Antegrade Intramedullary Screw Fixation: A Novel Approach to Metacarpal Fractures

Cost Comparison of Intramedullary Screw Fixation Versus Open Reduction and Internal Fixation With Plate and Screw Technique for Metacarpal Fractures

BACKGROUND

Intramedullary screw (IMS) fixation for metacarpal fractures is a relatively new fixation technique in comparison to plate and screw constructs. Our hypothesis evaluated whether IMS fixation for metacarpal fractures results in lower overall health care-associated costs in comparison to open reduction and internal fixation (ORIF).

METHODS

A retrospective review of patients undergoing IMS fixation for metacarpal fractures at a single center during 2018 to 2022 was conducted. Health care-associated costs included primary operative costs (surgical time and implant(s)) and postoperative costs (therapy, splinting, and radiology). Costs were compared with age-matched and fracture pattern-matched controls who underwent ORIF with plate and screw construct. Subgroup analysis of cost outcomes excluding outliers was completed.

RESULTS

Eight subjects met the inclusion criteria and matched with an ORIF group. Primary operative costs were significantly higher in the ORIF group (mean difference of $1830, 95% CI: $1006 to $2653) The cost of an IMS at our institution was $584, whereas the average cost for plate and screw construct was $2538 (mean difference of $1953, 95% CI: $1665 to $2243). Total surgical costs were on average $3784 more for the ORIF group (95% CI: $2869 to $4700). There was no significant difference in outpatient follow-up costs (95% CI: -$441 to $3180). Total overall costs were significantly lower for the IMS group (95% CI: $2693 to $6513).

CONCLUSIONS

Total primary operative costs and overall health care-associated costs for IMS fixation of metacarpal fractures is significantly lower than ORIF. There was no statistical difference in follow-up care costs. To better determine the indirect costs for patients, high-powered prospective studies will be required.

Complications Following Intramedullary Screw Fixation for Metacarpal Fractures: A Systematic Review

PURPOSE

There has been a recent increase in the use of intramedullary screws (IMS) for the surgical treatment of metacarpal fractures. While IMS fixation has been shown to produce excellent functional outcomes, postoperative complications have yet to be fully explored in a comprehensive way. This systematic review quantified the incidence, treatment, and results of complications following IMS fixation for metacarpal fractures.

METHODS

A systematic review was performed using PubMed, Cochrane Central, EBSCO, and EMBASE databases. All clinical studies that documented IMS complications following metacarpal fracture fixation were included. Descriptive statistics were analyzed for all available data.

RESULTS

Twenty-six studies were included: 2 randomized trials, 4 cohort studies, 19 case series, and 1 case report. Among the 1,014 fractures studied, 47 complications were reported across all studies (4.6%). Stiffness was the most common, followed by extension lag, loss of reduction, shortening, and complex regional pain syndrome. Other complications included screw fracture, bending, and migration; early-onset arthrosis; infection; tendon adhesion; hypertrophic scar; hematoma; and nickel allergy. Eighteen of the 47 (38%) patients with complications underwent revision surgery.

CONCLUSIONS

Complications following IMS fixation of metacarpal fractures are relatively uncommon.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Intramedullary Screw Fixation of Metacarpal and Phalangeal Fractures

Metacarpal and phalangeal fractures are the second and third most common hand and wrist fractures seen in the emergency department. There are a multitude of operative fixation methods for metacarpal and phalangeal fractures, including closed reduction percutaneous pinning, open reduction internal fixation, external fixation, and intramedullary screw fixation. Although intramedullary fixation is a relatively new surgical technique, it is gaining in popularity as it allows patients to resume range of motion early in the postoperative period with excellent clinical outcomes.

Anterograde Intramedullary Headless Compression Screw for Managing Extra-articular Thumb Metacarpal Base Fracture: Technique and Report

Extra-articular base fractures of the thumb are typical in hand surgeon practice. Nonoperative methods (spica) and operative methods are available for its management. There are operative methods described, such as plate and screws, Kirschner wires, and intramedullary screws. However, there is only a retrograde technique described. This study aims to present a new technique of an anterograde intramedullary headless compression screw to manage the extra-articular thumb metacarpal base fracture. This minimally invasive method allows an early range of motion and does not cross the articular surface of the thumb. This alternative fixation method has the advantage of low damage to soft tissues and good functional outcomes.

Ideal Length and Diameter for Intramedullary Screw Fixation of Metacarpal Fractures: A Biomechanical Study

Purpose

This biomechanical study evaluated the effect of intramedullary screw diameter and length relative to 3-point bending force and torsional force when used to stabilize metacarpal shaft fractures.

Methods

Transverse osteotomies were made in the proximal metacarpal shaft in 36 middle finger metacarpal fourth-generation composite Sawbones. To compare screw diameters, antegrade intramedullary screws of 30-mm length were placed in 6 metacarpals, which included 4.7-mm Acutrak 2, Standard Acutrak 2 (4.0 mm), and Mini-Acutrak 2 (3.5 mm) screws. To compare screw lengths, metacarpals were fixated with Standard Acutrak 2 screws of 26, 30, or 34 mm in length, with screw tips bypassing the osteotomy by 6, 10, or 14 mm, respectively. A 6 degrees of freedom robot was used for torsional and 3-point bending testing.

Results

Increasing screw diameter demonstrated significant differences in both 3-point bending and torsional strengths. Maximum torsional loads were 69 Ncm (4.7-mm Acutrak 2), 45 Ncm (Standard Acutrak 2), and 27 Ncm (Mini-Acutrak 2) (P < .05). Loads to failure in the 3-point bending tests were 916 N (4.7-mm Acutrak 2), 713 N (Standard Acutrak 2), and 284 N (Mini-Acutrak 2) (P < .05). Differing screw lengths demonstrated significant differences with maximum torsional loads when comparing the 26-mm screws (22 Ncm) with 30- and 34-mm screws (45 and 55 Ncm, respectively) (P < .05). The 3-point dorsal bending strengths were significantly different between the 26-mm screws (320 N) and 30- and 34-mm screws (713 N and 702 N, respectively) (P < .05).

Conclusions

The results demonstrated significantly higher torsional strength and resistance to 3-point bending with larger intramedullary screw diameters. Further, when selecting the intramedullary screw length, the screw tip should pass at least 10 mm beyond the fracture.

Clinical Relevance

This study provided biomechanical evidence to guide surgeons in selecting intramedullary screw diameter and length for treating metacarpal fractures.

Headless Compression Screw for Metacarpal Nonunion: Description of a New Technique and Report of 4 Cases

Nonunion is a rare complication of metacarpal fractures and is usually associated with compound, open fractures with tissue loss and infection, or after failed surgical treatment. Repair by rigid osteosynthesis with plate and screws combined with autologous bone grafting has always been the treatment of choice for most patients. Such method allows early motion, although it has been proven that the presence of hardware may cause local soft tissue irritation. Often, hardware removal and tendon releases are necessary. We describe an original technique with a fixation method for the treatment of metacarpal nonunions, considering the excellent results attained with an intramedullary, headless screw for metacarpal fracture fixation. We report a series of three cases that evolved to bone healing with excellent clinical, functional, and radiographic outcomes.

Intramedullary Screw Fixation Comprehensive Technique Guide for Metacarpal and Phalanx Fractures: Pearls and Pitfalls

Background:

Phalangeal and metacarpal fractures are the second and third most common upper extremity fractures after distal radius fractures with varying methods of fixation techniques. Intramedullary screw fixation is an increasingly preferred method of fixation. Benefits include early range of motion, faster recovery, limited dissection, and reduced complications. Improper technique, which is readily avoidable, can lead to suboptimal results.

Methods:

A review of recent literature on current techniques aims to summarize the biomechanics of intramedullary screw fixation and outline appropriate technique of placing headless compression screws for metacarpal and phalangeal fractures.

Results:

We discuss through images and videos the indications, preoperative workup, and technical pearls and pitfalls to encourage surgeons to add this technique to their armamentarium and improve outcomes.

Conclusions:

intrameduallry screw fixation is a powerful option for metacarpal and phalanx fixation that allows rigid stability, enabling early return of function with excellent rates of union and total active motion. With knowledge of technical pearls presented in this article, common mistakes can be avoided to improve efficiency of screw placement and optimize patient outcomes.

Evaluation of Antegrade Intramedullary Compression Screw Fixation of Metacarpal Shaft Fractures in a Cadaver Model

PURPOSE

Surgical options for displaced metacarpal shaft fractures include the use of Kirschner wires, plates and screws, and most recently, intramedullary headless compression screws (IMHCS), which have been reported using only retrograde insertion through the metacarpal head. We evaluated IMHCS fixation of metacarpal shaft fractures through an antegrade approach in a cadaver model.

METHODS

We performed antegrade placement of IMHCS in 10 cadaver hands including all 5 digits (total of 50). Displaced transverse proximal metacarpal shaft fractures were created and reduced with a retrograde guidewire from the metacarpal head across the shaft fracture and exiting the metacarpal base. This was retrieved through a 6-mm dorsal wrist incision and overdrilled before the placement of a 4.1-mm-diameter IMHCS in the ring finger and a 4.7-mm screw in all other metacarpals. After IMHCS placement, carpometacarpal (CMC) joint violation was measured along with the optimal starting point for the guidewire on the metacarpal head relative to the dorsal cortex.

RESULTS

In all 50 metacarpals, we achieved successful fracture reduction and fixation without violating the extensor mechanism at the wrist. Our retrograde guidewire entry point through the metacarpal head ranged from 4.2 to 4.7 mm volar to the dorsal cortex. The actual area of CMC joint violated by IMHCS placement was largest in the index CMC joint (4.9%), followed by the middle (3.7%), little (2.9%), ring (0.5%), and thumb joints (0.2%).

CONCLUSIONS

Placement of IMHCS through an antegrade approach from the CMC joint can be performed effectively for all transverse metacarpal fractures, including the thumb, using a limited incision. There is minimal violation of the articular surfaces of the trapezium, capitate, and hamate for the thumb, middle, ring, and little metacarpals.

CLINICAL RELEVANCE

Antegrade IMHCS fixation successfully avoids the potential morbidity of creating a metacarpal head articular surface or extensor mechanism defect at the metacarpophalangeal joint seen with the retrograde approaches.

An Anatomical Study of Metacarpal Morphology Utilizing CT Scans: Evaluating Parameters for Antegrade Intramedullary Compression Screw Fixation of Metacarpal Fractures

PURPOSE

This study evaluated metacarpal morphology for antegrade placement of intramedullary headless compression screws (IMHCS) for metacarpal fracture fixation.

METHODS

We analyzed 100 hand computed tomography scans to quantify cortical thickness, intramedullary diameter, and metacarpal lengths. In addition, dorsal or ulnar overhang of the metacarpals over their respective carpal bones was measured. We also predicted optimal entry points for guidewire placement at the metacarpal head.

RESULTS

The ring finger metacarpal had the narrowest medullary canal width (coronal, 2.8 mm; sagittal, 3.5 mm). Not counting the thumb, the little finger metacarpal had the widest midshaft medullary width of 4.1 mm in the coronal plane and the middle metacarpal was widest in the sagittal plane with canal width of 3.9 mm. On average, there was maximal dorsal overhang at the base of the middle metacarpal (4.2 mm) and maximal ulnar overhang at the base of the small metacarpal (3.9 mm). The optimal entry point for guidewire placement over each metacarpal head was approximately 3.5 to 3.8 mm volar to the dorsal cortex.

CONCLUSIONS

Minimum IMHCS diameters of 3.5 mm for the ring and 4.0 mm for the index, middle and little fingers are necessary to achieve interference fit within the medullary canal. Minimum screw lengths of 38 mm would be needed to ensure 6 mm fixation past the midshaft of the metacarpals. Antegrade IMHCS for fixation of proximal metacarpal fractures may be most feasible with thumb, middle, and little finger metacarpals because there was larger dorsal or ulnar overhang to allow screw placement without violating the carpometacarpal joints.

CLINICAL RELEVANCE

Our analysis provides a reference guide for intramedullary screw sizes for each metacarpal of the hand to achieve interference fit with fracture fixation. Furthermore, the dorsal and ulnar overhangs of the metacarpal bases suggest the practicality of antegrade IMHCS fixation.