Clinical considerations in intramedullary headless screw fixation of metacarpal and proximal phalanx fractures

Abstract

Intramedullary headless screw (IMHS) fixation has gained increasing acceptance as a minimally invasive option for extra-articular metacarpal and proximal phalanx fractures. Recent prospective studies and systematic reviews demonstrate high union rates, favorable functional outcomes, and low complication incidence, particularly in diaphyseal and neck fractures of skeletally mature patients. The technique offers key advantages: Stable intramedullary fixation, preserved soft-tissue integrity, short operative times, and early mobilization without routine splinting. However, successful application depends on careful patient selection, precise guidewire placement to avoid rotational malalignment, appropriate implant choice, and meticulous protection of articular cartilage and extensor tendons. Comparative analyses indicate that IMHS achieves equivalent or superior functional recovery and significantly lower reoperation rates compared with Kirschner wire (K-wire) and plate-and-screw fixation in selected fracture patterns, though concerns persist regarding articular cartilage violation, extensor tendon irritation, and the technical learning curve. Cost and implant availability remain barriers in resource-limited settings. This Opinion Review synthesizes current evidence on biomechanical principles, indications, surgical techniques, rehabilitation protocols, and the complication profile of IMHS fixation. Comparative outcomes against K-wires and plating are discussed, along with economic considerations. Drawing on the available literature and our clinical experience, we present our perspectives on optimal patient selection, technical refinements, and priority areas for future research.

Key Words: Metacarpal fracture; Proximal phalanx fracture; Intramedullary headless screw; Hand fracture fixation; Minimally invasive surgery; Wide-awake local anesthesia

Core Tip: Intramedullary headless screw fixation represents a minimally invasive and mechanically reliable option for selected extra-articular metacarpal and proximal phalanx fractures, enabling early unrestricted mobilization with low complication rates. Evidence from recent meta-analyses confirms lower reoperation rates and superior Disabilities of the arm, shoulder and hand scores compared with Kirschner wires and plating. Success depends on meticulous patient selection, central guidewire technique, and structured rehabilitation. Long-term multicenter studies are needed to confirm durability and fully define indications.

INTRODUCTION

Metacarpal and proximal phalanx fractures represent a substantial proportion of upper extremity injuries, accounting for up to 10% of all skeletal injuries encountered in emergency departments[1]. They predominantly affect young, working-age individuals in their most productive years, with metacarpal fractures alone accounting for approximately 30%-40% of all hand fractures[2]. These injuries can result in pain, deformity, rotational malalignment, and significant functional impairment when managed suboptimally, with important socioeconomic consequences when return to work or daily activities is delayed[3]. Surgical fixation is generally indicated for unstable, displaced, or rotationally malaligned fractures to restore anatomical alignment, maintain stability, and facilitate early mobilization[4,5].

Over the past decades, three principal surgical fixation strategies have been adopted for metacarpal and proximal phalanx fractures: Percutaneous Kirschner wire (K-wire) fixation, open reduction and plate-and-screw constructs, and recently intramedullary headless screw (IMHS) fixation[6]. Each strategy carries distinct advantages and trade-offs in terms of mechanical stability, soft-tissue preservation, and rehabilitation potential, and the optimal choice depends on fracture pattern, bone quality, soft-tissue status, patient demands, and available resources[6].

Percutaneous K-wire fixation remains widely utilized because of its technical simplicity, low implant cost, and broad familiarity among orthopedic and hand surgeons[4]. K-wires can be inserted percutaneously through small stab incisions, providing satisfactory stability for many extra-articular fracture patterns. However, traditional K-wire constructs frequently require postoperative immobilization to maintain reduction, delaying active motion and predisposing to joint stiffness[4,6]. Furthermore, K-wire fixation carries well-documented risks of pin-tract infection, pin loosening or migration, loss of reduction, and the need for a secondary procedure for hardware removal[7]. These limitations are particularly relevant in patients whose occupation or lifestyle demands rapid functional recovery.

Plate-and-screw fixation offers an alternative that provides rigid stability, allowing earlier mobilization and more predictable maintenance of anatomical alignment, especially in comminuted, segmental, or complex fracture patterns[4]. Dorsal plating enables direct visualization of the fracture site and strong fixation tolerating early active motion and aggressive rehabilitation. Nevertheless, these benefits come at the cost of more extensive soft-tissue dissection, disruption of the extensor mechanism, and risks of tendon adhesions, hardware prominence, and postoperative stiffness[8]. Even with low-profile implants, extensor tendon irritation and the need for subsequent hardware removal remain important concerns, particularly over the proximal phalanx where the soft-tissue envelope is thin[8].

In recent years, IMHS fixation has emerged as a minimally invasive alternative aiming to combine stable fixation with soft-tissue preservation[9]. By placing a headless compression screw within the medullary canal, IMHS constructs provide axial stability and fracture compression while minimizing periosteal disruption and preserving extensor tendon gliding surfaces[10]. Biomechanical investigations demonstrate that intramedullary screws can achieve favorable load-to-failure characteristics and torsional resistance comparable to dorsal plating in selected metacarpal neck and shaft fracture patterns[10,11]. The percutaneous approach also facilitates shorter operative times and compatibility with wide-awake local anesthesia no tourniquet (WALANT) technique, which enables intraoperative functional assessment[12,13].

Clinical studies over the last decade have reported encouraging outcomes with IMHS fixation, including high union rates, rapid time to union, excellent total active motion (TAM) recovery, and low rates of infection and nonunion[14]. A recent large systematic review and meta-analysis comparing IMHS, K-wires, and plating for metacarpal fractures found that intramedullary fixation was associated with significantly lower disabilities of the arm, shoulder and hand (DASH) scores, higher grip strength recovery, and lower reoperation rates compared with both alternative techniques[7,15]. These findings have led many hand surgeons to adopt IMHS as the preferred option for selected extra-articular metacarpal fractures, particularly in active patients who benefit from early unrestricted mobilization.

Despite these advantages, IMHS fixation is not without controversies. Concerns persist regarding articular cartilage injury at the screw entry point, especially during retrograde insertion through the metacarpal head or antegrade insertion across the metacarpophalangeal (MCP) joint for proximal phalanx fractures[16,17]. The risk of partial extensor tendon injury during percutaneous drilling has been demonstrated in cadaveric studies[16]. Furthermore, intramedullary screws provide less inherent rotational control than open plating, making meticulous technique essential to avoid malrotation[18]. Technical errors in guidewire placement, screw diameter selection, or fracture compression management may result in cortical breach, shortening, screw prominence, or malunion[17].

The learning curve associated with percutaneous intramedullary techniques represents an additional consideration. Accurate three-dimensional understanding of the medullary canal trajectory, fluoroscopic proficiency, and familiarity with different screw designs are all required for consistent success[17]. Early in the adoption phase, surgeons may encounter longer operative times, greater fluoroscopy exposure, or higher technical complication rates until proficiency is established[19]. In addition, implant cost and availability can influence practice patterns; headless compression screws are generally more expensive than K-wires and may not be readily accessible in all healthcare systems, particularly in resource-limited environments[20,21].

The prospective observational study by from a North African trauma center adds valuable regional data to this evolving evidence base. In their series of 67 extra-articular metacarpal and proximal phalanx fractures treated with IMHS, the authors reported a 100% union rate at a mean of 5.6 weeks, favorable functional recovery with mean TAM of 253°, and a relatively low overall complication rate of 7.5%. Their protocol emphasized minimally invasive technique, widespread use of WALANT (70.2%), and early mobilization without routine splinting. These findings highlight the potential of IMHS fixation to deliver excellent outcomes in carefully selected cases managed with meticulous technique and structured rehabilitation.

Given the expanding yet still incomplete evidence base, there is a clear need to synthesize current knowledge and clarify the clinical role of IMHS fixation for metacarpal and proximal phalanx fractures. This Opinion Review aims to provide an overview of biomechanical and technical principles, discuss indications and contraindications, outline practical surgical technique considerations, and compare IMHS outcomes with K-wires and plating. We further address complications, rehabilitation strategies, and cost implications, and conclude with our perspectives on optimal case selection, technical refinements, and priorities for future research.

BIOMECHANICAL AND TECHNICAL PRINCIPLES

Biomechanical cadaveric studies have directly compared IMHS constructs with dorsal plating and lag screws for metacarpal shaft fractures, demonstrating that IMHS fixation achieves comparable or superior load-to-failure and stiffness characteristics in transverse and short oblique patterns[10,23]. A biomechanical comparison of plate vs intramedullary screw fixation found that intramedullary constructs provide favorable resistance to both axial loading and torsion in metacarpal neck and shaft fractures, supporting their use in active patients with high functional demands[10,24].

Screw design significantly influences biomechanical performance. Fully threaded headless screws (e.g., Acutrak series) distribute compressive force along the entire thread length, providing stable fixation in comminuted or transverse patterns where differential compression is undesirable[17]. Variable-pitch (partially threaded) headless screws (e.g., Herbert-Whipple design) generate interfragmentary compression through differential thread pitch, which is advantageous in simple oblique fractures with good cortical contact. The appropriate screw diameter must balance canal fill for rotational stability against the risk of endosteal pressure necrosis or articular penetration; a diameter of approximately 60%-70% of the medullary canal width is generally recommended[17].

The percutaneous medullary approach inherently preserves the periosteum, the dorsal soft-tissue envelope, and extensor tendon gliding surfaces, minimizing the biological and mechanical disruption associated with open plating[10]. This tissue preservation likely contributes to the consistently low rates of postoperative stiffness, infection, and tendon-related complications reported across IMHS series[7].

INDICATIONS, CONTRAINDICATIONS, AND PATIENT SELECTION

Indications

The ideal candidate for IMHS fixation is a skeletally mature patient with an unstable extra-articular metacarpal or proximal phalanx fracture that cannot be managed conservatively because of unacceptable displacement, shortening, or rotational malalignment. The strongest indications include: (1) Extra-articular diaphyseal or neck fractures of the second through fifth metacarpals with transverse, short oblique, or comminuted patterns; (2) Extra-articular proximal phalanx shaft fractures, particularly diaphyseal transverse or short oblique patterns; (3) Fractures in active, working-age patients where early return to function is a priority; (4) Cases suitable for WALANT technique where intraoperative functional assessment adds value[12,13]; and (5) Settings where soft-tissue preservation and avoidance of dorsal scar or hardware prominence are particularly important[25] (Table 1).

Table 1 Indications, contraindications, and key selection criteria for intramedullary headless screw vs Kirschner wire vs plate fixation in metacarpal and proximal phalanx fractures.

Criterion	IMHS	K-wire	Plating
Extra-articular transverse/oblique	Preferred	Acceptable	Acceptable
Metacarpal neck	Preferred	Acceptable	Less ideal
Comminuted diaphyseal	Acceptable	Poor control	Preferred
Intra-articular	Contraindicated	Limited role	Preferred
Osteoporotic bone	Caution	Acceptable	Preferred
Open fracture Gustilo I	Acceptable	Acceptable	Acceptable
Open fracture Gustilo II/III	Contraindicated	Caution	Preferred
Pediatric (open physes)	Contraindicated	Preferred	Rarely
Need for early motion	Best	Poor	Good
Resource-limited setting	Costly	Best	Moderate cost
Learning curve	Moderate	Low	Moderate-high

IMHS: Intramedullary headless screw; K-wire: Kirschner wire.

Contraindications

Absolute and relative contraindications must be carefully assessed before selecting IMHS as the fixation strategy: (1) Intra-articular fractures requiring open anatomical reduction and direct visualization; (2) High-grade open fractures (Gustilo type II/III) with significant contamination; (3) Fractures associated with tendon or neurovascular injury requiring formal open repair; (4) Pathological fractures or severe osteoporosis where medullary purchase is inadequate; (5) Highly comminuted or segmental fractures where rotational control cannot be assured; and (6) Pediatric patients with open physes.

Patient selection considerations

Interpretation of published outcomes requires careful contextualization within study inclusion criteria. Most high-quality IMHS series include skeletally mature patients (mean age 30-38 years) with good bone quality and predominantly diaphyseal transverse or comminuted patterns-characteristics typically associated with favorable healing potential[22,26]. Extrapolation to elderly patients with osteoporotic bone, complex intra-articular injuries, or significantly contaminated fractures should therefore be approached cautiously[27]. Patient compliance with early mobilization protocols and the ability to attend follow-up appointments are also important prerequisites, as the absence of routine splinting places greater responsibility on patient-driven rehabilitation[14,21].

SURGICAL TECHNIQUES AND TECHNICAL PEARLS

Metacarpal fractures

Retrograde single-screw fixation (standard technique): The MCP joint is flexed to 90° to bring the dorsal metacarpal head into a more accessible position. A 3 mm longitudinal skin incision is made over the MCP joint. A guidewire is inserted at the dorsal aspect of the metacarpal head and directed centrally along the intramedullary axis under fluoroscopic control in both anteroposterior and lateral planes[28,29]. Eccentric positioning predisposes to cortical breach, rotational malalignment, and screw cutout[30]. Using a blunt K-wire to initiate the entry point is recommended by some authors to reduce the risk of cortical penetration[31]. The screw thread must advance completely beyond the fracture site to ensure adequate fixation; reaching the metacarpal isthmus provides the most rigid construct. A 3.0 mm headless cannulated compression screw is standard for most metacarpals[28] (Table 2 and Figure 1).

Figure 1 Schematic overview of intramedullary headless screw fixation approaches[33]. A: Intramedullary screw fixation of a transverse metacarpal fracture; B: Y-strutting technique with two screws for a multi-fragmentary subcapital metacarpal fracture; C: Anterograde intra-articular intramedullary headless compression screw (IMCS) fixation of the proximal phalanx; D: Trans-articular technique (through the metacarpal head) for IMCS fixation of the proximal phalanx; E: Dual anterograde proximal phalanx fixation, also known as proximal phalanx’ Y-strutting; F: Retrograde IMCS fixation of the proximal phalanx. Citation: Guidi M, Frueh FS, Besmens I, Calcagni M. Intramedullary compression screw fixation of metacarpal and phalangeal fractures. EFORT Open Rev 2020; 5: 624-629. Copyright © The Author(s) 2020. Published by Bioscientifica Ltd on behalf of EFFORT. The article is open access.

Table 2 Technique selection guide for intramedullary headless screw fixation by bone and fracture pattern.

Bone	Fracture pattern	Preferred technique	Key risk
Metacarpal	Transverse shaft, subcapital, short oblique	Technique 1 retrograde single-screw	Articular cartilage at metacarpal head (4%-5% surface)
Metacarpal	Comminuted subcapital/distal shaft	Technique 2 Y-strutting double-screw	Screw conflict; must use unequal lengths
Proximal phalanx	Extra-articular shaft/neck	Technique 3 antegrade intra-articular (preferred)	Inadequate subluxation if MCP at 90°
Proximal phalanx	Subluxation inadequate	Technique 4 antegrade trans-articular	Dual articular violation (metacarpal head + phalanx base)
Proximal phalanx	Alternative retrograde access	Technique 5 PIP retrograde	Central slip injury; larger PIP chondral defect
Proximal phalanx	Comminuted proximal third	Technique 6 dual antegrade Y-strutting	Screw conflict; 2.2 mm screws mandatory

MCP: Metacarpophalangeal joint; PIP: Proximal interphalangeal joint.

Y-strutting double-screw technique (for comminuted subcapital/distal shaft fractures): In comminuted subcapital or distal shaft fractures, a single intramedullary screw risks progressive metacarpal shortening due to structural collapse of the comminuted zone. Del Piñal et al[31] proposed the Y-strutting technique, in which two guidewires are inserted in converging directions through the metacarpal head entry point. Two screws of different lengths (typically 3.0 mm and 2.2 mm) are then placed to create a triangular frame that supports the bone fragments and prevents collapse. The surgeon must anticipate and avoid mechanical conflict between the two screws; the shorter screw should not penetrate as deeply as the longer one. This construct adds rotational and axial stability beyond what a single screw can provide in multifragmentary patterns.

Proximal phalanx fractures

Four distinct techniques exist for proximal phalanx fixation with IMHS, each with specific indications, advantages, and limitations.

Antegrade intra-articular technique (preferred technique): A 3 mm incision is made over the MCP joint, which is flexed to 70° of flexion (not 90°, as the dorsal capsule and collateral ligaments at full 90° prevent dorsal subluxation of the phalanx). The surgeon applies a gentle dorsally directed subluxation force on the proximal phalanx base to expose the entry point more clearly. The guidewire is inserted at the dorsal base of the proximal phalanx and advanced along the longitudinal phalangeal axis under fluoroscopic control[32]. A 3.0 mm or 2.2 mm headless compression screw is then inserted depending on canal diameter; if the canal measures less than 3.0 mm, a 2.2 mm screw is selected. This technique produces less cartilage damage than the trans-articular approach, as only the proximal phalanx base articular surface is violated, not the metacarpal head[33].

If dorsal subluxation is insufficient, the guidewire may alternatively be advanced in an oblique direction without requiring articular violation, which further reduces chondral damage risk.

Antegrade trans-articular technique: When adequate dorsal subluxation of the proximal phalanx base cannot be achieved, or when guidewire position cannot be satisfactorily confirmed using the intra-articular approach, the trans-articular technique is employed.

Retrograde intra-articular technique (through the proximal interphalangeal joint): The proximal interphalangeal (PIP) joint is flexed to 90° and the guidewire is inserted into the proximal phalanx head and advanced retrograde. While technically simpler, this technique creates a larger area of chondral damage at the PIP joint surface and places the central slip of the extensor apparatus at significant risk.

Dual antegrade Y-strutting fixation (for comminuted proximal phalanx fractures): For comminuted extra-articular fractures of the proximal third, Gaspar et al[34] described dual antegrade IMHS using a Y-strutting construct with two 2.2 mm headless compression screws, reporting mean TAM of 258° and mean Quick DASH of 3.9 in 10 patients with no complications at mean 84 weeks follow-up.

Technical pearls

Always confirm guidewire position in two orthogonal planes before reaming[19]. Prefer screw diameter of approximately 60%-70% of medullary canal width to balance canal fill with articular safety[17]. For fully threaded screws in comminuted fractures, compress the fracture before final screw seating. Assess rotational alignment by active tenodesis and finger cascade prior to wound closure, particularly when using WALANT[12,13]. Consider a retrograde approach for metacarpals and be cautious with the antegrade phalanx approach in patients with thin or fragile extensor tendons[30,35,36]. Use intraoperative fluoroscopy liberally to confirm screw countersink below articular surface[37,38].

POSTOPERATIVE PROTOCOL AND EARLY MOBILIZATION

The postoperative rehabilitation protocol should be tailored to fracture stability, patient compliance, occupation, and pain tolerance[39]. For stable IMHS constructs in transverse or minimally comminuted fractures in compliant patients, immediate active motion with buddy taping is appropriate. For constructs with marginal stability-such as comminuted fractures near the fracture length limit of the screw or cases where fluoroscopic appearance suggests suboptimal fixation-a brief period of protective splinting (7-10 days) before initiating motion may be prudent[40,41]. Grip strengthening is typically introduced after radiographic evidence of early callus formation at 3-4 weeks[15,41].

Formal hand therapy input is beneficial in the early postoperative period to ensure correct exercise technique, monitor for stiffness, and escalate to scar management or dynamic splinting if range of motion plateaus[42]. The absence of prominent dorsal hardware after IMHS fixation facilitates scar-free recovery and reduces the incidence of extensor tendon irritation requiring physiotherapy intervention[7].

COMPARATIVE OUTCOMES VS K-WIRES AND PLATING

Multiple systematic reviews and meta-analyses over the past five years have compared IMHS fixation with K-wire and plate fixation for metacarpal and proximal phalanx fractures, consistently supporting the advantage of intramedullary techniques in appropriately selected patients[7,23,43].

The most comprehensive meta-analysis-published in 2025 by DelPrete et al[7] included 30 studies and directly compared functional and safety outcomes across the three fixation modalities for metacarpal fractures. Patients treated with intramedullary fixation had significantly lower DASH scores [0.6; 95% confidence interval (CI): 0.2-1.0] compared with K-wires (7.4; 95%CI: 4.8-9.9) and plating (9.8; 95%CI: 5.3-14.3)[7,14,44]. Intramedullary fixation also had significantly lower reoperation rates (4%) vs K-wires (11%) and plating (11%)[7]. Grip strength recovery was superior in the IMHS group compared with K-wires, though comparable to plating[7,24].

A systematic review of 837 patients undergoing IMHS fixation across 14 studies confirmed high union rates (> 97%), low infection rates (< 3%), and low nonunion rates (< 2%), outcomes comparable or superior to those reported in K-wire and plate series[14]. A separate meta-analysis specifically examining proximal phalanx fractures found that intramedullary screws were associated with superior range of motion and lower complication rates compared with K-wires, though the evidence base for phalangeal fixation remains less robust than for metacarpal injuries[32].

Comparative studies between miniplate fixation and K-wires for metacarpal shaft fractures demonstrate that plating provides rapid early functional recovery but with higher risk of extensor tendon irritation, adhesion, and hardware-related complications requiring reoperation[38,43,45,46]. K-wire fixation, while effective and inexpensive, is consistently associated with higher pin-tract infection rates, more frequent secondary procedures for wire removal, and greater postoperative immobilization requirements than either IMHS or plating[38,39].

The available comparative evidence therefore suggests that IMHS occupies a favorable clinical niche: It provides functional outcomes and complication rates superior to K-wires and broadly comparable to plating, while avoiding the soft-tissue morbidity associated with open plating. However, the majority of comparative studies are retrospective or non-randomized, and direct head-to-head randomized controlled trial (RCT) evidence remains scarce, particularly for proximal phalanx fractures[10] (Table 3).

Table 3 Comparative outcomes of intramedullary headless screw vs Kirschner wire vs plate fixation for metacarpal fractures (based on meta-analyses).

Outcome measure	IMHS	K-wire	Plating	Evidence level
DASH score (mean)	0.6	7.4	9.8	Meta-analysis[7,14]
Grip strength recovery	Superior	Moderate	Comparable to IMHS	Meta-analysis[7,24]
Reoperation rate	4%	11%	11%	Meta-analysis[7]
Infection rate	< 3%	5%-15% (pin tract)	< 3%	Systematic review[14]
Union rate	> 97%	95%-98%	> 97%	Systematic review[14]
Operative time	Short	Shortest	Longest	Cohort studies[19,21]
Early mobilization	Yes (no splint)	No (splint required)	Yes	Cohort studies[43,45]
Implant removal	Rarely required	Usually required	Sometimes required	Systematic review[38,39]
Implant cost	Moderate-high	Low	Moderate-high	Cost analysis[20]

DASH: Disabilities of the arm, shoulder and hand; IMHS: Intramedullary headless screw; K-wire: Kirschner wire.

COST AND RESOURCE CONSIDERATIONS

The economic implications of IMHS fixation must be weighed against its clinical advantages, particularly in resource-constrained healthcare systems where implant cost is a primary determinant of surgical decision-making[20,47]. Headless compression screws carry a higher per-implant cost compared with K-wires, which are available at minimal cost in most settings[20].

However, a cost comparison study published in 2025 found that the total episode cost of intramedullary screw fixation for metacarpal fractures-incorporating operative time, anesthesia, rehabilitation, and reoperation-was comparable to or lower than open reduction and internal fixation with plate and screws, largely because of shorter operative times, reduced implant and tray costs per case, and significantly lower reoperation rates[21]. The lower reoperation rate with IMHS compared with both K-wires and plating (4% vs 11%) directly reduces the downstream cost burden of secondary surgical procedures[20,21,48,49].

Additional economic advantages include the compatibility of IMHS fixation with WALANT technique, which eliminates the need for general or regional anesthesia and tourniquet equipment, potentially enabling treatment in minor operating theater settings with lower facility costs[12,47]. Earlier return to work and daily activities after unrestricted postoperative mobilization also reduces indirect socioeconomic costs in working-age patients[21].

In settings where headless compression screw implants are unavailable or cost-prohibitive, K-wire fixation remains an appropriate and effective option for many extra-articular fracture patterns. The decision to adopt IMHS should be informed by a structured assessment of local implant access, institutional expertise, and the healthcare cost model in which the surgeon practices[20].

AUTHORS’ PERSPECTIVES AND FUTURE RESEARCH DIRECTIONS

In our clinical experience, IMHS fixation represents a valuable and increasingly preferred technique for selected extra-articular metacarpal and proximal phalanx fractures, particularly in active patients where early return to function and minimization of soft-tissue morbidity are priorities. The technique’s ability to deliver stable fixation through a percutaneous approach-compatible with WALANT and immediate postoperative mobilization-aligns well with contemporary goals of hand surgery.

From a patient selection standpoint, we advocate for IMHS primarily in extra-articular diaphyseal and neck fractures that are closed or minimally open (Gustilo I), in skeletally mature patients with good bone quality and reliable compliance[25,42]. We remain cautious about applying IMHS to highly comminuted fractures with significant size mismatch between the medullary canal and available screw diameter, where rotational control may be insufficient[50,51]. In proximal phalanx fractures, we favor careful soft-tissue protection during antegrade MCP entry, and prefer to reserve this approach for patients with good compliance and the ability to attend structured rehabilitation[35,36].

Despite these advantages, several important knowledge gaps limit our confidence in recommending IMHS universally across all hand fracture subtypes. First, robust long-term outcome data beyond 24 months are scarce, and the risk of late post-traumatic articular degeneration from the entry-point cartilage defect remains incompletely quantified. Second, the existing comparative literature is dominated by retrospective single-center series; high-quality RCT data are largely absent, particularly for proximal phalanx fractures. Third, the formal learning curve for IMHS has not been well characterized in prospective studies, and training pathways for adoption are not standardized across institutions.

CONCLUSION

IMHS fixation offers a reliable, minimally invasive fixation strategy for selected extra-articular metacarpal and proximal phalanx fractures, combining mechanical stability with soft-tissue preservation and enabling early unrestricted mobilization. Current evidence from systematic reviews and meta-analyses demonstrates high union rates, low complication profiles, and functional outcomes comparable or superior to K-wire and plate fixation in appropriately selected patients.