixations survived cyclic testing. Survival analysis, number of cycles at failure, and distraction gap all were significantly different between the two groups (p = 0.0011, p = 0.0013, and p <0.0001, respectively). Construct yield strength was not significantly different (p = 0.1273).

Conclusions: The failure mode with pin/TBW was consistently similar to failures observed clinically. The LP demonstrated consistent, reliable and stable fixation.

This work was performed at the Biomechanics Orthopedic Research Laboratory, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA, USA.

Functional outcome and economic burden of operative management of patellar fractures: the pivotal role of onerous implants

OBJECTIVES

The complication rate following operative treatment of patellar fractures remains high and is associated with a poor functional outcome. The primary goal of this study was to evaluate our functional outcome of patellar fracture osteosynthesis and define strategies to improve the outcome. The healthcare costs and utilization were calculated.

METHODS

All demographic, clinical, radiographic variables and hospital-related costs of 111 patients with 113 surgically treated patellar fractures between January 2005 and December 2014 were analyzed. Fractures were grouped as either simple or complex. Functional outcome was assessed using Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

There were 67 simple fractures (59.3%) and 46 complex fractures (40.7%). The overall complication rate was 48.7%, including 19.5% implant-related complications. In 69 patients (61.1%), implants were removed. The outcome was rather poor, with considerable impairment in all KOOS subscales with the knee-related quality of life rated worst (median 62.5, IQR 37.5-81.25). Poor outcome correlated significantly with complex patellar fractures and extensive tension-band constructs.

CONCLUSIONS

The operative treatment of patellar fractures was associated with a high complication rate, functional impairment and reduced quality of life. Complex patellar fractures and extensive tension-band constructs were identified as the main determinants of poor outcome and increased economic burden due to higher reinterventions rates. Strategies to reduce complications and improve outcome should focus on less onerous implants.

Superior Outcomes After Operative Fixation of Patella Fractures Using a Novel Plating Technique: A Prospective Cohort Study

OBJECTIVE

The purpose of this prospective cohort study was to determine if a new patella fracture fixation construct resulted in improved outcomes compared with traditional tension band techniques.

DESIGN

Comparative cohort study.

SETTING

Academic level I trauma center.

PATIENTS/PARTICIPANTS

Patients with isolated, unilateral patellar fractures were enrolled prospectively. From 2012 to 2014, 33 patients underwent fixation with a novel plate construct that spans half of the patella circumference laterally and provides multiplanar fixation through a low-profile plate. A comparison cohort was drawn from 25 patients treated from 2008 to 2012, where treatment consisted of traditional tension band fixation techniques.

INTERVENTION

Surgical fixation of patella fractures was performed with either a tension band or novel plate construct.

MAIN OUTCOME MEASUREMENTS

Subjective postoperative clinical outcomes and objective functional and strength measurements were subsequently collected.

RESULTS

The 2 cohorts had similar baseline characteristics. Patients with the plate construct had clinically and statistically significantly superior Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS) scores throughout the study period (P < 0.001). Functional testing also demonstrated significant improvements in patients with plate constructs compared with tension band constructs at 12 months. Patients in the plate cohort had significantly increased thigh circumferences (P = 0.003) and decreased anterior knee pain (P < 0.0001) compared with the tension band cohort.

CONCLUSIONS

In this prospective cohort study, the use of a novel fixation construct with multiplanar and interfragmentary fixation and minimal disruption of patellar vascularity enables improved clinical outcomes and functional performance.

LEVEL OF EVIDENCE

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

Inframammary Fold Reconstruction: A Biomechanical Analysis

Background:

Inframammary fold reconstruction has scarcely been evaluated in literature. No biomechanical analyses have been performed comparing different reconstructive methods. This evaluation compares the gold-standard suture reconstruction with an intrarib anchor system (Micro BioComposite SutureTak, Arthrex).

Methods:

Three analysis groups were compared including 8 Sawbone blocks, 22 embalmed cadaver, and 27 regular cadaver specimens (N = 57). Transient mechanical analysis was performed at 5 N/s using an Instron 5565 test frame.

Results:

Ultimate load favored the anchor system (compared with the gold-standard suture) by a factor of 9.8 (P < 0.0001) for the regular cadaver group and a factor of 1.7 (P < 0.038) for the embalmed cadaver group. A similar statistically significant benefit was shown for stiffness and load at 2-mm displacement.

Conclusions:

This analysis showed an anchor system to be the biomechanically superior fixation method in terms of ultimate load, fixation stiffness, and displacement at failure when compared with the gold-standard suture method in inframammary fold reconstruction. Because of superior stability in every aspect, an anchor system may be considered for inframammary fold reconstruction.

Laparoscopic Pectopexy: A Biomechanical Analysis

Introduction

Pectopexy, a laparoscopic method for prolapse surgery, showed promising results in recent literature. Further improving this approach by reducing surgical time may decrease complication rates and patient morbidity. Since laparoscopic suturing is a time consuming task, we propose a single suture /mesh ileo-pectineal ligament fixation as opposed to the commonly used continues approach.

Methods

Evaluation was performed on human non-embalmed, fresh cadaver pelves. A total of 33 trials was performed. Eight female pelves with an average age of 75, were used. This resulted in 16 available ligaments. Recorded parameters were ultimate load, displacement at failure and stiffness.

Results

The ultimate load for the mesh + simplified single “interrupted” suture (MIS) group was 35 (± 12) N and 48 (± 7) N for the mesh + continuous suture (MCS) group. There was no significant difference in the ultimate load between both groups (p> 0.05). This was also true for displacement at failure measured at 37 (± 12) mm and 36 (±5) mm respectively. There was also no significant difference in stiffness and failure modes.

Conclusion

Given the data above we must conclude that a continuous suture is not necessary in laparoscopic mesh / ileo-pectineal ligament fixation during pectopexy. Ultimate load and displacement at failure results clearly indicate that a single suture is not inferior to a continuous approach. The use of two single sutures may improve ligamental fixation. However, overall stability should not benefit since the surgical mesh remains the limiting factor.

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.

Multiplanar Fixation for Patella Fractures Using a Low-Profile Mesh Plate

Patella fractures are challenging orthopaedic injuries. Many commonly used fixation techniques can be ineffective and lead to poor clinical outcomes even with satisfactory reductions and fracture healing. In this investigation, we present the technique of cage plate fixation of patella fractures and the clinical outcomes of 9 initial patients surgically treated at our institution. This technique allows direct visualization of the articular reduction, provides multiplanar fixation, effectively stabilizes inferior pole comminution, and reduces the risk of patella vascular disruption. Using this technique, we have achieved excellent functional and radiographic outcomes.

Femoral fixation strength following soft-tissue posterolateral corner reconstruction using fibular-based technique: Biomechanical analysis of four techniques in normal and low-density synthetic bone

BACKGROUND

Optimal femoral fixation of soft-tissue grafts has been described for anterior cruciate ligament reconstruction. Posterolateral corner reconstruction differs from ACL reconstruction in two ways: (a) soft-tissue fixation into the femur requires two tails and (b) the line of force is different. Our purpose was to determine the optimal femoral fixation of soft-tissue grafts during posterolateral corner reconstructions. We hypothesized that interference screw fixation is the strongest technique in normal-density lateral femoral condyle, whereas, cortically-based fixation techniques are stronger methods in low-density lateral femoral condyle.

METHODS

We evaluated elongation during cyclic loading, yield load, peak load-to-failure, and stiffness of four soft-tissue graft femoral fixation methods during posterolateral corner reconstruction. Our model included bovine flexor tendons and contoured synthetic bones. Grafts were secured to the lateral epicondyle in normal- or low-density bone models using spiked washer, button, interference screw, or button and interference screw. Five specimens for each were tested in each bone density. Analysis of variance using Tukey-Kramer adjustment for multiple hypothesis testing was used. Six cadaver bones whose density was analyzed using computerized tomography scan quantitation were tested using interference screw fixation.

RESULTS

No method produced significantly stronger yield load or peak load-to-failure in normal-density bone. In low-density bone, cortically-based methods produced significantly higher yield load or peak load-to-failure. Yield load or peak load-to-failure was significantly higher in normal-density bone when using spiked washer or interference screw fixation.

CONCLUSION

No femoral fixation method tested produced superior yield load or peak load-to-failure. Spiked washer and interference screw fixation are inferior fixation methods in low-density bone.

CLINICAL RELEVANCE

For fibular-based posterolateral corner reconstructions, all fixation methods tested are acceptable in high-density bone, while cortical fixation methods should be considered in low-density bone.

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.

Plating of patella fractures: techniques and outcomes

Operative treatment of displaced patella fractures with tension band fixation remains the gold standard, but is associated with a significant rate of complications and symptomatic implants. Despite the evolution of tension band fixation to include cannulated screws, surprisingly little other development has been made to improve overall patient outcomes. In this article, we present the techniques and outcomes of patella plating for displaced patella fractures and patella nonunions.

Fixation of multifragmentary patella fractures using a bilateral fixed-angle plate

This biomechanical study is the first to compare 3 fixation methods-bilateral fixed-angle plate, modified anterior tension wiring, and cannulated lag screws with anterior tension wiring-in multifragmentary distal patella fractures. A T-shaped 3-part fracture simulating a multifragmentary articular distal patella fracture (AO/OTA 34-C2.2) was created in 18 human cadaver knee specimens. Three groups were created using homogenous ages and bone mineral densities based on the fixation method received. Repetitive testing over 100 cycles was performed by moving the knee against gravity from 90° flexion to full extension. Failure was defined as fracture displacement greater than 2 mm. In all patellae using fixed-angle plates, an anatomical fracture reduction could be maintained throughout cyclic testing, whereas anterior tension wiring and lag screws with tension wiring showed significant fracture displacement after 100 cycles, with mean fracture gaps of 2.0±1.3 and 1.9±1.6 mm, respectively. The differences in fracture gaps between the fixed-angle plate group and the other 2 groups were statistically significant. In both groups using tension wiring, half of the constructs (3 of 6 in each group) failed due to a fracture displacement greater than 2 mm. The bilateral fixed-angle plate was the only fixation method that sustainably stabilized a multifragmentary articular distal patella fracture during cyclic loading when compared with modified anterior tension wiring and cannulated lag screws with anterior tension wiring.

Pullout strength of bone-patellar tendon-bone allograft bone plugs: a comparison of cadaver tibia and rigid polyurethane foam

PURPOSE

To compare the load-to-failure pullout strength of bone-patellar tendon-bone (BPTB) allografts in human cadaver tibias and rigid polyurethane foam blocks.

METHODS

Twenty BPTB allografts were trimmed creating 25 mm × 10 mm × 10 mm tibial plugs. Ten-millimeter tunnels were drilled in 10 human cadaver tibias and 10 rigid polyurethane foam blocks. The BPTB anterior cruciate ligament allografts were inserted into these tunnels and secured with metal interference screws, with placement of 10 of each type in each material. After preloading (10 N), cyclic loading (500 cycles, 10 to 150 N at 200 mm/min) and load-to-failure testing (200 mm/min) were performed. The endpoints were ultimate failure load, cyclic loading elongation, and failure mode.

RESULTS

No difference in ultimate failure load existed between grafts inserted into rigid polyurethane foam blocks (705 N) and those in cadaver tibias (669 N) (P = .69). The mean rigid polyurethane foam block elongation (0.211 mm) was less than that in tibial bone (0.470 mm) (P = .038), with a smaller standard deviation (0.07 mm for foam) than tibial bone (0.34 mm).

CONCLUSIONS

All BPTB grafts successfully completed 500 cycles. The rigid polyurethane foam block showed less variation in test results than human cadaver tibias.

CLINICAL RELEVANCE

Rigid polyurethane foam blocks provide an acceptable substitute for human cadaver bone tibia for biomechanical testing of BPTB allografts and offer near-equivalent results.