Biomechanical Comparison of 2 Methods of Intramedullary K-Wire Fixation of Transverse Metacarpal Shaft Fractures

Retro-Antegrade Technique in the Management of Severely Angulated Fourth and Fifth Metacarpal Neck Fractures: A Case Series

Background: This study introduces a novel method for the management of closed metacarpal neck fractures. Kirschner wires (K-wire) are introduced in a retrograde and the wires withdrawn through skin proximally at the base of the metacarpal. The fracture is reduced using traction and the reduction is maintained by antegrade advancement of the K-wires. The aim of this study is to report the outcomes of this technique. Methods: A total of 36 patients with severely angulated closed metacarpal neck fractures underwent reduction and fixation using this novel method from January 2017 to December 2020 in centres in Ireland and Saudi Arabia. We performed a retrospective review of these patients' clinical data examining their outcomes. Results: Six months postoperatively, all fractures demonstrated bony union and correction of angulation. All patients exhibited excellent range of motion (ROM) with no significant impairment of hand function. Conclusions: The method detailed here is a simple, minimally invasive and reliable technique that has not previously been described. It is suitable for use in the management of closed metacarpal neck fractures of the fourth and fifth metacarpal, with dorsal angulation greater than 60°. Level of Evidence: Level IV (Therapeutic).

[Translated article] Closed reduction and intramedullary fixation of fifth metacarpal neck fractures: Retrograde vs. anterograde technique. Prospective study

INTRODUCTION

The fifth metacarpal fracture is a frequent pathology that can cause deformity and functional impairment for the adequate grip of the hand. Reintegration into daily or working activities is related to the treatment received and rehabilitation. In fractures of the neck of the fifth metacarpal, internal fixation with a Kirschner's wire is a conventional treatment method with variants that affect its outcome.

AIM OF THE STUDY

To compare the functional and clinical results of the treatment of fifth metacarpal fracture with the use of retrograde vs. antegrade Kirschner wires.

MATERIAL AND METHODS

Comparative, longitudinal, prospective study at a third-level trauma centre in patients with a fifth metacarpal neck fracture, with clinical, radiographic and Quick DASH scale follow-up at the 3rd, 6th, and 8th postoperative week.

RESULTS

Sixty patients were included (58 men, 2 women), age of 29.63±10.15 years, with a fifth metacarpal fracture, treated by closed reduction and stabilisation with a Kirschner wire. The antegrade approach showed a metacarpophalangeal flexion range at 8 weeks of 89.11° (p<0.001; 95% CI [-26.81; -11.42]), a DASH scale value of 18.17 (p<0.001; 95% CI [23.45; 39.12]), and an average of 27.35 days to return to work (p=0.002; 95% CI [16.22; 62.14]), compared with the retrograde approach.

CONCLUSION

Stabilisation with antegrade Kirschner wire showed superior functional results, and metacarpophalangeal range of motion, compared to those operated via retrograde approach.

Closed reduction and intramedullary fixation of fifth metacarpal neck fractures: Retrograde vs. anterograde technique. Prospective study

INTRODUCTION

The fifth metacarpal fracture is a frequent pathology that can cause deformity and functional impairment for the adequate grip of the hand. Reintegration into daily or working activities is related to the treatment received and rehabilitation. In fractures of the neck of the fifth metacarpal, internal fixation with a Kirschner's wire is a conventional treatment method with variants that affect its outcome.

AIM OF THE STUDY

To compare the functional and clinical results of the treatment of fifth metacarpal fracture with the use of retrograde versus antegrade Kirschner wires.

MATERIAL AND METHODS

Comparative, longitudinal, prospective study at a third-level trauma center in patients with a fifth metacarpal neck fracture, with clinical, radiographic and Quick DASH scale follow-up at the 3rd, 6th, and 8th postoperative week.

RESULTS

Sixty patients were included (58 men, 2 women), age of 29.63±10.15 years, with a fifth metacarpal fracture, treated by closed reduction and stabilization with a Kirschner wire. The antegrade approach showed a metacarpophalangeal flexion range at 8 weeks of 89.11° (p<0.001; 95% CI [-26.81; -11.42]), a DASH scale value of 18.17 (p<0.001; 95% CI [23.45; 39.12]), and an average of 27.35 days to return to work (p=0.002; 95% CI [16.22; 62.14]), compared with the retrograde approach.

CONCLUSION

Stabilization with antegrade Kirschner wire showed superior functional results, and metacarpophalangeal range of motion, compared to those operated via retrograde approach.

Intramedullary Metacarpal Fracture Fixation: A Biomechanical Study of Screw Diameter and Comparison With Intramedullary Wire Stabilization

PURPOSE

Interest in intramedullary metacarpal fracture fixation (IMFF) with screws is increasing. However, the optimal screw diameter for fracture fixation is not yet established. In theory, larger screws should be more stable, but there is concern about long-term sequelae of larger metacarpal head defects and extensor mechanism injury created during insertion as well as implant cost. Therefore, the purpose of this study was to compare different diameter screws for IMFF to a popular and more cost-effective alternative of intramedullary wiring.

METHODS

Thirty-two cadaveric metacarpals were used in a transverse metacarpal shaft fracture model. Treatment groups consisted of IMFF with 3.0 × 60 mm, 3.5 x 60 mm, and 4.5 x 60 mm screws as well as 4 1.1-mm intramedullary wires. Cyclic cantilever bending was performed with the metacarpals mounted at 45° to simulate physiologic loading. Cyclical loading at 10, 20, and 30 N was performed to determine fracture displacement, stiffness, and ultimate force.

RESULTS

At 10, 20, and 30 N of cyclical loading, all screw diameters tested provided similar stability as measured by fracture displacement and were superior to the wire group. However, ultimate force under load to failure testing was similar between the 3.5- and 4.5-mm screws and superior to 3.0-mm screws and wires.

CONCLUSIONS

For IMFF, 3.0, 3.5, and 4.5-mm diameter screws provide adequate stability for early active motion and are superior to wires. When comparing the different screw diameters, 3.5- and 4.5-mm diameter screws offer similar construct stability and strength superior to the 3.0-mm diameter screw. Therefore, to minimize metacarpal head morbidity, smaller screw diameters may be preferable.

CLINICAL RELEVANCE

This study suggests that IMFF with screws is biomechanically superior to wires in cantilever bending strength in the transverse fracture model. However, smaller screws may be sufficient to permit early active motion while minimizing metacarpal head morbidity.

Biomechanical Modeling of Connecting Intermetacarpal K-Wires in the Treatment of Metacarpal Shaft Fractures

BACKGROUND

Clinical series have been published using the configuration of 2 intercarpal Kirschner wires (K-wires) adjacent to the fracture being connected, but biomechanical analysis is lacking. The objective of this pilot biomechanical study was to model and compare the effects of externally connecting 2 intermetacarpal K-wires for the stabilization of transverse metacarpal shaft fractures. Our research hypothesis was that the connected constructs would be stiffer than the unconnected K-wires.

METHODS

A 3-dimensional computer-based model of small finger transverse metacarpal fracture stabilization was designed with 3 transverse 1.1 mm K-wires being anchored to the adjacent metacarpal. Three arrangements were tested: all 3 K-wires in parallel, the middle K-wire angled toward the proximal wire, and the middle angled K-wire being rigidly fixed to the proximal K-wire. The proximal wire was proximal to the fracture. A finite element analysis was performed by applying a cantilever force of 100 N at the head of the metacarpal. The metacarpal was considered to be uniform in composition with parameters typical for human bone. Kirschner wire parameters for stainless steel were used. Force (N) versus displacement was measured.

RESULTS

The configuration with the middle angled K-wire being rigidly fixed to the proximal K-wire showed greater stiffness (12 N/mm) than nonattached constructs. The connected construct was 2.3 times more stiff than the unattached parallel construct and 2.5 times more stiff than angling the middle K-wire without attachment.

CONCLUSIONS

In a computer model simulation, our results show that attaching 2 K-wires adjacent to the fracture provides more than twice the stiffness of unconnected K-wires.

Treatment of isolated fourth metacarpal neck fractures using the closed reduction and percutaneous intermetacarpal and external fixation

BACKGROUND

The isolated fourth metacarpal neck fracture is uncommon, and the appropriate management is still debatable. The aim of this retrospective study was to introduce a closed reduction and percutaneously intermetacarpal K-wire fixation external technique to treat the isolated fourth metacarpal neck fracture.

METHODS

From October 2013 to January 2018, 21 patients with closed-isolated fourth metacarpal neck fractures (angulation ≥35°, rotation ≥5°, or shortening ≥5 mm) were treated with the closed reduction and percutaneous intermetacarpal and external fixation technique. Total active motion, grip strength of the hand, dorsal prominence, and patient satisfaction were assessed.

RESULTS

Follow-up lasted 28 months (range, 24-37 months). All patients obtained bone healing at a mean time of 5 weeks (range, 4-8 weeks). External fixation devices were removed when bone healing achieved. The mean total active motion reached 97.5% (range, 92.9%-100%) of opposite side. There were 18 excellent and 3 good results. The mean grip strength reached 98.4% (range, 96.2%-100%) of the opposite hands. Based on the 100-mm visual analogue scale, the mean dorsal prominence was 0 (range, 0 to 1). Based on the Short Assessment of Patient Satisfaction, the mean satisfaction score was 26 (range, 24 to 28).

CONCLUSIONS

The closed reduction and percutaneous intermetacarpal and external fixation technique is useful and reliable for treating the isolated fourth metacarpal neck fracture. The technique can effectively restore the fracture deformities and maintain the reduction stably, resulting in good hand function.

LEVEL OF EVIDENCE

Therapeutic study, Level IV.

Biomechanical comparison of intramedullary screw fixation, dorsal plating and K-wire fixation for stable metacarpal shaft fractures

We compared four methods of metacarpal shaft fixation: 2.2 mm intramedullary headless compression screw; 3.0 mm intramedullary headless compression screw; intramedullary K-wire fixation; and dorsal plate fixation. Transverse mid-diaphyseal fractures were created in 64 metacarpal sawbones and were assigned into four groups. Peak load to failure and stiffness were measured in cantilever bending and torsion. We found that dorsal plating had the highest peak load to failure. However, initial bending stiffness of the 3.0 mm intramedullary headless compression screw was higher than that of the dorsal plates. In torsion testing, dorsal plating had the highest peak torque, but there was no significant difference in torsional stiffness between the plate and intramedullary headless compression screw constructs. We concluded that intramedullary headless compression screw fixation is biomechanically superior to K-wires in cantilever bending and torsion; however, it is less stable than dorsal plating. In our study, the initial stability provided by K-wire fixation was sufficient to cope with expected loads in the early rehabilitation period, whereas dorsal plates and IHCS constructs provided stability far in excess of what is required.

Factors affecting healing following percutaneous intramedullary fixation of metacarpal fractures

Although percutaneous intramedullary nailing of metacarpal fractures is a straightforward and reliable technique, it is not without complications, and patients experience different outcomes. This study analyzed factors affecting fracture healing time and complication rates in patients who underwent percutaneous intramedullary fixation of metacarpal fractures.This study was a retrospective review of the 25 patients who underwent retrograde percutaneous Kirschner wire (K-wire) nailing for fracture of the metacarpal shaft or neck at a military hospital between May 2016 and October 2018. Correlation study and multiple regression analysis were performed to evaluate variables (age, smoking history in pack-years, body-mass index, fracture site, number of K-wires used) that affect time to bone union. Clinical features of patients with metacarpal neck fractures and those with metacarpal shaft fractures were also compared.The metacarpal shaft fractures (as opposed to metacarpal neck fractures) and higher number of K-wire used were associated with longer time to bone union. Mean union time was significantly longer for metacarpal shaft fracture (8.6 weeks) than for metacarpal neck fracture (6.1 weeks) and for patients who received more K-wires than for those who received less (regression coefficient 1.307). One patient suffered fixation failure and required revision operation, and another experienced superficial infection which was treated with intravenous antibiotics.Percutaneous intramedullary nailing is an effective technique for metacarpal fractures, but fracture site and number of K-wire used affect time to achieve bone union.

Comparative analysis of the effects of AO mini-plate and Kirschner wire pinning in the metacarpal fractures: A retrospective study

The aim of this study was to investigate the clinical effect of AO miniplate screw internal fixation and Kirschner wire (KW) in the treatment of metacarpal fractures.We retrospectively analyzed the clinical data of 590 metacarpal fracture patients admitted to our hospital from March 2016 to March 2019. Among them, 290 patients were treated with KWs; 300 were treated with AO microplate internal fixation. The clinical, radiological results, time of surgery, and complications were observed and compared between the 2 groups.The imaging characteristics and preoperative fracture types of the 2 groups were similar and comparable (P > .05). The operation time, length of hospital stay, and fracture healing time of AO group were shorter than those of KW group, and the differences were statistically significant (41.22 ± 7.23 vs 25.64 ± 6.29; 7.13 ± 2.38 vs 5.26 ± 1.71; 67.43 ± 22.01 vs 52.57 ± 17.46, P < .05). In addition, the incidence of postoperative complications in AO group was lower than that in KW group (8.3% vs 15.2%, P < .05). In terms of surgical knuckle extension, flexion, and total mobility (compared with the uninjured hand), patients in the AO plate group were significantly improved compared with patients in the KW group, and the difference was statistically significant (4 vs 10 degree; 19 vs 10 degree; 14 vs 29 degree, P < .05); The average degree of finger rotation deformity in AO plate group was significantly lower than that in KW group (1 vs 6 degree, P < .05). In terms of grip strength (compared with the healthy hand), the average grip strength of AO plate group was significantly higher than that of KW group (93% vs 83%, P < .05). Patients in the OA plate group had a lower Disabilities of the Arm, Shoulder and Hand score (P < .05).Compared with KW fixation, AO mini-plate and screw fixation for the metacarpal fracture has a better effect, which can effectively shorten the operation time and reduce the trauma to patients. It can provide patients with better stability and realize the early movement of the palm, promote fracture healing and joint function recovery; it can reduce the incidence of postoperative complications, which has certain safety. In addition, it can effectively reduce the risk of poor finger rotation.

Percutaneous reduction and fixation technique for 4th metacarpal shaft fracture

The objective of this retrospective study was to introduce a percutaneous reduction and intermetacarpal K-wire fixation technique for the treatment of the 4th metacarpal shaft fracture. From January 2014 to February 2017, 25 patients with isolated closed 4th metacarpal shaft fracture (angulation > 30°, rotation > 5°, or shortening > 5 mm) were treated by percutaneous reduction and internal fixation. Assessment comprised total active motion, grip strength, dorsal prominence, and patient satisfaction. Bone healing was achieved in all patients. At a mean follow-up of 28 months (range, 25-32 months), total active range of motion averaged 98% of contralateral values (range, 88%-100%). There were 20 excellent and 5 good results. Grip strength averaged 97% of contralateral values (range, 88%-100%). Mean dorsal prominence on a 100-mm visual analogue scale was 0 (range, 0-1). Mean satisfaction rating on the Short Assessment of Patient Satisfaction 26 (range, 22-28). Percutaneous reduction and intermetacarpal K-wire fixation is a useful technique for treating 4th metacarpal shaft fracture, achieving stable and reliable fixation, with good hand function.

A Single Intramedullary K-Wire Is Sufficient for the Management of Nonthumb Metacarpal Shaft Fractures

Objective

This study aims to evaluate the outcome after the internal fixation of diaphyseal metacarpal fractures by a single intramedullary K-wire.

Methods

In this prospective case series study, conducted from July 2017 to June 2019 in 23 adult patients with a single, unstable, diaphyseal metacarpal fracture, outcomes after internal surgical fixation using a single antegrade intramedullary K-wire were evaluated. The outcomes were evaluated by union rate, time to union, handgrip measurements at 6 and 12 months, and the modified Disabilities of the Arm, Shoulder, and Hand (DASH) score at 12 months.

Results

The study population consisted of 17 males and 6 females, with a mean patient age of 28.4 ± 8.5 years (range, 16–45 years). The median time to final follow-up was 14 ± 1.8 months (range: 12–24 months). The mean duration of the union was 7.3 ± 1.6 weeks (range: 5–11 weeks), with a union rate of 95.7% (22 cases). The mean handgrip strength was 68% ± 12.8% of the strength of the uninjured hand after 6 months and 92.7% ± 6.9% after 12 months. The mean modified DASH score was 2.6 ± 0.26 after 12 months (range: 0–5.8). There were no cases of malrotation or infection. In conclusion, using a single 1.8–2.0 mm K-wire gives excellent functional outcomes and union rate without significant complications when used to treat an unstable metacarpal shaft fracture.

Metacarpal shaft fixation: a biomechanical comparison of dorsal plating, lag screws, and headless compression screws

Background

Metacarpal shaft fractures are common and can be treated nonoperatively. Shortening, angulation, and rotational deformity are indications for surgical treatment. Various forms of treatment with advantages and disadvantages have been documented. The purpose of the study was to determine the stability of fracture fixation with intramedullary headless compression screws in two types of metacarpal shaft fractures and compare them to other common forms of rigid fixation: dorsal plating and lag screw fixation. It was hypothesized that headless compression screws would demonstrate a biomechanical stronger construct.

Methods

Five matched paired hands (age 60.9 ± 4.6 years), utilizing non-thumb metacarpals, were used for comparative fixation in two fracture types created by an osteotomy. In transverse diaphyseal fractures, fixation by headless compression screws (n = 7) and plating (n = 8) were compared. In long oblique diaphyseal fractures, headless compression screws (n = 8) were compared with plating (n = 8) and lag screws (n = 7). Testing was performed using an MTS frame producing an apex dorsal, three point bending force. Peak load to failure and stiffness were calculated from the load-displacement curve generated.

Results

For transverse fractures, headless compression screws had a significantly higher stiffness and peak load to failure, means 249.4 N/mm and 584.8 N, than plates, means 129.02 N/mm and 303.9 N (both p < 0.001). For long oblique fractures, stiffness and peak load to failure for headless compression screws were means 209 N/mm and 758.4 N, for plates 258.7 N/mm and 518.5 N, and for lag screws 172.18 N/mm and 234.11 N. There was significance in peak load to failure for headless compression screws vs plates (p = 0.023), headless compression screws vs lag screws (p < 0.001), and plates vs lag screws (p = 0.009). There was no significant difference in stiffness between groups.

Conclusion

Intramedullary fixation of diaphyseal metacarpal fractures with a headless compression screw provides excellent biomechanical stability. Coupled with lower risks for adverse effects, headless compression screws may be a preferable option for those requiring rapid return to sport or work.

Level of evidence

Basic Science Study, Biomechanics.

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.

Treatment for a Metacarpal Shaft Fracture using Locked Wire Fixator: A Case Report of New Surgical Technique

Introduction:

This article reports a case of metacarpal shaft fracture using a low-invasive simple locked wires fixator with a high degree of flexibility. A new surgical technique for this injury will also be presented.

Case Report:

A 27-year-old female with the right 3rd metacarpal shaft fracture caused by falling down while riding a bicycle. The patient was a professional ballet dancer and requested treatment enabling an early return to exercise and non-noticeable wound. Pins were percutaneously inserted antegradely and retrogradely to the metacarpal bone as intramedullary pinning, then were connected using locked wires fixator. Post-operative immobilization was not necessary. The locked wire fixator was removed 6 weeks after surgery. Postoperatively, there were no limitations of the range of motion of the finger joints and the operative scar was almost unrecognizable.

Conclusion:

This is a new breakthrough procedure facilitating. Furthermore, this surgical procedure may be selected as an esthetically useful method making a small wound because it can be percutaneously applied.

Intramedullary screw fixation for metacarpal shaft fractures: a biomechanical human cadaver study

Intramedullary cannulated compression screws have been introduced for the fixation of unstable metacarpal fractures. In the present study, this technique was compared with dorsal compression plating to evaluate its biomechanical performance in stabilizing metacarpal shaft fractures. In a first set of experiments, the biomechanical characteristics of the screws were analysed in an artificial bone model. In subsequent experiments, midshaft osteotomies were performed in human cadaver metacarpals, followed by plating or intramedullary screw osteosynthesis. The metacarpals were tested to failure in cantilever bending, following a stepwise increasing cyclic loading protocol. We found a significantly lower load at failure and a significantly lower number of cycles to failure in the intramedullary screw group, but both methods offered sufficient stability under these loads. With reference to published loads on the metacarpals during use of the hand, we conclude that intramedullary osteosynthesis yields sufficient strength and stiffness for early active motion. A difference in its fixation stability is noted compared with plate fixation, which may not be clinically relevant.

Locked wires fixator for fractures of the distal third of the radius and ulna in children

BACKGROUND

Prevention of redisplacement is an issue after the treatment of fractures of the distal third of the radius in children. In this study, we used a locked wires fixator for this type of fracture and achieved favorable treatment outcomes.

METHODS

The subjects were 8 children with fractures of the distal third of the radius (male: 7, female: 1, mean age: 9.0 years old) who underwent surgery with locked wires fixators and were able to be evaluated 12 months after surgery. Immobilization was not applied after surgery. The locked wires fixator or K-wire was removed when the bridging callus was observed on plain radiography 4-6 (mean 5.5) weeks after surgery in all patients. The presence of bone union, functional outcomes, and complications were investigated postoperatively.

RESULTS

All patients achieved bone union without redisplacement excellent function. The pin site infection was observed in two patients.

CONCLUSIONS

The locked wires fixator may be a new useful treatment method for fractures likely to cause postoperative redisplacement.

Transverse and oblique fractures of the diaphysis of the fifth metacarpal: surgical outcomes for antegrade intramedullary pinning versus combined antegrade and retrograde intramedullary pinning

The purpose of this study was to develop a technique allowing a faster return to previous activities after surgical treatment of short transverse and oblique fractures of the diaphysis of the fifth metacarpal. It consisted of an anterograde and retrograde centromedullary double pinning connected. Our series included 40 patients of average age 25 years including 2 women. In 20 cases (group I), an anterograde centromedullary pinning with a 1.6- or 2-mm pin was performed followed by a 6-week orthosis and then 2-week self-education. In 20 cases (group II), an anterograde and retrograde centromedullary double pinning was performed using 2 1.5-mm pins connected by a connector (MétaHUS^®, Arex™). A first pin was introduced into the canal antegrade, then the second retrograde. The 2 externalized pins were connected, and self-rehabilitation was encouraged. Mean tourniquet time was 14.75 min (group I) and 15.8 min (group II), respectively. At the last follow-up, the average pain was 0.35/10 and 0.2/10, the Quick DASH 0.68/100 and 0.57/100, the strength of the hand 94.65% and 94.35%, the active flexion MCP 98.5% and 99%, respectively. MCP active extension was 98.5% and 98.75%; the sick leave was 8.4 and 6.3 weeks. All fractures healed without recovery with 3 complications: 2 infections on pins, in each group, 1 CRPS1 (group I). Our results seem to show that the technique of anterograde and retrograde centromedullary double pinning connected in the treatment of short transverse and oblique fractures of the diaphysis of the fifth metacarpal gives results at least as good as the reference technique with a non-negligible socioeconomic advantage, a less time off work.

Headless Screw Fixation of Metacarpal Neck Fractures: A Mechanical Comparative Analysis

BACKGROUND

The purpose of this study was to compare the mechanical properties of metacarpal neck fracture fixation by headless compression screw (HCS) with that of Kirschner wire (KW) cross-pinning and locking plate (LP) fixation.

METHODS

A metacarpal neck fracture was created in 30 fourth-generation composite Sawbones metacarpal models. A volar-based wedge was removed using a custom jig to simulate a typical apex dorsal fracture, unstable in flexion. The models were divided into 3 equal groups based on the method of fixation: retrograde cross-pinning with two 1.2-mm KWs, 2.0-mm dorsal T-plate with six 2.0-mm locking screws (LP), and a 3.0-mm retrograde HCS. Models were fixed at the proximal end, mounted in a material testing machine, and loaded through a cable tensioned over the metacarpal head, simulating grip loading. Cyclic loading from 0 to 40 N was performed, followed by loading to failure. Load, displacement, and failure mode were recorded.

RESULTS

Stiffness of the HCS (7.3 ± 0.7 N/m) was significantly greater than the KW (5.8 ± 0.5 N/m) but significantly less than the LP (9.5 ± 1.9 N/m). With cyclic loading to 40 N, the LP exhibited significantly less displacement (0.2 ± 1.3 mm) compared with the HCS (2.5 ± 2.3 mm) and KW (2.8 ± 1.0 mm). Load to failure for the HCS (215.5 ±3 9.0 N) was lower than that of the KW (279.7 ± 100.3 N) and of the LP (267.9 ± 44.1 N), but these differences were not statistically significant.

CONCLUSIONS

The HCS provided mechanical fracture fixation properties comparable with KW fixation. The LP construct allowed significantly less displacement and had the highest strength of the 3 fixation methods.

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

Background

Fifth metacarpal neck fracture, also known as boxer’s fracture, is the most common metacarpal fracture. Percutaneous Kirschner-wire (K-wire) pinning has been shown to produce favorable clinical results. However, the fixation power of K-wires is a major concern. Plate fixation is also a surgical option, but it has the disadvantages of tendon adhesion, requirement of secondary surgery for removal of the implant, and postoperative joint stiffness. A fixation method that causes little soft tissue damage and provides high biomechanical stability is required for patients with fifth metacarpal neck fracture for whom surgical intervention is indicated. The present study proposed fixation using K-wires and a cerclage wire to treat fifth metacarpal neck fracture. The fixation power of this new method was compared with that of K-wires alone and plates.

Methods

We used a saw blade to create transverse metacarpal neck fractures in 16 artificial metacarpal bone specimens, which were then treated with four types of fixation as follows: (1) locking plate with five locking bicortical screws (LP group), (2) regular plate with five bicortical screws (RP group), (3) two K-wires (K group), and (4) two K-wires and a figure-of-eight cerclage wire (KW group). The specimens were tested by using cantilever bending testing on a material testing system. The stiffness of the four fixation types was determined by observing force–displacement curves. Finally, the Kruskal–Wallis test was adopted to process the data, and the Mann–Whitney exact test was performed to conduct paired comparison between the fixation types.

Results

The fixation strength levels of the four fixation approaches for treating fifth metacarpal neck fracture were ranked in a descending order of LP group (24.6 ± 5.1 N/mm, median ± interquartile range) > RP group (22.2 ± 5.8 N/mm) ≅ KW group (20.1 ± 3.2 N/mm) > K group (16.9 ± 3.0 N/mm).

Conclusion

The fixation strength of two K-wires was significantly higher when reinforcement was provided using a figure-of-eight cerclage wire. The strength of the proposed approach is similar to that of a regular plate with five bicortical screws but weaker than that of a locking plate with the same amount of bicortical screws. Cerclage wire-integrated K-wires can be an alternative method that avoids the excessive soft tissue dissection required for plating in open reduction internal fixation for fifth metacarpal neck fracture.

Treatment of fifth metacarpal neck fractures with antegrade single elastic intramedullary nailing

Background

The aim of this study was to investigate clinical outcomes of fifth metacarpal neck fractures using antegrade single elastic nail and to explore ideal puncture point to avoid iatrogenic ulnar nerve injury.

Methods

A single elastic nail with suitable diameter was used in 27 cases of fifth metacarpal neck fractures with dorsal angulation over 45°. An initial entry point was perforated at the ulnar-dorsal base of the metacarpal. The nail was inserted in an antegrade approach. The nail was usually removed at about 5 weeks postoperatively.

Results

At final follow up, all fractures proceeded to bony union. The mean total passive motion was 285° and the mean total active motion (TAM) was 270°. The mean angulation decreased from 50.2 ± 6.3° preoperatively to 7.4 ± 2.3° postoperatively (p < 0.001). The mean DASH-Score was 2.1 ± 3.6 points after surgery. Two cases of skin irritation and one case of the dorsal cutaneous branch of the ulnar nerve (DCBUN) injury were observed. Superficial wound infections were not observed.

Conclusions

Collectively, antegrade single elastic intramedullary nailing was a minimally invasive and reliable fixation technique for fifth metacarpal neck fractures with dorsal angulation over 45°. Appropriate puncture position helped to reduce nerve damage.