Minimally invasive open reduction combined with proximal femoral hollow locking plate in the treatment of Pauwels type III femoral neck fracture

Biomechanical evaluation of percutaneous compression plate and femoral neck system in Pauwels type III femoral neck fractures

BACKGROUND

The optimal treatment for Pauwels type III femoral neck fractures remains contentious. We aim to compare the biomechanical properties of three inverted cannulated compression screw (ICCS), femoral neck system (FNS), and percutaneous compression plate (PCCP) to determine which offers superior stability for unstable femoral neck fractures.

MATERIALS AND METHODS

Finite element analysis and artificial bone models were used to establish Pauwels III femoral neck fracture models. They were divided into ICCS, FNS, and PCCP groups based on respective internal fixation assemblies. The models were subjected to vertical axial loads (2100 N) and torsional forces (10 N × mm) along the femoral neck axis in the finite element analysis. The primary outcomes such as the Z axis fragmentary displacements, as well as displacements and the von Mises stress (VMS) distributions of internal fixations, were analyzed. Additionally, the artificial bones were subjected to progressively increasing vertical axial pressures and torsional moments at angles of 2°, 4°, and 6°, respectively. The vertical displacements of femoral heads and the required torque values were recorded.

RESULTS

Finite element analysis revealed that under single-leg stance loading, the maximum Z-axis fragmentary displacements were 5.060 mm for ICCS, 4.028 mm for FNS, and 2.796 mm for PCCP. The maximum displacements of internal fixations were 4.545 mm for ICCS, 3.047 mm for FNS, and 2.559 mm for PCCP. Peak VMS values were 512.21 MPa for ICCS, 242.86 MPa for FNS, and 413.85 MPa for PCCP. Under increasing vertical loads applied to the artificial bones, the average vertical axial stiffness for the ICCS, FNS, and PCCP groups were 244.86 ± 2.84 N/mm, 415.03 ± 27.10 N/mm, and 529.98 ± 23.08 N/mm. For the torsional moment tests, the PCCP group demonstrated significantly higher torque values at 2°, 4°, and 6° compared with FNS and ICCS, with no significant difference between FNS and ICCS (P > 0.05).

CONCLUSIONS

Finite element analysis and artificial bone models indicated that PCCP offers the best compressive and rotational stability for fixing Pauwels type III femoral neck fractures, followed by FNS and then ICCS. No significant difference in rotational resistance was observed between FNS and ICCS in synthetic bones. Level of Evidence Level 5.

Finite Element Analysis of Six Internal Fixations in the Treatment of Pauwels Type III Femoral Neck Fracture

OBJECTIVE

The current investigation sought to utilize finite element analysis to replicate the biomechanical effects of different fixation methods, with the objective of establishing a theoretical framework for the optimal choice of modalities in managing Pauwels type III femoral neck fractures.

METHODS

The Pauwels type III fracture configuration, characterized by angles of 70°, was simulated in conjunction with six distinct internal fixation methods, including cannulated compression screw (CCS), dynamic hip screw (DHS), DHS with de-rotational screw (DS), CCS with medial buttress plate (MBP), proximal femoral nail anti-rotation (PFNA), and femoral neck system (FNS). These models were developed and refined using Geomagic and SolidWorks software. Subsequently, finite element analysis was conducted utilizing Ansys software, incorporating axial loading, torsional loading, yield loading and cyclic loading.

RESULTS

Under axial loading conditions, the peak stress values for internal fixation and the femur were found to be highest for CCS (454.4; 215.4 MPa) and CCS + MBP (797.2; 284.2 MPa), respectively. The corresponding maximum and minimum displacements for internal fixation were recorded as 6.65 mm for CCS and 6.44 mm for CCS + MBP. When subjected to torsional loading, the peak stress values for internal fixation were highest for CCS + MBP (153.6 MPa) and DHS + DS (72.8 MPa), while for the femur, the maximum and minimum peak stress values were observed for CCS + MBP (119.3 MPa) and FNS (17.6 MPa), respectively. Furthermore, the maximum and minimum displacements for internal fixation were measured as 0.249 mm for CCS + MBP and 0.205 mm for PFNA. Additionally, all six internal fixation models showed excellent performance in terms of yield load and fatigue life.

CONCLUSION

CCS + MBP had the best initial mechanical stability in treatment for Pauwels type III fracture. However, the MBP was found to be more susceptible to shear stress, potentially increasing the risk of plate breakage. Furthermore, the DHS + DS exhibited superior biomechanical stability compared to CCS, DHS, and PFNA, thereby offering a more conducive environment for fracture healing. Additionally, it appeared that FNS represented a promising treatment strategy, warranting further validation in future studies.

Given the encouraging results of biomechanical studies on femoral neck fractures, are locking plates more safe?

This current study compares the clinical and radiological outcomes of femoral neck fractures in young adults treated with either cannulated screws (CS) or proximal femoral locking plates (PFLP). We conducted a retrospective study in patients aged 18 to 60 years with femoral neck fractures and investigated medical records between January 2005 and December 2016. Patients were divided into two groups based on implants, screw and plate, used for fixation assigned. In addition, two groups were compared for their complications and functional outcomes, which were assessed with Harris Hip Score (HHS) and Parker Palmer mobility scores. Sixty-nine of 104 patients met the inclusion criteria. Forty patients were treated with cannulated screws, while 29 were treated with a proximal femoral locking plate. The two groups were comparable in terms of their perioperative variables. The overall complication rate (screw group, n = 10; plate group, n = 14) and non-union rate were significantly high in the plate group (p < 0.05). Other complications did not show statistically significant differences. The screw group had better functional outcomes than the plate group, where only the Parker-Palmer mobility score comparison was significant (p < 0.05). Poor reduction quality and Pauwels' type III fractures were statistically associated with high complication rates regardless of the implants used (p < 0.05). Although PFLP showed better outcomes in biomechanical studies than CSs, we observed poorer clinical results. Therefore, although some of our results appeared to be statistically significant, reduction quality should also be considered.

Comparison of rehabilitation outcomes between robot-assisted and freehand screw placement in treatment of femoral neck fractures: a systematic review and meta-analysis

PURPOSE

To compare the postoperative rehabilitation of femoral neck fractures treated with robot-assisted nailing and freehand nailing.

METHODS

We systematically searched the PubMed, EMBASE, Cochrane, China National Knowledge Infrastructure(CNKI), WanFang database, China Science and Technology Journal Database (VIP) and Web of Science databases to identify potentially eligible articles. Indispensable data such as the year of publication, country, study type, robot type, age, number of patients, sex distribution, study design, and outcome indicators were extracted. The outcome indicators of interest included healing rate, length of healing time, Harris score, operation time, frequency of X-ray fluoroscopy, frequency of guide pin insertion, and intraoperative blood loss. RevMan 5.4.1 was used for the meta-analysis.

RESULTS

Fourteen studies with 908 participants were included in this meta-analysis. The results showed that in terms of healing rate (SMD = 2.75, 95% CI, 1.03 to 7.32, P = 0.04) and Harris score (SMD = 2.27, 95% CI, 0.79 to 3.75, P = 0.003), robot-assisted screw placement technique scores were higher than the traditional freehand technique. Additionally, operative time (SMD = -12.72, 95% CI, -19.74 to -5.70, P = 0.0004), healing time (SMD = -13.63, 95% CI, -20.18 to -7.08, P < 0.0001), frequency of X-ray fluoroscopy (SMD = - 13.64, 95% CI, - 18.32 to - 8.95, P < 0.00001), frequency of guide pin insertion (SMD = - 7.95, 95% CI, - 10.13 to - 5.76, P < 0.00001), and intraoperative blood loss (SMD = - 17.33, 95% CI, - 23.66 to - 11.00, P < 0.00001) were lower for patients who underwent robotic-assisted screw placement than those for patients who underwent the conventional freehand technique.

CONCLUSION

Compared to the freehand nailing technique, robot-assisted nailing helps improve postoperative healing rates in patients with femoral neck fractures; shortens healing times; better restores hip function; reduces the number of intraoperative fluoroscopies, guides pin placements; reduces intraoperative bleeding; and increases perioperative safety.

Comparison of augmentation effects of medial buttress plate versus trochanteric lag screw in the cannulated screw fixation of Pauwels type III femoral neck fractures: A retrospective clinical study

OBJECTIVE

This study aimed to compare the effects of a medial buttress plate (MBP) or a trochanteric lag screw (TLS) to augment cannulated screws (CSs) in fixing Pauwels type III femoral neck fractures.

METHODS

This retrospective study included 58 patients (21 female, 37 male; mean age=46 years; age=19-64 years) treated by CSs for Pauwels type III femoral neck fractures from 2014 to 2017. All the patients were divided into 2 groups based on the internal fixation patterns: the MBP-augmented group (group A, n=26) and the TLS group (group B, n=32). The mean age was 47 (range=24-57) years in group A and 45 (range=19-64) years in group B. The operation time, intraoperative blood loss, reduction quality, Harris score, and postoperative complications were recorded and compared between both groups.

RESULTS

All patients were followed up for an average of 44.8 months in group A and 47.3 months in group B (P=.406). No significant difference was noted in reduction quality (P=1.000). However, group A had a longer operation time (100.2 vs. 64.3 minutes, P < .001) and greater intraoperative blood loss (153.1 vs. 30.0 mL, P < .001) than group B. At the final follow-up, the union rate was equal between group A (96.2%) and group B (90.6%) (P=.760). The mean bone union time was 21.6 weeks in group A and 23.6 weeks in group B (P=.431). The delayed union rate was lower in group A (0%) than in group B (15.6%) (P < .001). The incidence of postoperative complications in terms of implant failure (7.7% vs. 28.1%, P=.048) and femoral neck shortening (7.7% vs. 28.1%, P=.048) were lower in group A than in group B. No significant difference was noted in avascular femoral head necrosis (P=1.000) and the Harris score (P=.659) between the 2 groups.

CONCLUSION

In the surgical treatment of Pauwels type III femoral neck fractures, medial buttress plating can offer fewer complications but equal avascular femoral head necrosis rate and functional outcome compared to trochanteric screw application.

LEVEL OF EVIDENCE

Level III, Therapeutic study.

The effect of anteromedial support plate with three cannulated screws in the treatment of Pauwels type III femoral neck fracture in young adults

PURPOSE

This study is aimed to evaluate the clinical effects of anteromedial support plate combined with three cannulated screws on Pauwels type III femoral neck fractures in young adults.

METHODS

We conducted a retrospective study of 27 patients with Pauwels type III femoral neck fracture treated by anteromedial support plate combined with three cannulated screws. The results of fracture healing and complications for all patients were assessed by postoperative imaging examination. The Harris hip score was used to evaluate the functional outcome of the hip at the last follow-up.

RESULTS

The fracture union was achieved in 25 patients (92.6%). However, two patients required reoperation (two for nonunion). Early implant failure occurred in one patient, neck shortening in one patient and coxa vara in one patient. The excellent or good outcome of the Harris hip score was 96% for the 25 patients with satisfactory fracture union.

CONCLUSION

Our preliminary results indicate that anteromedial support plate combined with three cannulated screws is a good alternative in the treatment of Pauwels type III femoral neck fractures in young adults with high union rate and low incidence of complications including nonunion and avascular necrosis of the femoral head.

[Effectiveness of percutaneous compression plate fixation for femoral neck fractures]

Objective

To investigate the effectiveness of percutaneous compression plate (PCCP) fixation for femoral neck fracture.

Methods

A clinical data of 100 patients with femoral neck fractures who were treated with internal fixation were analyzed retrospectively. The fractures were fixed with the cannulated screws (CS) in 55 patients (CS group) and with the PCCP in 45 patients (PCCP group). There was no significant difference in gender, age, the cause of injury, the fracture type, complications, and disease duration between the two groups ( P>0.05). The quality of fracture reduction, bone resorption, screw slipping, femoral neck shortening, complications (nonunion, failure of fixation, and osteonecrosis of femoral head), and functional recovery of hip (Harris score) were compared between the two groups.

Results

All incisions healed by first intention. All patients were followed up 24-56 months, with an average of 30.7 months. The quality of fracture reduction was excellent in 26 cases, good in 18 cases, fair in 9 cases, and poor in 2 cases in CS group and excellent in 21 cases, good in 17 cases, fair in 4 cases, and poor in 3 cases in PCCP group, showing no significant difference between the two groups ( Z=-0.283， P=0.773). The incidence of nonunion in PCCP group was significantly lower than that in CS group ( P=0.046), and the fracture healing time in PCCP group was shorter than that in CS group ( t=2.155, P=0.034). There was no significant difference in the incidences of bone resorption, screw slipping, femoral neck shortening, failure of fixation, and osteonecrosis of femoral head between the two groups ( P>0.05). The overall complication rates were 27.27% (15/55) in CS group and 8.89% (4/45) in PCCP group, showing significant difference ( χ ²=5.435, P=0.020). The Harris score in PCCP group at 6 months after operation was significantly higher than that in CS group ( t=-2.073, P=0.041). However, there was no significant difference in the Harris score at 12, 18, and 24 months after operation between the two groups ( P>0.05).

Conclusion

Stable sliding compression of PCCP is benefit for the femoral neck fracture healing, especially shortening union.

Dynamic limited axial compression yields favorable functional outcomes in the fixation of Pauwels type-3 femoral neck fractures: A retrospective cohort study

PURPOSE

Pauwels type-3 femoral neck fractures are challenging injuries to manage with high rates of complications after internal fixation and no consensus has been reached regarding the optimal fixation construct. The current study aims to evaluate the effect of dynamic limited axial compression in parallel screws combined with medial buttress plate (SMBP) or lateral compression plate (LCP) fixation of Pauwels type-3 femoral neck fractures.

METHODS

We performed a retrospective analysis of 51 cases of Pauwels type-3 femoral neck fractures who were fixed by SMBP or LCP. Specifically, the screw fixing the femoral head in the buttress plate was omitted. Postoperative complications and functional outcomes were mainly studied.

RESULTS

With a mean follow-up of 19.9 months, the rate of neck shortening was higher in the LCP group than that in SMBP group (32.1% vs. 8.7%, p = 0.04). Neither nonunion nor avascular necrosis was observed in both groups. Good-to-excellent Harris hip score accounts for 95.2% in SMBP group and 89.3% in LCP group (p = 0.40). Moreover, older age, fracture comminution and compression plate fixation predispose to neck shortening.

CONCLUSION

Dynamic limited axial compression by SMBP or LCP fixation was effective to improve the functional outcome of patients with Pauwels type-3 femoral neck fractures.

A quantitative biomechanical study of positive buttress techniques for femoral neck fractures: a finite element analysis

Background:

Refractory femoral neck fractures cannot be anatomically reduced by closed traction reduction which may affect fracture healing. We evaluated the biomechanical effects of positive, negative, and anatomic reduction of various degrees of displacement in Pauwels I femoral neck fractures by a finite element analysis.

Methods:

Five reduction models of Pauwels type I femoral neck fracture were established using the Mimics 17.0 (Materialize, Leuven, Belgia) and Hypermesh 12.0 (Altair Engineering, Troy, MI, USA). According to the degree of fracture displacement, there were three models of positive support, an anatomic reduction model, and a negative 2 mm reduction model. Finite element analysis was conducted using the ABAQUS 6.9 software (Simulia, Suresnes, France). The von Mises stress distribution and the stress peak of internal fixation in different models, the displacement between fracture blocks, and the principal strain of the femoral neck cancellous bone model were recorded under the axial stress of 2100 N.

Results:

The peak von Mises stress on screw of each model was located at the thread of the screw tip. The peak von Mises stress was the lowest at the tip of the anatomic reduction model screw (261.2 MPa). In the positive 4 mm model, the von Mises stress peak was the highest (916.1 MPa). The anatomic reduction model showed the minimum displacement (0.388 mm) between fracture blocks. The maximum displacement was noted in the positive 4 mm model (0.838 mm). The displacement in the positive 3 mm model (0.721 mm) was smaller than that in the negative 2 mm model (0.786 mm). Among the five models, the strain area of the femoral neck cancellous bone was mainly concentrated around the screw hole, and the area around the screw hole could be easily cut.

Conclusions:

Compared with negative buttress for femoral neck fracture, positive buttress can provide better biomechanical stability. In Pauwel type I fracture of femoral neck, the range of positive buttress should be controlled below 3 mm as far as possible.

Finite element analysis of a new plate for Pauwels type III femoral neck fractures

Background

Method

Result

Conclusion