New fixation approach for transverse metacarpal neck fracture: a biomechanical study

The biomechanical evaluation of metacarpal fractures fixation methods during finger movements: a finite element study

Objective

This study used finite element analysis to simulate four commonly used fixation methods for metacarpal shaft oblique fractures during finger motion and evaluate their biomechanical performance. The aim was to provide evidence for clinically selecting the optimal fixation method, guiding early rehabilitation treatment, and reducing the risk of complications.

Methods

Finite element analysis simulated dynamic proximal phalanx motion (60° flexion, 20° extension, 20° adduction, and 20° abduction). We analysed stress, displacement, and distributions for dorsal plates, intramedullary nails, Kirschner wire, and screw fixation methods.

Results

At 60° of finger flexion and 20° of abduction, plate fixation demonstrated greater stability and minimal displacement, with a peak displacement of 0.19 mm; however, it showed higher stress levels in all motion states, increasing the risk of failure. The stability of the intramedullary nail was similar to that of the dorsal plate, with a maximum displacement difference of 0.04 mm, and it performed better than the dorsal plate during adduction of 20°. Kirschner wire showed the highest stress levels of 81.6 Mpa during finger flexion of 60°, indicating a greater risk of failure and unstable displacement. Screws had lower stress levels in all finger motion states, reducing the risk of failure, but had poorer stability. Stress and displacement distributions showed that the dorsal plate, intramedullary nail, and Kirschner wire mainly bore stress on the implants, concentrating near the fracture line and the proximal metacarpal. In contrast, the screws partially bore stress in the screw group. The anterior end of the metacarpal mainly hosted the maximum displacement.

Conclusion

This study demonstrates that under simulated finger motion states, the dorsal plate fixation method provides the best stability in most cases, especially during finger flexion and abduction. However, high stress levels also indicate a higher risk of failure. The intramedullary nail is similar to the dorsal plate in stability and performs better in certain motion states. Kirschner wire exhibits the highest risk of failure during flexion. Although screws have poorer stability in some motion states, they offer a lower risk of failure. These findings provide important reference and surgical selection strategies for treating metacarpal fractures.

Percutaneous transverse pinning for metacarpal fractures: a clinical trial

INTRODUCTION

Metacarpal fractures account for 25%-50% of all hand fractures and may negatively impact hand function and ability to work. Percutaneous transverse pinning of non-articular metacarpal fractures allows mobilisation immediately after the procedure.

METHODS

Between March 2017 and February 2022, 56 patients undergoing percutaneous transverse pinning for unstable metacarpal fractures were prospectively recruited. We investigated surgical outcomes in terms of Patient-rated Wrist/Hand Evaluation (PRWHE) and pre-and post-operative radiographic evaluation. The Student t-test was used to compare the means of PRWHE values after surgery. Statistical significance was set at p < 0.05.

RESULTS

The mean age was 40.21 ± 17.9 years (range of 16 to 86 years). The average operating time was 27.96 min. The mean follow-up period was 14.3 ± 6.4 months (from 2 to 41 months). The mean PRWHE score was 6.5 ± 1.8. None of the patients had clinically observable rotational deformities, and the functional outcomes were satisfactory.

CONCLUSION

Percutaneous transverse pinning for non-articular metacarpal fractures restores excellent function, and imaging results are satisfactory. Further high-quality clinical trials are required to validate these results on a larger scale.

LEVEL OF EVIDENCE

II, prospective cohort study.

Comparative Evaluation of the Efficacy of Combined Intramedullary Pinning with K-Wires Pinning in the Treatment of Fifth Metacarpal Neck Fractures versus Conventional Techniques-K-Wires Pinning and Intramedullary Pinning

Background and Objectives: Since the neck is the weakest part of the metacarpals, the most common metacarpal fracture is a neck fracture, a type which accounts for 38% of all hand fractures. Such fractures can be fixed using a variety of conventional techniques, including intramedullary pinning and K-wire pinning. However, conventional techniques involve complications, such as angulation, stiffness, and rotational deformity. The purpose of this study was to compare the usefulness of our new technique, combined intramedullary pinning with K-wire pinning (IPKP), with those of intramedullary pinning (IP) and K-wire pinning (KP). Materials and Methods: This was a single-center, randomized controlled trial conducted between January 2005 and April 2023. A total of 158 patients with acute displaced fractures of the fifth-metacarpal neck were randomly assigned to either the IPKP group (n = 48), the KP group (n = 60), or the IP group (n = 50). We radiographically evaluated angulation and shortening in three visits: pre-operatively, post-operatively, and at a 1-year follow-up. We clinically evaluated the ranges of motion and Quick-DASH scores to assess daily living performance and the cosmetic scores, using the SBSES score, to assess patients' satisfaction with their cosmetic outcomes. Results: The IPKP group was superior to the KP group and the IP group regarding radiographical and clinical assessments at the 1-year follow-up visit. The angulation was 15.7° (±7.7) in the KP group, 17.0° (±5.9) in the IP group, and 12.6° (±2.5) in the IPKP group (p < 0.001) at the 1-year follow-up visit. The shortening was 0.9 mm (±0.3) in the KP group, 1.4 mm (±0.2) in the IP group, and 0.4 mm (±0.1) in the IPKP group (m < 0.001) at the 1-year follow-up visit. The TAM was 272.6° (±17.5) in the KP group, 271.1° (±18.0) in the IP group, and 274.1° (±14.9) in the IPKP group (p = 0.42). Four patients (6.6%) in the KP group and two patients (4%) in the IP group were reported as having stiffness, while no patients were found to have stiffness in the IPKP group. The average Quick-DASH score was 2.3 (±0.5) in the KP group, 2.5 (±0.4) in the IP group, and 1.9 (±0.4) in the IPKP group (p > 0.05). The average cosmetic score was 3.7 (±1.2) in the KP group, 3.8 (±0.9) in the IP group, and 4.7 (±0.8) in the IPKP group (p < 0.001). A complication involving nonunion occurred in one case (1.6%) in the KP group, while there were three cases (6%) of rotational deformity in the IP groups. Conclusions: With the IPKP technique, accurate reduction can be achieved to improve hand function and cosmetic outcomes.

Biomechanical study of the fixation ability of the dorsal and volar locking plate for transverse metacarpal neck fractures

Metacarpal neck fracture is one of the most common types of hand fractures; the literature suggests that applying a bone plate on the dorsal side provides higher fixation strength than that provided by other fixation methods. However, bone plate fixation on the dorsal side may result in postoperative tendon adhesion. So far, no studies have investigated the fixation of metacarpal neck fractures on the volar side by using a bone plate. The objective of this study was to investigate the differences in the fixation results between bone plate fixation on the dorsal side and bone plate fixation on the volar side of the metacarpal in the case of a metacarpal neck fracture. A saw blade was used to create a transverse metacarpal neck fracture on 14 artificial metacarpal bone specimens. The specimens were divided into 2 groups depending on the fixation method: a volar locking plate (VLP) group and a dorsal locking plate (DLP) group. All specimens were subjected to a cantilever bending test on a material testing system, and a force-displacement curve was used to measure the yield force and stiffness, which served as an indicator of the fixation ability of the 2 fracture fixation methods. For the experimental results, the Mann-Whitney U test was used to compare the fixation abilities of the 2 fixation methods. In terms of yield force, the DLP group (266.9 ± 68.3 N) scored significantly higher than the VLP group (32.6 ± 2.7 N) (P < .05); expressed in terms of median, the DLP group scored 8.2 times higher than the VLP group. Similarly, in terms of stiffness, the DLP group (69.0 ± 13.4 N/mm, median ± interquartile range) scored significantly higher than the VLP group (12.9 ± 1.4 N/mm) (P < .05); expressed in terms of median, the DLP group scored 5.3 times higher than the VLP group. The fixation strength of volar bone plates is only about one-third of that of dorsal bone plates.

Treatment of fifth metacarpal neck fracture in adolescents with minimally invasive surgery: percutaneous Kirschner wire fixation versus elastic stable intramedullary nailing

OBJECTIVE

This retrospective study compared two minimally invasive surgical methods for fifth metacarpal neck fractures in adolescents: percutaneous Kirschner wire (K-wire) fixation and elastic stable intramedullary nailing (ESIN).

METHODS

This study involved 42 adolescents aged 11 to 16 years with fifth metacarpal neck fractures treated by either K-wire fixation (n = 20) or ESIN (n = 22). The palmar tilt angle and shortening were compared on radiographs preoperatively and 6 months postoperatively. Total active range of motion (TAM), the visual analogue scale score for pain, and the Disabilities of the Arm, Shoulder and Hand score for upper limb function were recorded at 5 weeks, 3 months, and 6 months postoperatively.

RESULTS

The mean TAM was significantly greater in the ESIN than K-wire group at all postoperative time points. The mean external fixation time was 2 weeks longer in the K-wire than ESIN group. One patient in the K-wire group developed infection. There was no statistically significant difference between the two groups in other postoperative outcomes.

CONCLUSIONS

ESIN fixation has the advantages of greater stability, better activity, a shorter external fixation time, and a lower infection rate than K-wire fixation in the treatment of fifth metacarpal neck fractures in adolescents.

Comparison of the fixation ability between lag screw and bone plate for oblique metacarpal shaft fracture

Background

For oblique metacarpal shaft fracture, if anatomical reduction is achieved through conservative cast immobilization rather than stable fixation, bone malrotation can easily occur, resulting in severe loss in hand prehensile function. However, whether bone plate fixation or only lag screw fixation is more preferable remains unclear. Few studies have evaluated whether screw fixation can provide biomechanical fixation strength similar to bone plate fixation.

Objective

We assessed the difference in fixation strength between fixtation with two lag screws and bone plate for oblique metacarpal shaft fractures.

Materials and methods

We created oblique metacarpal shaft fractures on 21 artificial bones and fixated them using (1) double lag screw (2LS group), (2) regular plate (RP group), or (3) locked plate (LP group). To obtain the force–displacement data, a cantilever bending test was conducted for each specimen through a material testing machine. One-way analysis of variance and a Tukey test were conducted to compare the maximum fracture force and stiffness of the three fixation methods.

Results

The maximum fracture force of the 2LS group (mean + SD: 153.6 ± 26.5 N) was significantly lower than that of the RP (211.6 ± 18.5 N) and LP (227.5 ± 10.0 N) groups (p < 0.001). However, no significant differences were discovered between the RP and LP groups. The coefficient of variation for the maximum fracture force of the 2LS group (17.3%) was more than twice as high as that of the RP (8.7%) and LP (4.4%) groups. In addition, the stiffness of the three fixation methods was similar.

Conclusion

Compared with bone plate fixation, double lag screw fixation yielded slightly lower maximum bearable fracture force but similar stiffness. Therefore, this technique could be used for treating oblique metacarpal shaft fractures. However, using double lag screw fixation alone is technically demanding and requires considerable surgical experiences to produce consistent results.

Comparison of the fixation ability of headless compression screws and locking plate for metacarpal shaft transverse fracture

Metacarpal shaft fractures are common hand fractures. Although bone plates possess strong fixation ability, they have several limitations. The use of headless compression screws for fracture repair has been reported, but their fixation ability has not been understood clearly.This study aimed to compare the fixation ability of locked plate with that of headless compression screw for metacarpal fracture repair.A total of 14 artificial metacarpal bones (Sawbones, Vashon, WA, USA) were subjected to transverse metacarpal shaft fractures and divided into 2 groups. The first group of bones was fixed using locked plates (LP group), whereas the second group was fixed using headless compression screws (HC group). A material testing machine was used to perform cantilever bending tests, whereby maximum fracture force and stiffness were measured. The fixation methods were compared by conducting a Mann-Whitney U test.The maximum fracture force of the HC group (285.6 ± 57.3 N, median + interquartile range) was significantly higher than that of the LP group (227.8 ± 37.5 N; P < .05). The median of the HC group was 25.4% greater. However, no significant difference in stiffness (P > .05) was observed between the HC (65.2 ± 24.6 N/mm) and LP (61.7 ± 19.7 N/mm) groups.Headless compression screws exhibited greater fixability than did locked plates, particularly in its resistance to maximum fracture force.

Bone plate fixation ability on the dorsal and lateral sides of a metacarpal shaft transverse fracture

Background

Metacarpal shaft fractures are a common hand trauma. The current surgical fixation options for such fractures include percutaneous Kirschner wire pinning and nonlocking and locking plate fixation. Although bone plate fixation, compared with Kirschner wire pinning, has superior fixation ability, a consensus has not been reached on whether the bone plate is better placed on the dorsal or lateral side.

Objective

The purpose of this study was to evaluate the fixation of locking and regular bone plates on the dorsal and lateral sides of a metacarpal shaft fracture.

Materials and methods

Thirty-five artificial metacarpal bones were used in the experiment. Metacarpal shaft fractures were created using a saw blade, which were then treated with four types of fixation as follows: (1) a locking plate with four locking bicortical screws on the dorsal side (LP_D); (2) a locking plate with four locking bicortical screws on the lateral side (LP_L); (3) a regular plate with four regular bicortical screws on the dorsal side (RP_D); (4) a regular plate with four regular bicortical screws on the lateral side (RP_D); and (5) two K-wires (KWs). All specimens were tested through cantilever bending tests on a material testing system. The maximum fracture force and stiffness of the five fixation types were determined based on the force–displacement data. The maximum fracture force and stiffness of the specimens with metacarpal shaft fractures were first analyzed using one-way analysis of variance and Tukey’s test.

Results

The maximum fracture force results of the five types of metacarpal shaft fracture were as follows: LP_D group (230.1 ± 22.8 N, mean ± SD) ≅ RP_D group (228.2 ± 13.4 N) > KW group (94.0 ± 17.4 N) > LP_L group (59.0 ± 7.9 N) ≅ RP_L group (44.5 ± 3.4 N). In addition, the stiffness results of the five types of metacarpal shaft fracture were as follows: LP_D group (68.7 ± 14.0 N/mm) > RP_D group (54.9 ± 3.2 N/mm) > KW group (20.7 ± 5.8 N/mm) ≅ LP_L group (10.6 ± 1.7 N/mm) ≅ RP_L group (9.4 ± 1.2 N/mm).

Conclusion

According to our results, the mechanical strength offered by lateral plate fixation of a metacarpal shaft fracture is so low that even KW fixation can offer relatively superior mechanical strength; this is regardless of whether a locking or nonlocking plate is used for lateral plate fixation. Such fixation can reduce the probability of extensor tendon adhesion. Nevertheless, our results indicated that when lateral plate fixation is used for fixating a metacarpal shaft fracture in a clinical setting, whether the mechanical strength offered by such fixation would be strong enough to support bone union remains questionable.

Effect of a figure-of-eight cerclage wire with two Kirschner wires on fixation strength for transverse metacarpal shaft fractures: an in vitro study with artificial bone

BACKGROUND

Metacarpal shaft fractures are a common type of hand fracture. Despite providing strong fixation strength, plate fixation has numerous shortcomings. Concerning internal fixation with Kirschner wires (K-wires), although this approach is frequently used to treat metacarpal shaft fractures, the lack of functional stability may result in fixation failure.

OBJECTIVE

To evaluate the effect of figure-of-eight cerclage wire on fixation for transverse metacarpal shaft fractures using two K-wires.

MATERIALS AND METHODS

We used a saw blade to create transverse metacarpal shaft fractures in 14 fourth-generation artificial third metacarpal bones (Sawbones, Vashon, WA, USA), which were assigned to groups undergoing fixation with two K-wires (KP) or with two K-wires and figure-of-eight cerclage wire (KP&F8). All specimens were subjected to material testing, specifically cantilever bending tests. The maximum fracture force and stiffness of the two fixation types were determined on the basis of the force-displacement data. The Mann-Whitney U test was used to compare between-group differences in maximum fracture force and stiffness.

RESULTS

The maximum fracture force of the KP group (median ± interquartile range = 97.30 ± 29.70 N) was significantly lower than that of the KP&F8 group (153.2 ± 69.50 N, p < 0.05; Figure 5a), with the median of the KP&F8 group exceeding that of the KP group by 57.5%. Similarly, stiffness was significantly lower in the KP group (18.14 ± 9.84 N/mm) than in the KP&F8 group (38.25 ± 23.49 N/mm; p < 0.05; Figure 5b), with the median of the KP&F8 group exceeding that of the KP group by 110.9%.

CONCLUSION

The incorporation of a figure-of-eight cerclage wire increased the maximum fracture force and stiffness by 57.5 and 110.9%, respectively, compared with those achieved in standard two K-wire fixation. Therefore, hand surgeons are advised to consider the proposed approach to increase fixation strength.

Effect of oblique headless compression screw fixation for metacarpal shaft fracture: a biomechanical in vitro study

Background

Metacarpal shaft fracture is a common fracture in hand trauma injuries. Surgical intervention is indicated when fractures are unstable or involve considerable displacement. Current fixation options include Kirschner wire, bone plates, and intramedullary headless screws. Common complications include joint stiffness, tendon irritation, implant loosening, and cartilage damage.

Objective

We propose a modified fixation approach using headless compression screws to treat transverse or short-oblique metacarpal shaft fracture.

Materials and methods

We used a saw blade to model transverse metacarpal neck fractures in 28 fresh porcine metacarpals, which were then treated with the following four fixation methods: (1) locked plate with five locked bicortical screws (LP group), (2) regular plate with five bicortical screws (RP group), (3) two Kirschner wires (K group), and (4) a headless compression screw (HC group). In the HC group, we proposed a novel fixation model in which the screw trajectory was oblique to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; thus, the screw did not damage the articular cartilage. The specimens were tested using a modified three-point bending test on a material testing system. The maximum fracture forces and stiffness values of the four fixation types were determined by observing the force–displacement curves. Finally, the Kruskal–Wallis test was adopted to process the data, and the exact Wilcoxon rank sum test with Bonferroni adjustment was performed to conduct paired comparisons among the groups.

Results

The maximum fracture forces (median ± interquartile range [IQR]) of the LP, RP, HC, and K groups were 173.0 ± 81.0, 156.0 ± 117.9, 60.4 ± 21.0, and 51.8 ± 60.7 N, respectively. In addition, the stiffness values (median ± IQR) of the LP, HC, RP, and K groups were 29.6 ± 3.0, 23.1 ± 5.2, 22.6 ± 2.8, and 14.7 ± 5.6 N/mm, respectively.

Conclusion

Headless compression screw fixation provides fixation strength similar to locked and regular plates for the fixation of metacarpal shaft fractures. The headless screw was inserted obliquely to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; therefore the articular cartilage iatrogenic injury can be avoidable. This modified fixation method may prevent tendon irritation and joint cartilage violation caused by plating and intramedullary headless screw fixation.

Controlled active exercise after open reduction and internal fixation of hand fractures

Background

Hand fractures can be treated using various operative or nonoperative methods. When an operative technique utilizing fixation is performed, early postoperative mobilization has been advocated. We implemented a protocol involving controlled active exercise in the early postoperative period and analyzed the outcomes.

Methods

Patients who were diagnosed with proximal phalangeal or metacarpal fractures of the second to fifth digits were included (n=37). Minimally invasive open reduction and internal fixation procedures were performed. At 3 weeks postoperatively, controlled active exercise was initiated, with stress applied against the direction of axial loading. The exercise involved pain-free active traction in three positions (supination, neutral, and pronation) between 3 and 5 weeks postoperatively. Postoperative radiographs and range of motion (ROM) in the interphalangeal and metacarpophalangeal joints were analyzed.

Results

Significant improvements in ROM were found between 6 and 12 weeks for both proximal phalangeal and metacarpal fractures (P<0.05). At 12 weeks, 26 patients achieved a total ROM of more than 230° in the affected finger. Postoperative radiographic images demonstrated union of the affected proximal phalangeal and metacarpal bones at a 20-week postoperative follow-up.

Conclusions

Minimally invasive open reduction and internal fixation minimized periosteal and peritendinous dissection in hand fractures. Controlled active exercise utilizing pain-free active traction in three different positions resulted in early functional exercise with an acceptable ROM.

Comparing the Efficacy and Safety of Metacarpal Neck Fracture Treatments: A Systematic Review and Network Meta-Analysis

Purpose

Metacarpal neck fractures may perform well without operative intervention, but the current literature on this topic is fragmented and guidance on managing these injuries needs further refinement. We conducted a systematic review and network meta-analysis to provide a comprehensive evaluation of the various treatments available for these injuries.

Methods

We searched 3 electronic databases and included any study comparing interventions for metacarpal neck fractures. We conducted a Bayesian network meta-analysis for each outcome.

Results

We identified a total of 14 studies comparing: antegrade (AIMP) or retrograde (RIMP) intramedullary pinning, buddy strapping, transverse pinning (TP), functional bracing, plating, retrograde cross-pinning, a combination of retrograde cross-pinning and plating, and placement of an orthosis or casting. Although the results were not statistically significant, the effect estimates suggested more favorable pain reduction and functional improvement with AIMP compared with nonsurgical therapies and RIMP in the short term (3 months or less). However, differences between interventions at later follow-up were less extreme; data on short-term pain and function with surgical options outside AIMP and RIMP were unavailable. In addition, compared with both plating and TP, AIMP was associated with significantly higher risks for implant migration and neurological events. There were contrasting findings in union-related outcomes. Plating showed the earliest time to union (not statistically significant) but TP demonstrated the lowest risk for a delayed union.

Conclusions

This review demonstrated that although AIMP may be a viable surgical option for early symptomatic relief after a metacarpal neck fracture, it may also be associated with a greater likelihood of certain postoperative complications. Clinicians should consider patient preferences for the time frame of symptomatic relief when selecting the optimal treatment, and patients should weigh the advantages and disadvantages of each available option, especially when considering invasive surgery. Considering the lack of high-quality primary research investigating these interventions, future studies are needed to make more definitive conclusions.

Type of study/level of evidence

Therapeutic II.