Biomechanical evaluation of current patella fracture fixation techniques

Anterior variable-angle locked plating of complex patella fractures - Does the type of polar screw matter?

BACKGROUND

Treatment of complex patella fractures represents a challenging clinical problem. Whereas controversy exists regarding the most appropriate fixation method, anterior plating is an emerging treatment option. A novel design of anterior variable-angle locking plates features radiating legs with integrated screw holes aiming at capturing fragments of the distal comminuted zone via either a locking or a cortical polar screw. The aim of this study was to compare the biomechanical performance of the novel anterior variable-angle locking plates used for fixation of complex patella fractures with either a locking or a cortical polar screw.

METHODS

Complex five-part AO/OTA 34-C3 patella fractures mimicking comminution around the distal pole were simulated in twelve human cadaveric knees. Specimens were randomized to two groups for treatment with an anterior variable-angle locking plate fixing the patella with either one locking or one cortical caudo-cranial bicortical polar screw. Biomechanical testing was performed over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive flexion within the range from 90° flexion to full extension. Interfragmentary movements were captured by motion tracking.

FINDINGS

No significant differences between the two fixation techniques were detected in terms of longitudinal and shear articular displacements, and relative rotations around the mediolateral axis measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, P ≥ 0.116.

INTERPRETATION

From a biomechanical perspective, anterior locked plating of complex patella fractures provides comparable fixation stability when using either a locking or a cortical polar screw.

Case Report: Bicondylar conjoined Hoffa fracture with incarcerated patella

Case

Hoffa fractures, uncommon injuries of the femoral condyle, sometimes involve both condyles, forming bicondylar fractures, typically from high-velocity trauma. We describe a 17-year-old male with an open conjoined bicondylar Hoffa fracture and a patellar fracture with incarceration following a road traffic accident. Emergency treatments included debridement, irrigation, and cannulated screw fixation. Postoperative care involved controlled range-of-motion exercises and specialized rehabilitation.

Conclusion

Despite its rare and severe nature, this conjoined bicondylar Hoffa fracture with patellar incarceration was successfully managed, showing excellent recovery. CT scans are vital for accurate injury definition and surgical planning. Anatomical reduction and rigid fixation enable early mobilization and excellent long-term outcomes.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Biomechanical Evaluation of Suture Augmentation of Dorsal Locking Plate Fixation in Transverse Patella Fractures

INTRODUCTION

Adjunctive suture augmentation of patellar plate fixation has yet to be investigated. Our biomechanical study sought to evaluate whether suture augmentation improves dorsal patellar locking plate fixation. Our hypothesis was that suture augmentation would improve fixation of this construct.

METHODS

A transverse patella fracture in six matched cadaveric pairs was stabilized using a patellar locking plate with or without suture augmentation. Specimens were tested at 60° knee flexion with load placed through quadriceps. Cyclic loading followed by load to failure was done. Stiffness, deformation at peak, and nonrecoverable deformation were calculated.

RESULTS

During cyclic loading, suture augmentation demonstrated a higher average stiffness throughout all loads. At the final cycle, deformation was markedly higher without suture augmentation. Average load to failure was higher with suture augmentation. Maximum load to failure occurred at 2500 N in both groups.

CONCLUSION

Suture augmentation in a transverse patellar fracture model improved dorsal plate fixation, leading to less fracture displacement at the final load. Although suture augmentation demonstrated higher stiffness and lower deformation, these trends were not statistically significant. In both groups, plate fixation sustained very high loads, which reflects the fixation strength of the dorsal locking plate and screw construct in this fracture model.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Analysis of postoperative complications 5 years after osteosynthesis of patella fractures-a retrospective, multicenter cohort study

PURPOSE

The study aims to investigate the influence of patient- and fracture-specific factors on the occurrence of complications after osteosynthesis of patella fractures and to compare knee joint function, activity, and subjective pain levels after a regular postoperative course and after complications in the medium term.

METHODS

This retrospective, multicenter cohort study examined patients who received surgery for patella fracture at level 1 trauma centers between 2013 and 2018. Patient demographics and fracture-specific variables were evaluated. Final follow-up assessments included patient-reported pain scores (NRS), subjective activity and knee function scores (Tegner Activity Scale, Lysholm score, IKDC score), complications, and revisions.

RESULTS

A total of 243 patients with a mean follow-up of 63.4 ± 21.3 months were included. Among them, 66.9% of patients underwent tension band wiring (TBW), 19.0% received locking plate osteosynthesis (LPO), and 14.1% underwent screw osteosynthesis (SO). A total of 38 patients (15.6%) experienced complications (TBW: 16.7%; LPO: 15.2%; SO: 11.8%). Implant-related complications of atraumatic fragment dislocation and material insufficiency/dislocation, accounted for 50% of all complications, were significantly more common after TBW than LPO (p = 0.015). No patient-specific factor was identified as a general cause for increased complications. Overall, particularly following complications such as limited range of motion or traumatic refracture, functional knee scores were significantly lower and pain levels were significantly higher at the final follow-up when a complication occurred. Implant-related complications, however, achieved functional scores comparable to a regular postoperative course without complications after revision surgery.

CONCLUSION

The present study demonstrated that implant-related complications occurred significantly more often after TBW compared to LPO. The complication rates were similar in all groups.

An innovative anti-rotation tension band wiring for treating transverse patellar fractures: finite element analysis and mechanical testing

BACKGROUND

The displacement and rotation of the Kirschner wire (K-wire) in the traditional tension band wiring (TBW) led to a high rate of postoperative complications. The anti-rotation tension band wiring (ARTBW) could address these issues and achieve satisfactory clinical outcomes. This study aimed to investigate the biomechanical performance of the ARTBW in treating transverse patellar fracture compared to traditional TBW using finite element analysis (FEA) and mechanical testing.

METHODS

We conducted a FEA to evaluate the biomechanical performance of traditional TBW and ARTBW at knee flexion angles of 20°, 45°, and 90°. Furthermore, we compared the mechanical properties under a 45° knee flexion through static tensile tests and dynamic fatigue testing. The K-wire pull-out test was also conducted to evaluate the bonding strength between K-wires and cancellous bone of two surgical approaches.

RESULTS

The outcome of FEA demonstrated the compression force on the articular surface of ARTBW was 28.11%, 27.32%, and 52.86% higher than traditional TBW at knee flexion angles of 20°, 45°, and 90°, respectively. In mechanical testing, the mechanical properties of ARTBW were similar to the traditional TBW. In the K-wire pull-out test, the pull-out strength of ARTBW was significantly greater than the traditional TBW (111.58 ± 2.38 N vs. 64.71 ± 4.22 N, P < 0.001).

CONCLUSIONS

The ARTBW retained the advantages of traditional TBW, and achieved greater compression force of articular surface, and greater pull-out strength of K-wires. Moreover, ARTBW effectively avoided the rotation of the K-wires. Therefore, ARTBW demonstrates potential as a promising technique for treating patellar fractures.

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

Purpose

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

Method

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

Results

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

Conclusion

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

Level of Evidence

Not Applicable.

Reconstruction of patella fractures with the tension band technique: A review on clinical results and tips and tricks

INTRODUCTION

The goals of surgical treatment of patellar fractures are a biomechanically stable joint and congruent restoration of the retro patellar joint surface. Surgical treatment strategies for patellar fractures have evolved from tension band in combination with wire cerclages to new devices.

METHODS

The modified anterior tension band (MATB) technique for fixation of patellar fractures consists of two longitudinal 1.8 mm Kirschner wires (K-wires) and an 18-gauge stainless steel wire looped in a figure-of-8 pattern over the anterior aspect of the patella. The K-wires should be inserted 5 mm from the anterior cortical surface of the patella, parallel in the coronal and sagittal planes. For mechanical reasons, the wire should be the closest to the anterior aspect of the bone. This construct converts the anterior tensile forces generated by the extensor mechanism and knee flexion into compressive forces on the anterior aspect of the fracture site. The MATB is the most widely accepted method of internal fixation for transverse and comminuted patellar fractures. Only a careful implementation of the MATB in all its phases will provide the best mechanical construct and the least aggressive construct for the soft tissues, allowing early re-education without complications.

RESULTS

Good to excellent clinical results (64-100 %) have been reported with MATB for fixation of patellar fractures. Good to excellent range of knee motion and satisfactory results have been reported despite a high percentage (up to 60 %) of secondary procedures, mainly for removal of symptomatic hardware.

CONCLUSION

This article provides an overview of the use and results of the MATB technique for patellar fractures and the means to improve results with this technique.

Patellar Fracture Surgery Performed Autonomously by Residents, Yields Similar Short-Term Outcomes to Surgery Performed by Fellowship-Trained Surgeons

BACKGROUND

Open reduction and internal fixation are the gold-standard treatment for displaced patellar fractures. The current literature remains inconclusive on the relationship between resident participation in the operating room and optimal patient outcomes. We hypothesize that surgeries performed solely by residents, without attending supervision, can provide similar outcomes to those performed by fellowship-trained orthopedic surgeons, providing new insights into the relationship between resident autonomy and surgical outcomes in the field of orthopedic trauma.

METHODS

A tertiary trauma center cohort was retrospectively reviewed for all surgically treated patellar fractures between 2015 and 2020. The cohort was divided into 2 groups: patients operated by residents and patients operated by orthopedic trauma specialists. Demographics, surgical parameters, and radiographs were compared between the groups to evaluate complications and reoperation rates, radiographic outcomes (such as hardware failure, or loss of reduction), and clinical outcomes (including residual pain, painful hardware, decreased range of motion, and infections).

RESULTS

A total of 129 patellar fractures were included in the study. Demographics and ASA were similar between the groups. There were no significant differences in complications (p = 0.900) or reoperation rates (p = 0.817), with an average follow-up time of 8 months (SD ± 5.3). Residents had significantly longer surgery duration (p =0.002). However, the overall length of stay was shorter in the resident group (p < 0.001).

CONCLUSION

The study shows patellar fracture surgery performed by adequately trained residents can provide similar outcomes to those performed by fellowship-trained orthopaedic trauma surgeons. These findings highlight the significance of surgical autonomy in residency and its role in contemporary surgical education.

Lateral rim variable angle locked plating versus tension band wiring of simple and complex patella fractures: a biomechanical study

INTRODUCTION

Treatment of both simple and complex patella fractures is a challenging clinical problem. Although tension band wiring has been the standard of care, it can be associated with high complication rates. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures.

MATERIALS AND METHODS

Sixteen pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34-C1 or five-part complex AO/OTA 34-C3 patella fractures by means of osteotomies, with each fracture model created in eight pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior (central distal) fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring or a lateral rim variable angle locking plate. Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full extension. Interfragmentary movements were captured via motion tracking.

RESULTS

For both fracture types, the articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p ≤ 0.01.

CONCLUSIONS

From a biomechanical perspective, lateral rim variable angle locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

A novel technique for treating simple transverse patellar fractures using cannulated screws: a cadaveric and clinical study

BACKGROUND

Tension band wiring (TBW) has conventionally been used for the open reduction and internal fixation of the patella. However, it suffers from distinct disadvantages such as large incision, implant irritation, and need for subsequent implant removal. Here, we propose a novel technique using closed reduction and percutaneous fixation with three cannulated screws (TCS), which may be an alternative to this established conventional technique. Although some researchers have proposed alternative methods including closed reduction and cannulated screw fixation, with or without additional wires through the screws, and arthroscopic-assisted reduction and fixation, there are few studies that focus on the biomechanical stability of percutaneous fixation using only cannulated screws. Thus, the purpose of this study was to evaluate TCS versus TBW for simple transverse patellar fractures in cadaveric and patients' level, aiming to determine whether TCS show superiority over TBW in terms of biomechanical stability in a cadaveric study with benign clinical feasibility and outcomes in patients.

METHODS

We conducted a cadaveric study with 15 knee specimens that had simple transverse patellar fractures. We used two fixation techniques: TBW (group A, n = 6) and TCS (group B, n = 9). We applied sinusoidal forces (25 N-125 N) at 1/5 Hz and 90° knee flexion to simulate knee movement. We compared the displacements at the fracture site between the two groups. We also used the same technique in a total of 23 patients and followed up them for at least 1 year.

RESULTS

TCS demonstrated favourable biomechanical stability in the cadaveric study. The technique also performed excellently in terms of postoperative pain, knee function recovery, and complication rates during the follow-up period.

CONCLUSIONS

The technique provides a surgical treatment option with small incisions, minimal soft tissue irritation, and possibly lower removal rate of bothersome material.

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.

A novel technique of a new cannulated screw for treatment of inferior pole patellar fractures: a finite element study

OBJECTIVE

We invented a new cannulated screw with holes on the tail, which called Ding's screw. The goal of this study was to evaluate the biomechanical outcomes of this new screw with tension band wiring for the treatment of inferior pole patellar fractures in a finite element model.

METHODS

We conducted a finite element biomechanical study using two fixation methods: Ding's screw and tension band wiring (DSTBW) and cannulated screws and tension band wiring (CSTBW). Two methods were simulated to fix the inferior pole patellar fracture in a finite element model. The relative displacement and stress distribution were analyzed and compared.

RESULT

There were less displacement and stress distribution of DSTBW in different knee movement (30°, 60°, 90°, 120°) when compared to CSTBW. The highest value of displacement of the fracture and von Mises stress of the internal fixation happened in 120° knee movement in both groups. The highest displacement of the DSTBW was less than that of the CSTBW (1.92 mm to 2.12 mm). The highest value of the stress on the screws was 110.60 MPa in DSTBW group, and 132.90 MPa in CSTBW group. The highest value of the stress on the titanium cable was 38.51 MPa in DSTBW group, and 41.91 MPa in CSTBW group.

CONCLUSION

DSTBW fixation provides more stability than CSTBW fixation model in a finite element study.

Comparison of a minimally invasive osteosynthesis technique with conventional open surgery for transverse patellar fractures

PURPOSE

The study aims to compare the efficacy and safety of a new minimally invasive osteosynthesis technique with those of conventional open surgery for transverse patellar fractures.

METHODS

It was a retrospective study. Adult patients with closed transverse patellar fracture were included, and with open comminuted patellar fracture were excluded. These patients were divided into minimally invasive osteosynthesis technique (MIOT) group and open reduction and internal fixation (ORIF) group. Surgical time, frequency of intraoperative fluoroscopy, visual analogue scale score, flexion, extension, Lysholm knee score, infection, malreduction, implant migration and implant irritation in two groups were recorded and compared. Statistical analysis was performed by the SPSS software package (version 19). A p < 0.05 indicated statistical significance.

RESULTS

A total of 55 patients with transverse patellar fractures enrolled in this study, the minimally invasive technique was performed in 27 cases, and open reduction was performed in 28 cases. The surgical time in the ORIF group was shorter than that in the MIOT group (p = 0.033). The visual analogue scale scores in the MIOT group were significantly lower than those in the ORIF group only in the first month after surgery (p = 0.015). Flexion was restored faster in the MIOT group than that in the ORIF group at one month (p = 0.001) and three months (p = 0.015). Extension was recovered faster in the MIOT group than that in the ORIF group at one month (p = 0.031) and three months (p = 0.023). The recorded Lysholm knee scores in the MIOT group were always greater than those in the ORIF group. Complications, such as infection, malreduction, implant migration, and implant irritation, occurred more frequently in the ORIF group.

CONCLUSION

Compared with the ORIF group, the MIOT group reduced postoperative pain and had less complications and better exercise rehabilitation. Although it requires a long operation time, MIOT may be a wise choice for transverse patellar fractures.

A Randomized Comparative Study of Functional and Radiological Outcome of Tension Band Wiring for Patella Fractures Using SS Wire Versus Fiberwire

Background

Patellar fractures account for 1% of all skeletal injuries. Tension band wiring using SS wire has been the most commonly practiced procedure. Although this has shown good results, many patients experience hardware related problems like pain, irritation and prominence which necessitate it's removal. Recent studies have highlighted braided sutures as a possible alternative to SS wire. The purpose of this study is to evaluate the functional and radiological outcomes and complications of TBW using SS wire versus FiberWire (a reinforced braided polyblend suture) for the treatment of displaced transverse patellar fractures.

Methods

A randomized comparative study was carried out at a tertiary care center from November 2019 to May 2021. 32 patients were randomized into two equal groups, one treated with TBW using FiberWire and the other with SS wire. Patients were followed up for a period of 20 weeks and evaluated for functional outcome using the Bostman scoring scale, radiological union, complications and hardware removal rates.

Results

The mean duration for radiological union was 12.85 weeks using FiberWire and 12.75 weeks using SS wire. The mean knee range of motion was 118.57° in the FiberWire group and 117.18° in the SS wire group. Functional scores in the FiberWire and SS wire groups were 24 (good) and 26 (good) respectively measured using the Bostman scoring scale at end of 20 weeks. Complications like hardware prominence, soft tissue irritation and hardware removal rates were significantly higher in the SS wire group with a p value of 0.023.

Conclusion

SS wire is biomechanically stronger than FiberWire when used for TBW. Both implants produce comparable results with respect to union rate, ROM and functional outcome, however, FiberWire causes fewer hardware complications like prominence and pain and hence alleviates the need for a second surgical procedure for implant removal. Thus, surgical treatment of transverse and inferior pole of patella fractures with TBW using FiberWire is a better alternative to SS wire considering early rehabilitation and lesser complication rates.

Anterior variable-angle locked plating versus tension band wiring of simple and complex patella fractures - a biomechanical investigation

BACKGROUND

The aim of this study was to investigate the biomechanical performance of novel anterior variable-angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures.

METHODS

Sixteen pairs of human cadaveric knees were used to simulate two-part simple transverse AO/OTA 34-C1 and five-part complex AO/OTA 34-C3 patella fractures. The complex fracture pattern was characterized with a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral and an inferior fragment mimicking comminution around the distal patella pole. Eight pairs with simple fractures were split for fixation via either tension band wiring (TBW) through two parallel cannulated screws or anterior variable-angle locked plating, whereas other eight pairs with complex fractures were split for either TBW through two parallel cannulated screws plus circumferential cerclage wiring, or anterior variable-angle locked plating using a cortical caudo-cranial polar screw. Each specimen was tested over 5000 cycles with a range of motion from 90° flexion to full extension by pulling on the quadriceps tendon. Interfragmentary movements were captured by motion tracking.

RESULTS

For both fracture types, the longitudinal and shear articular displacements, measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following anterior variable-angle locked plating versus TBW, p ≤ 0.01.

CONCLUSIONS

From a biomechanical perspective, anterior locked plating of both simple and complex patella fractures resulted in less interfragmentary displacement under extended cyclic loading.

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.

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.

A Novel Technique for the Treatment of Inferior Pole Fractures of the Patella: A Preliminary Report

Objective

Most inferior pole fractures of the patella are comminuted. Therefore, an ideal treatment method has not been determined. We have presented a modified tension band fixation technique—the Krachow suturing, Nice knot combined with tension band fixation—and reported the results of the procedure.

Methods

A total of 16 inferior patellar pole fractures were treated at our institution between January 2019 and October 2020, 15 of which underwent treatment with the modified tension band fixation technique consisting of Krachow suturing with Nice knots combined with tension band fixation. The primary measures: knee motion, Bostman score, anterior knee pain, fixation failure.

Results

Bone union occurred at a mean of 9 weeks postoperatively (range: 8–13). There were no cases of postoperative anterior knee pain, refracture of the inferior patellar pole or wire breakage. The patients regained full ROM of the knee joint without functional deficits during follow‐up; the mean ROM was 128.46° ± 7.07° (range: 113.4°–137.8°). At the last follow‐up, all patients had a mean Bostman score of 28.40 ± 1.29 (range: 26–30), with an excellent score in 11 patients and a good score in four patients.

Conclusion

The modified tension band fixation technique for the treatment of inferior patellar pole fractures is a simple and easy‐to‐perform surgical technique that provides stable fixation and good functional results.

The clinical outcomes and complications of combined fixation with cannulated screws and the modified Pyrford technique for the treatment of transverse patellar fractures: a case series study

Background

Transverse patellar fractures can be fixed using various techniques. The purpose of the current study was to assess the clinical outcomes and complication rate of a combined fixation technique using cannulated screws and the modified Pyrford technique with nonabsorbable polyester sutures.

Methods and patients

Between January 2015 and February 2021, 26 transverse patellar fractures were fixed with this combined technique. Preoperative data were collected from patients with transverse patellar fractures who were followed up for at least 12 months. At each follow-up visit, plain radiographs were taken. At the 12-month postoperative follow-up, range of motion of the affected knee joint and clinical outcomes, as evaluated by the Bostman scoring system, were recorded.

Results

The average Bostman score at the 12-month postoperative follow-up was 28.3 ± 1.5. Furthermore, the average extension and flexion of the knee joint were 1.2 ± 2.1 and 125.6 ± 6.7 degrees, respectively. One patient experienced delayed bone union and one experienced superficial wound infection. There were no other postoperative complications. One patient required removal of the device for social-psychological reasons.

Conclusions

The combined fixation technique with cannulated screws and the modified Pyrford technique with suture materials produced excellent clinical outcomes and a low rate of complications in the treatment of transverse patellar fractures.

Biomechanical comparison of a novel tensioned cable construct versus tension band wiring for transverse patella fracture fixation

PURPOSE

Tension band wiring (TBW) is the most widely accepted method for patella fracture fixation. The purpose of our study was to compare the biomechanical efficacy of a novel cable construct to TBW for the fixation of transverse patella fractures. The tensioned cable construct was hypothesized to have less fracture gapping after cyclic flexion-extension loading and greater ultimate load to failure as compared to TBW.

METHODS

Transverse patellar osteotomies (AO/OTA 34C1.1) were performed on nine pairs of fresh-frozen human cadaveric whole legs (mean age 82.2 years, range 71-101). Treatment with TBW or tensioned cable construct was randomized within each specimen pair. Fracture site displacement was measured after 5000 flexion-extension cycles from 0° to 90° at 0.5 Hz. In load to failure testing, the knee was fixed at 45° of flexion and the quadriceps tendon was pulled proximally at 0.5 mm/sec until patella fixation failure. Comparisons were made using paired t-tests with alpha values of 0.05.

RESULTS

Eight paired specimens completed the cyclic loading. The tensioned cable construct had significantly less fracture gapping than TBW (2.9 vs 10.9 mm; p = 0.020). Seven paired limbs underwent load to failure testing, which revealed no significant difference between the tensioned cable construct and TBW (1551.6 N vs 1664.0 N; p = 0.26).

CONCLUSION

In this study of transverse patella fracture fixation, a tensioned cable construct demonstrated significantly less fracture gapping compared to TBW in response to cyclic loading with no significant difference in load at failure.

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

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

Lag screw osteosynthesis of simple olecranon fractures: A biomechanical comparative study

Olecranon fractures are most frequently stabilized by tension band wiring (TBW), which unfortunately leads to relevant implant removal rates due to K-wire migration and soft tissue irritation. As lag screw osteosynthesis (LSO) might be a gentle and effective alternative in simple fracture patterns, the goal of the present study was to biomechanically compare LSO with TBW in simple olecranon fractures at a cadaver model. A simple olecranon fracture (Mayo type IIA) was created in eight pairs of human cadaver elbows, which were pairwise fixed by either TBW or two transcortical 4.0 mm lag screws. Biomechanical testing was conducted as a pulling force, applied to the triceps tendon in a 90° position. First, cyclic loading between 10 and 300 N was performed for 50,000 cycles. Afterward, maximum load was raised by 0.02 N/cycle until construct failure, what was defined as displacement >2 mm. Besides fracture displacement, failure cycle and failure load, the modes of failure were analyzed. Within the first five cycles, there was no significant difference in displacement (median TBW: 0.2 mm; LSO: 0.5 mm; p = 0.091). Both after 2000 (median TBW: 0.2 mm; LSO: 0.6 mm; p = 0.042) and after 20,000 cycles (median TBW: 0.4 mm; LSO: 0.9 mm; p = 0.027), the difference was significant. Failure cycle (median TBW: 72,639 cycles; LSO: 43,429 cycles; p = 0.017) and failure load (median TBW: 702 N; LSO: 303 N; p = 0.025) differed significantly as well. TBW mostly (6/8) failed at the lock of the cerclage wire, whereas most LSO constructs (5/8) failed as a pullout of the proximal fragment. In conclusion, to our biomechanical findings at human cadaver specimens, simple olecranon fractures treated by LSO show higher dislocation rates and lower failure loads compared to conventional TBW and mostly fail by pullout of the proximal fragment.

Vertical Patella Fracture Fixed by Plate and Screws With Bone Graft: A Case Report

Fractures of the patella constitute approximately 1% of all skeletal injuries. The vertical pattern represents 12-17% and the open patella fracture represents 6-30%. We here represent a rare case constituting the presence of these two uncommon (vertical type patella fracture with depression of articular surface). A 22-year-old male had a close patella fracture after a road traffic accident. The fracture was classified as a vertical and comminuted pattern. A back slab above the knee was applied and then the patient was prepared for surgery. Open reduction and internal fixation of the patella by miniplate and bone graft restore the articular surface, which reduces the risk of post-traumatic osteoarthritis. At five months postoperatively, the patient had a satisfactory joint motion with full extension and 120° of joint flexion and returned to his daily life activities without restriction. Additionally, the patient was in good health and able to bear full weight. In conclusion, the treatment choice requires a thorough knowledge of the case to ensure good stability and avoid fracture displacement.

Outcomes for a custom-made anchor-like plate combined with cerclage in the treatment of inferior pole patellar fracture

Objective

An inferior pole fracture of the patella requires surgical treatment to restore the knee extension mechanism of the knee joint. Different from other types of patellar fractures, inferior pole fractures are usually comminuted, and other traditional fixation methods, such as tension band wiring, may not meet the fixation needs. We propose fixing inferior pole fractures of the patella with a custom-made anchor-like plate combined with cerclage and report the surgical outcomes.

Material and methods

This is a retrospective clinical study. From June 2018 to August 2020, 21 patients with inferior patella fracture treated at Hong Hui Hospital Affiliated to Xi’an Jiaotong University received a custom-made anchor-like plate combined with cerclage. Complications of the surgical fixation methods and final knee function were used as the main outcome measures.

Results

All fractures achieved good union, and the union time ranged from 8 to 12 weeks. No patients had serious complications, such as internal fixation failure or infection. The average duration of surgery of patients was 75.05 7.26 min, and the intraoperative blood loss was 60.099.49 ml. At the last follow-up, the range of motion of the knee was 120°-140°, with an average of 131.436.92°, the Bostman score was 27–30, and the Lysholm score ranged from 82 to 95. All patients showed good knee function one year after the operation.

Conclusion

We used a modified T-shaped plate combined with cerclage technology to fix inferior fractures pole of the patella, providing reliable fixation, allowing early functional exercise of the knee joint, and providing patients with good knee joint function after surgery.

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.

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

INTRODUCTION

The incidence of patella fracture is statistically low (0.5-1.5%) compared to other fractures of the extremities [Patella fractures 76(10):987-997, 2005]. In the latter research, patella fractures if treated surgically present an overall inferior functional outcome. Little is known about the influence of the postoperative patella height on the clinical outcome. Therefore, the aim of our study was to analyse the influence of the patella height on the patients' functional outcome after surgery.

METHODS

In this retrospective study the in-house trauma register of our level I University trauma center was screened for patients suffering patella fractures treated surgically. Patella height of the same patients was evaluated on lateral X-rays using the Insall-Salvati Ratio (ISR). The patients' X-rays were analyzed at two time points for the ISR, whereas group A presents ISR data right after surgery and group B data at the latest follow up (minimum 6 weeks). The change of mean ISR at both time points was tested for significance. The functional outcome was measured by the "Munich Knee Questionaire" (MKQ). These MKQ results of different patella heights and fracture types were compared.

RESULTS

The screening of our in-house trauma register revealed 375 patients between the years 2003 and 2016. Out of these 54 patients (34f, 20 m) were enrolled. In detail the follow-up time for ISR between group A and B accounted for a mean of 503.8 ± 655.7 days. The MKQ was assessed at a mean of 1367.0 ± 1042.8 days after surgery. According to the AO-classification 10% AO.34 type B and 90% AO.34 type C fractures were found. Group A showed in 9.1% a patella baja and in 27.3% a patella alta compared to group B presenting 20.0% patella baja and 14.5% patella alta. There was no significant difference in functional outcome referring to the MKQ in patella alta (MKQ 69.0% ± 18.2) or baja (MKQ 67.1% ± 17.9) (p = 0.9). No significant functional difference between AO34.type B (MKQ 74.5% ± 11.0) and AO34.type C fractures (MKQ 64.0% ± 15.0) resulted (p = 0.1).

CONCLUSION

Our results demonstrate that different postoperative patella heights apparently do not influence the functional outcome in the short follow-up.

Radiographic Outcomes Following the Suture Fixation of Mid-pole Patellar Fractures

Background

Mid-pole patellar fractures are typically fixed with metal implants in the conventional “11-8” tension band construct. However, this technique is fraught with numerous implant-related complications. The aim of this study is to evaluate the union rate following “all-suture” fixation of mid-pole patellar fractures.

Methods

We retrospectively evaluated a consecutive case series of patients with displaced mid-pole patella fractures treated with “all-suture” fixation in our institution. Fifteen cases were available for this study. The average age was 61.5 years. Clinical and radiological outcomes were evaluated. Union time, complications, and revision rate were recorded. The minimum follow-up was one year.

Results

There were eight males and seven females, with a mean age of 61.5 ± 13.3 years. Fourteen out of 15 cases (93.3%) achieved radiographic union at 12 weeks postoperatively. The average time to radiographic union was 8.0 ± 2.7 weeks. Five cases (33.3%) had an increase in the fracture gap (>2 mm) at around four to six weeks postoperatively. Four of these cases had an eventual union, whereas one patient had fibrous non-union. There was one case of superficial surgical site infection and one case of infected hematoma. None of the patients required revision surgery.

Conclusion

“All-suture” fixation of mid-pole transverse patellar fractures is a safe and viable alternative to the conventional “11-8” tension band constructs with metal implants, with good union time, rates, and added benefits of not requiring additional surgery for implant removal.

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.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Comparative study on the effectiveness of improved and traditional Kirschner wire tension band fixation in treatment of type C patellar fractures]

Objective

To compare the effectiveness of improved and traditional Kirschner wire tension band fixation in treatment of type C patellar fractures.

Methods

Between January 2017 and January 2019, 26 patients with type C patellar fractures were treated with improved Kirschner wire tension band fixation (group A), and 24 patients were treated with traditional Kirschner wire tension band fixation (group B). There was no significant difference in gender, age, injury cause, disease duration, and side and type of fracture between 2 groups ( P>0.05). The operation time, intraoperative blood loss, the visual analogue scale (VAS) scores at 1 and 3 days after operation, the fracture healing time, and the occurrence of complications (skin irritation of Kirschner wires, failure of internal fixation, fracture reduction loss) were recorded, and the knee function was evaluated by Lysholm scoring standard in 2 groups.

Results

The operation time in group A was significantly less than that in group B ( t=-4.742, P=0.000). There was no significant difference in the intraoperative blood loss and VAS scores at 1 and 3 days after operation between 2 groups ( P>0.05). All incisions healed by first intention. All patients were followed up 8-15 months, with an average of 11 months. The fracture healing time was (3.3±0.6) months in group A and (3.2±0.6) months in group B, showing no significant difference ( t=0.589, P=0.559). At last follow-up, the knee joint function was evaluated according to Lysholm scoring standard. And there were 15 cases of excellent, 8 cases of good, and 3 cases of fair, with an excellent and good rate of 88.5% in group A; there were 8 cases of excellent, 7 cases of good, 7 cases of fair, and 2 cases of poor, with an excellent and good rate was 62.5%. The difference between 2 groups was significant ( Z=2.828, P=0.005). The internal fixators were removed after the fracture healed in 2 groups. At last follow-up, no skin irritation of Kirschner wires occurred in group A, but 3 cases in group B. X-ray films reexamination showed that 5 cases of internal fixation failure and no fracture reduction loss were found in group A, while 9 cases of internal fixation failure and 1 case of fracture reduction loss in group B. The incidence of complications in group A was 19.2% (5/26), which was significantly lower than that in group B (54.2%, 13/24) ( χ ²=6.611, P=0.010).

Conclusion

Compared with the traditional Kirschner wire tension band fixation, the improved Kirschner wire tension band fixation in treatment of type C patellar fracture can shorten the operation time, reduce the incidence of complications, and benefit the functional recovery of knee joint.

Long-term outcomes after partial patellectomy in comminuted fractures - a clinical study

PURPOSE

The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of partial patellectomy (PP) in patients with patella comminuted distal pole fractures.

METHODS

Seventeen patients who were diagnosed with patella comminuted distal pole fractures and underwent PP procedures were retrospectively included between January 1995 and January 2005. We collected patient demographics and data on the mechanism of injury, time to surgery, fracture type, follow-up time, and post-operative complications (infection, patellofemoral arthritis, and stiffness). At the final follow-up, functional outcome was evaluated by the range of motion (ROM) and the Bostman Scoring System. Quadriceps strength was evaluated by using an isokinetic dynamometer to measure peak torque, and patellar height was evaluated by the Insall-Salvati (IS) ratio in lateral knee radiographs. The average follow-up period was 14.6 years (range, 11-19 years).

RESULTS

We analyzed 17 patients (AO/OTA 34-A1), with an average age of 59.8 years (range, 43-76 years). According to the Bostman grading scales, final functional outcomes were excellent in 11 (64.7%) and good in six (35.3%) patients. All patients had full knee extension, and the average ROM was 125.1° (range, 121.4-129.3°). The average peak torque of the injured knee was 103.2 ± 9.7 Nm, and that of the uninjured opposite side was 108.3 ± 7.6 Nm, with no significant difference (p > 0.05). Furthermore, no postoperative complications, such as infection, posttraumatic osteoarthritis, or stiffness, were observed. Compared to the uninjured knee, the IS ratio of the injured knee was 0.76 ± 0.13, indicating that the patellar height was decreased, which meant patella baja.

CONCLUSIONS

The PP procedure for patella comminuted distal pole fractures is a safe, simple, and reliable technique that can provide good long-term clinical outcomes even with decreased patellar height and could be a satisfactory alternative treatment option when anatomical reduction is difficult.

Abstaining from symptomatic implants of modified tension band wiring by nonabsorbable suture fixation for transverse patella fractures

BACKGROUND

Modified tension band fixation has become commonly used for transverse patella fractures. The conventional stainless steel wire provides sufficient stability but may be associated with complications.

OBJECTIVE

The study aimed to evaluate the effectiveness of a new modified tension band fixation technique for transverse patella fractures using a nonabsorbable suture.

MATERIAL AND METHODS

We present the result of a prospective series using a nonabsorbable suture (FiberWire) for transverse patella fractures. The mean follow-up period totaled 12 months. A total of 16 patients were evaluated by radiographic and clinical review. The postoperative clinical evaluation employed Lysholm and Böstman scores.

RESULT

All clinical results on follow-up were good to excellent. Minimal intra-articular joint stepping and further fracture displacement were recorded. No patient needed re-operation, and functional outcomes of the knee were satisfactory. No significant differences were found between the injured and contralateral knee range of motion. No symptomatic implants and skin complications were noted, and all fractures were completed heal within 15 weeks.

CONCLUSION

FiberWire provided sufficient stability and reduced postoperative complications. The results proved appropriate, and the technique has merit, as it obviates the need for re-operation.

Internal fixation and unicompartmental knee arthroplasty for an elderly patient with patellar fracture and anteromedial osteoarthritis: A case report

BACKGROUND

Open reduction and internal fixation (ORIF) is the traditional surgical treatment for patellar fractures, and unicompartmental knee arthroplasty (UKA), especially Oxford UKA, has been increasingly used in patients with medial knee osteoarthritis (OA). However, the process of choosing treatment for patients with both patellar fractures and anteromedial knee OA remains unclear. We present the case of a patient with a patellar fracture and anteromedial OA.

CASE SUMMARY

We present the case of a 72-year-old woman with a history of bilateral medial compartment OA of the knees and a right Oxford UKA. She also experienced a recent left patellar fracture. ORIF and Oxford UKA were performed in a single stage. The patient showed excellent postoperative clinical results.

CONCLUSION

ORIF and Oxford UKA can be performed simultaneously for patients with patellar fracture and anteromedial OA on the same knee.

Patellar Fracture Fixation With Cannulated Compression Screws and FiberTape Cerclage

Transverse patella fractures with loss of knee extensor mechanism function are a common orthopaedic injury requiring operative fixation. Current accepted surgical options for noncomminuted transverse fractures include open reduction with tension band wiring. Although these procedures result in good clinical outcomes and fracture healing, symptomatic hardware from the historically used metal implants is very common. The purpose of this Technical Note is to describe a technique for treatment of transverse patellar fractures using cannulated compression screws with tensioned high-resistance suture tape functioning as the tension band. This technique provides effective, reproducible fracture fixation while minimizing symptomatic hardware, failure, and reoperation.

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.

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.