Distal Femur Locking Plates Fit Poorly Before and After Total Knee Arthroplasty

Risk of reverse golf club deformity with medial plating of distal femur fracture

INTRODUCTION

This study described a deformity induced by medial plating of supracondylar distal femur fractures using plates that are precontoured for other anatomic locations.

MATERIALS AND METHODS

OTA/AO 33A fractures were created in 12 sawbone femurs and fixed with either a proximal humerus locking plate (PH), an ipsilateral lateral tibial plateau plate (LTP), or an ipsilateral medial distal tibial plate (MDT). A motion capture system measured changes in length and rotation of the distal femur as the plate was applied. Each plate underwent four trials and the mean and standard deviation (SD) for each measurement was reported. An analysis of variance with post hoc Tukey test compared malreduction measures between plate types.

RESULTS

All plates consistently created a varus deformity. There was lateral lengthening with a compensatory medial shortening and an increase in the lateral distal femoral angle. The distal fracture fragment was laterally translated, and internally rotated. The PH plate had significantly greater lateral length (27.39 mm SD 4.78, p = 0.007), shorter medial length (13.57 mm SD 4.99, p = 0.028), greater lateral translation (28.82 mm SD 5.70, p = 0.010) and greater widening of the lateral distal femoral angle (28.54° SD 4.98, p < 0.001) than the LTP and MDT plates. The MDT plate had significantly greater angulation anteriorly (8.40° SD 1.07, p < 0.001) and laterally (7.63° SD 3.10, p = 0.002) than the PH and LTP plates. There was no significant difference between plates in internal rotation (PH: 3.07° SD 2.79; LTP: 2.05° SD 1.05; MDT 3.81° SD 3.56; p = 0.659).

CONCLUSION

When dual plating supracondylar distal femur fractures, poor plate positioning and a mismatch between plate contour and the slope of the medial distal femur can lead to varus angulation, internal rotation, and lateral translation or a "reverse golf club deformity". After comparing three types of precontoured plates, the authors recommend initial evaluation of the ipsilateral proximal tibial plate when placing a plate along the medial distal femur.

LEVEL OF EVIDENCE

IV.

Retrograde Intramedullary Nailing Versus Locked Plating for Extreme Distal Periprosthetic Femur Fractures: A Multicenter Retrospective Cohort Study

OBJECTIVES

To compare clinical and radiographic outcomes after retrograde intramedullary nailing (rIMN) versus locked plating (LP) of "extreme distal" periprosthetic femur fractures, defined as those that contact or extend distal to the anterior flange.

METHODS

DESIGN

Retrospective review.

SETTING

Eight academic level I trauma centers.

PATIENT SELECTION CRITERIA

Adult patients with periprosthetic distal femur fractures at or distal to the anterior flange (OTA/AO 33B-C[VB1]) treated with rIMN or LP.

OUTCOME MEASURES AND COMPARISONS

The primary outcome was reoperation to promote healing or to treat infection (reoperation for elective removal of symptomatic hardware was excluded from this analysis). Secondary outcomes included nonunion, delayed union, fixation failure, infection, overall reoperation rate, distal femoral alignment, and ambulatory status at final follow-up. Outcomes were compared between patients treated with rIMN or LP.

RESULTS

Seventy-one patients treated with rIMN and 224 patients treated with LP were included. The rIMN group had fewer points of fixation in the distal segment (rIMN: 3.5 ± 1.1 vs. LP: 6.0 ± 1.1, P < 0.001) and more patients who were allowed to weight-bear as tolerated immediately postoperatively (rIMN: 45%; LP: 9%, P < 0.01). Reoperation to promote union and/or treat infection was 8% in the rIMN group and 16% in the LP group ( P = 0.122). There were no significant differences in nonunion ( P > 0.999), delayed union ( P = 0.079), fixation failure ( P > 0.999), infection ( P = 0.084), or overall reoperation rate ( P > 0.999). Significantly more patients in the rIMN group were ambulatory without assistive devices at final follow-up (rIMN: 35%, LP: 18%, P = 0.008).

CONCLUSIONS

rIMN of extreme distal periprosthetic femur fractures has similar complication rates compared with LP, with a possible advantage of earlier return to weight-bearing. Surgeons can consider this treatment strategy in all fractures with stable implants and amenable prosthesis geometry, even extreme distal fractures.

LEVEL OF EVIDENCE

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

Apex posterior angulation of the humerus: A characterization of normal sagittal plane anatomy with implications for surgical fixation

INTRODUCTION

An understanding of the sagittal plane morphology of the humerus is relevant during surgical fixation of humeral fractures but is not well described in the literature. The purpose of this study was to better characterize the native sagittal plane morphology of the humerus.

MATERIALS AND METHODS

170 patients with uninjured full length lateral humerus radiographs were retrospectively evaluated. The angle between the proximal humeral diaphyseal axis and the distal humeral diaphyseal axis was identified and measured. The proximal axis was defined by two points equidistant from the anterior and posterior cortex 10 mm and 100 mm distal to the metaphyseal flare, and the distal axis by two points at 10 mm and 50 mm proximal to the capitellum/trochlea. The relative location of the center of rotation of angulation (CORA) was calculated as a percentage of humeral length.

RESULTS

114 radiographs were included in the analysis (66 right humeri, 48 left humeri). The average apex posterior angulation was 6.5 +/- 2.9°. The CORA occurred at an average of 80% (SD+/-13%) of the length of the humerus (proximal to distal). Total humeral length and absolute distance to CORA were greater in males compared to females (364 ± 50 mm versus 326 ± 30 mm; p<0.001; 290 ± 68 mm versus 260 ± 48 mm; p=0.003), but there were no significant sex differences with respect to magnitude of the apex posterior angulation (p=0.077) or location of CORA as a percentage of total humeral length (p=0.916). There were no statistically significant associations between age and total humeral length (p=0.056), distance to CORA (p=0.130), location of CORA as percentage of total humeral length (p=0.753), or magnitude of angulation (p=0.075).

CONCLUSION

An apex posterior bow consistently exists in the distal one-quarter of the humerus that is consistent across ages and between sexes. This normal anatomic bow is important to recognize to avoid an extension malreduction and has implications for implant fit and contouring.

Axial and Rotational Malreduction (Golf Club Deformity) in Distal Femur Fractures

OBJECTIVES

To describe malreduction of supracondylar distal femur fractures stabilized with lateral femoral locking plates and determine whether a mismatch in axial lateral distal femur anatomy and lateral distal femoral plate design contributes to supracondylar distal femoral fracture malreduction.

MATERIALS AND METHODS

OTA/AO 33A were simulated in 7 cadaver femurs and fixed with a lateral distal locking femoral plate placed flush to the lateral femoral condyle (group 1). In group 2, the anterior flange of the plate was externally rotated 10 degrees in relation to the lateral condyle. A motion capture system measured translation and rotation of the articular segment as shaft screws were applied, reducing plate to femoral diaphysis. Articular segment movement was compared between groups using paired Student t test, P &lt; 0.05. A large database of 3D scans of 800 femurs was used to define the relationship of the lateral femoral condyle to the lateral cortical surface of the human femur.

RESULTS

Malreduction was observed with anatomic plate application results from medial translation (17 mm) and external rotation (12.2 degrees) (group 1). Modifying plate geometry to match lateral femur anatomy (group 2) improved medial translation by 46% and external rotation by 80%. An analysis of the shape of the 800 distal femurs showed that the average posterior anterior inclination is 16.5 degrees.

CONCLUSIONS

Anatomic application of distal femoral plates results in significant malreduction. Modifying the plate design to accommodate 10 degrees slope of lateral distal femur results in partial correction of deformity. Future studies should investigate other means of correcting the malalignment, especially considering the 16.5-degree posterior anterior inclination of the condyle.

Point-of-Care 3D Printing: A Feasibility Study of Using 3D Printing for Orthopaedic Trauma

AIM

The aim of this study was to assess the feasibility of 3D printing a customised implant at the point of care from a manufacturing and logistics perspective. We hypothesised that customised plate production would be possible within a clinically relevant time frame of 72 hours using currently available technology.

MATERIALS AND METHODS

This study uses 6 cadaveric lower limbs to simulate real-life surgical patients. Split-depressed lateral tibial plateau fractures were created in an identical fashion in the cadaveric lower limbs. CT scans of the fractures were obtained and digital reconstructions were used to design customised patient and fracture-specific 3D-printed plates. These were subsequently printed in medical grade stainless steel 316L and post-processed at a local additive manufacturing centre. Surgical fixation of the fractures was then carried out using these plates, following which post-operative X-rays were obtained. The time taken for each step in plate production from the initiation of pre-operative CT scan to the completion of the post-operative X-ray was recorded.

RESULTS

Six customised proximal tibia locking plates were produced with accompanying surgical drill guides. The mean total time taken for plate fabrication from completion of CT scan was approximately 24 hours and 7 minutes, with a maximum of 28 hours and 46 minutes.

CONCLUSION

Production of patient-specific 3D printed plates for fixation of proximal tibia fractures at the point of care is achievable within a clinically acceptable time frame provided adequate manufacturing facilities and skilled manpower are in place.

Surgical Tips and Tricks for Distal Femur Plating

Distal femur fractures are challenging fractures to treat, with nonunion rates as high as 22%. Precontoured locking plates have mitigated some earlier causes of failure, while introducing new challenges. The recognition of troublesome injury patterns and appropriate preoperative planning can avoid common pitfalls. Adjunctive techniques, including the use of a radiolucent triangle, an external fixator, unicortical plates, and crossing K-wires, can assist with fracture reduction and maintenance. It is important to understand the common pitfalls involved with distal femur plating and to consider a wide array of techniques to combat these challenges.

Outcomes of distal femoral arthroplasty after periprosthetic fractures: minimum 2-year follow-up

Purpose : distal femoral periprosthetic fracture (DFPPF) is a serious complication following total knee arthroplasty (TKA). Recently, treatment of DFPPF with distal femoral arthroplasty (DFA) has gained popularity because of its posited benefits for both patients and the medical system. Short-term follow-up trials investigating DFA have demonstrated acceptable results with regards to function, pain relief and lower postoperative complications than ORIF in elderly patients. The purpose of the current study was to evaluate a consecutive series of DFPPF treated with DFA, with a minimum 2- year follow-up. Methods : We performed a retrospective study asses- sing the outcomes of distal femoral arthroplasty (DFA) for patients diagnosed with DFPPF. Results : Twenty patients were identified. The mean age of patients was 76.3 (SD, 9.41), the average time from the fracture to revision surgery was 6.7 days (SD, 11.35), The average operative time was 93.5 minutes (SD,16.6). The average follow-up time was 50.15 months (SD, 20.87). During this time, two patients (10%) had complications. One patient experienced a knee dislocation and the second patient had recurrent periprosthetic infections. At final follow up, the mean knee society score was 86.25 (SD, 9.44), the mean Forgotten joint score was 62.16(SD, 23.45) and 93.7 percent of patients were ambulatory. Conclusion : DFA following DFPPF is associated with high success rates and provides patients with the opportunity for return of function in a safe and reliable manner.

Low profile fragment specific plate fixation of lateral tibial plateau fractures - A technical note

PURPOSE

Precontoured plates used to stabilize lateral tibial plateau (LTP) fractures are limited in their ability to raft particular areas of the reconstructed articular surface. These implants also do not fit every individual's bony anatomy and can lead to soft tissue irritation. The purpose of this study was to evaluate fragment specific plate fixation of LTP fractures using generic small and mini fragment constructs.

METHODS

This was a retrospective case series of LTP fractures treated with small fragment tubular and/or mini fragment plate constructs at a single Level I trauma center. Postoperative complications were recorded. Final radiographs were analyzed to determine union and interval subsidence of the articular surface and/or loss of reduction.

RESULTS

All 19 LTP fractures healed without loss of reduction or implant failure. There was minimal interval subsidence of the LTP in all patients. There were no complications or reoperations for symptomatic implant removal within the given follow-up period.

CONCLUSION

Fragment specific fixation of LTP fractures using small and mini fragment plates creates a lower profile construct that reliably maintains fracture reduction to union.

Complication Rates after Lateral Plate Fixation of Periprosthetic Distal Femur Fractures: A Multicenter Study

OBJECTIVE

Periprosthetic fractures of the distal femur can be challenging injuries to treat; nonunion rates of up to 22% have been reported. The purpose of this study was to determine the rate of complications and nonunion in a multicenter series, and to identify patient or surgical factors that were associated with nonunion.

DESIGN

Retrospective comparative study SETTING: Three Level 1 trauma centers PATIENTS: Fifty-five patients with a periprosthetic distal femur fracture proximal to a total knee arthroplasty. Minimum follow up for inclusion was six months or until union or failure.

INTERVENTION

Surgical fixation using a precontoured lateral locking plate MAIN OUTCOME MEASUREMENT: Fracture union was the primary outcome. Patient demographic and injury variables (age, comorbidities, fracture classification and characteristics) and surgical technique factors (mode of plate fixation, plate material, working length, screw density, and proximal screw type) were identified and compared between patients who developed a nonunion and those who did not. Regression analysis was performed to identify independent risk factors for nonunion.

RESULTS

The overall rate of nonunion was 18% and the total complication rate was 24%. After additional surgery, 49 of 55 patients went on to heal (89%). There were no statistical differences in patient demographic or injury variables between the union and nonunion groups, and none of the variables studied were independent risk factors for nonunion in the regression analysis.

CONCLUSIONS

In this series of 55 patients with periprosthetic distal femur fractures treated with precontoured lateral locking plates, 18% developed nonunion and the overall complication rate was 24%. No patient or surgical variables were identified as risk factors. Future research should seek to identify patients at high risk for complication and nonunion who could benefit from alternative fixation strategies or distal femoral replacement.

Contouring Plates in Fracture Surgery: Indications and Pitfalls

Effective fracture surgery requires contouring orthopaedic implants in multiple planes. The amount of force required for contouring is dependent on the amount and type of material contained within the plane to be altered. The type of contouring used depends on the desired plate function; for example, buttress mode often requires some degree of undercontouring, whereas compression plating may require prebending. Other reasons to contour a plate include matching patient anatomy either to maximize fixation options or to reduce implant prominence. Precontoured plates can be convenient and help to facilitate soft-tissue friendly techniques but have the potential to introduce malreduction if the plate position and fit are not carefully monitored.

Analysis of the fit of modern pre-contoured distal femur plates: Expect an imperfect contour

The purpose of this study was to determine if the contour of current distal femur plates can reliably be used as a reduction tool and to determine if the presence of a total knee arthroplasty (TKA) influences fit. Thirty-two patients were retrospectively reviewed. Radiographs of 19 patients with normal knees and 21 patients who had undergone TKA were evaluated. Using TraumaCad templating software, the contours of 4 different modern distal femur plates (Depuy Synthes, Stryker, Zimmer Biomet, and Smith & Nephew) were analyzed using a novel measurement technique to evaluate plate fit. To mimic non-locking screws in the shaft, the template was placed on the shaft and the plate to bone (PTB) and condyle to plate (CTP) distances were recorded. The PTB distance measured how closely the plate matched the contour of the metaphyseal flare, while the CTP value represented the distance from the plate to the distal articular surface. Larger PTB and CTP distances represent a higher mismatch between the patient's anatomy and the contour of the plate. There was significant variability in plate fit in all patients. None of the plates fit the patient's anatomy well, with PTB values averaging from 5.5 mm to 9.2 mm. There was no significant difference between normal radiographs and TKA radiographs, suggesting that the presence of a TKA may not contribute to plate fit. The results of this study show that current plate designs may not match the patient's native anatomy prior to fracture. Therefore, caution should be utilized when using non-locking screws in the shaft and using the pre-contoured nature of the plate as a template for reduction. The authors advocate for careful preoperative planning and using contralateral radiographs for templating purposes to prevent malreduction and to assist in device selection for the best device fit per patient.