Mini-Anchor Fixation vs Conservative Treatment for Hauck Type II Ulnar Styloid Fractures Associated With Distal Radius Fractures: A Retrospective Cohort Study

Abstract

Background

Hauck type II ulnar styloid fractures (USFs) occur at the base of the ulnar styloid process, where the triangular fibrocartilage complex attaches. Nonunion or disruption at this level may compromise distal radioulnar joint (DRUJ) stability, although the clinical significance of associated USFs in distal radius fractures (DRFs) remains debated. This retrospective cohort study compared outcomes after mini-anchor fixation vs no ulnar styloid fixation in patients with DRFs and concomitant Hauck type II USFs.

Material/Methods

Forty-five patients treated between 2021 and 2023 were included. Twenty-three patients underwent mini-anchor fixation of the ulnar styloid (group A), and 22 did not (group C). Primary outcomes were USF union and ulnar-sided or DRUJ stability-related complications. Secondary outcomes included wrist range of motion, grip strength, the Modified Mayo Wrist Score, and the Quick Disabilities of the Arm, Shoulder, and Hand score.

Results

All DRFs healed in both groups. USF union occurred in all patients in group A, whereas 2 nonunions occurred in group C (P = 0.233). Ulnar-sided pain was less frequent in group A than in group C (P = 0.346), and DRUJ subluxation occurred only in group C (P = 0.489). Range of motion, grip strength, and functional outcome scores were comparable between groups.

Conclusions

Mini-anchor fixation was associated with higher union rates and fewer ulnar-sided or DRUJ-related complications, although differences were not statistically significant, and overall wrist function was similar between groups. Given the modest sample size, these findings should be considered preliminary and require confirmation in larger prospective studies.

Level of evidence: III

Introduction

Hauck type II ulnar styloid fractures (USFs), which involve the bony prominence at the distal end of the ulna, are frequently encountered alongside distal radius fractures (DRFs), with reported incidences varying from 22% to 65% across published series [1–3]. The distal radioulnar joint (DRUJ), formed by the articulation between the distal radius and ulna, is central to forearm pronation and supination. The triangular fibrocartilage complex (TFCC), a fibrocartilaginous ligamentous structure that stabilizes the DRUJ, inserts near the base of the ulnar styloid. Fractures at the ulnar styloid base can therefore disrupt the osseoligamentous anchorage of the TFCC, potentially undermining DRUJ stability and ulnar-sided wrist function [4–6]. A Hauck type II fracture, in this context, denotes a fracture through the ulnar styloid base. When nonunion develops at this level, it may similarly impair TFCC-mediated stabilization and give rise to persistent DRUJ instability. The clinical significance of concomitant USFs in patients with DRFs, accordingly, remains an important yet unresolved question.

Several classification systems have been proposed to categorize USFs according to their anatomical location and biomechanical relevance [7–9]. The Palmer and Hauck systems differentiate tip fractures from base fractures on the basis of fracture level and the anticipated risk to DRUJ stability. Under these frameworks, tip fractures are generally regarded as more benign, while base fractures classified as Hauck type II involve the region of TFCC attachment and carry a theoretical predisposition to DRUJ instability. Previous studies have similarly highlighted the clinical relevance of USFs occurring alongside DRFs, particularly when the fracture line traverses the styloid base [10,11].

Despite this anatomical reasoning, clinical studies examining USFs in the context of DRFs have yielded discordant conclusions. Some authors have reported that unrepaired base fractures may impair DRUJ stability and worsen outcomes following distal radius fixation, while others have observed no appreciable difference in wrist function or radiographic alignment, irrespective of ulnar styloid management [12,13]. These discrepancies likely stem, at least in part, from heterogeneity in fracture subtypes studied, methods of DRUJ assessment, indications for treatment, and outcome metrics employed.

From a treatment perspective, conservative management and surgical fixation have been advocated for USFs [12–14]. In the present study, Hauck type II morphology was considered an anatomical risk factor for potential TFCC-related DRUJ instability rather than an automatic surgical indication [15,16]. Fixation of the ulnar styloid was undertaken when a base fracture coexisted with persistent or gross DRUJ instability, substantial fragment displacement, clinically symptomatic instability, or failure to restore DRUJ congruity after stabilization of the distal radius [17,18].Traditional fixation methods, including Kirschner wires, tension-band constructs, and screws, can provide mechanical stability but are frequently associated with hardware-related complications, such as soft-tissue irritation, migration, and the need for secondary removal, owing to the subcutaneous location of the ulnar styloid [13,19]. Mini-anchor fixation represents a suture-anchor approach in which a small anchor is placed into the ulnar styloid base and sutures are passed to secure the fracture fragment while retensioning the attached TFCC-related soft tissues [20]. Although this technique may stabilize the fragment with less implant prominence, comparative clinical data specifically addressing mini-anchor fixation for Hauck type II USFs remain scarce.

Most prior investigations have concentrated on global wrist function after DRF fixation, an outcome largely governed by the characteristics and management of the radius fracture itself [15]. As a consequence, differences in ulnar styloid healing and ulnar-sided or DRUJ-related complications attributable specifically to the styloid injury may have gone underappreciated. Although earlier work has suggested that fixation can promote union of ulnar styloid base fractures and facilitate restoration of DRUJ stability [18], direct comparative evidence for patients with Hauck type II USFs treated in the setting of surgically stabilized DRFs remains limited. Therefore, the purpose of this retrospective single-center study, including 45 patients with Hauck type II USFs associated with DRFs, was to compare outcomes between those treated with and without mini-anchor fixation of the ulnar styloid.

Given the retrospective, nonrandomized design, the study was conceived as an exploratory association-level comparison. Our hypothesis was that mini-anchor fixation would be associated with a higher ulnar styloid union rate and fewer ulnar-sided or DRUJ-related complications, while overall wrist function would be driven primarily by the DRF itself rather than by the approach to ulnar styloid management.

Material and Methods

Study Design and Ethics Statement

This study was designed as a single-center retrospective cohort study and was intended as an exploratory comparative association analysis rather than a definitive treatment-effect study. Adult patients who underwent surgical fixation of a distal radius fracture accompanied by Hauck type II USFs (Figure 1) between January 2021 and October 2023 were screened for eligibility. This study was approved by the Ethics Committee of Wuhan Fourth Hospital on March 31, 2025 (approval No. KY2025-083-01). The requirement for informed consent was waived by the Ethics Committee because of the retrospective nature of the study. The study was conducted in accordance with the Declaration of Helsinki. Demographic data and injury profiles of both groups are summarized in Table 1.

Figure 1.

Preoperative computed tomography with 3-dimensional reconstruction demonstrating a distal radius fracture associated with a Hauck type II ulnar styloid fracture.

Table 1.

Baseline demographic and injury characteristics of the mini-anchor group (A) and conservative treatment group (C).

Characteristics	Group A (n = 23)	Group C (n = 22)	P value*
Age, years	54.57 ± 12.53	59.41 ± 10.46	0.166
Sex (male/female)	7/16	7/15	0.920
Injured side (right/left)	13/10	10/12	0.556
Dominant side injury	13 (57%)	10 (45%)	0.556
Time to surgery (days)	3.13 ± 0.81	3.68 ± 1.52	0.143

Group A consisted of patients treated with mini-anchor fixation of the Hauck Type II Ulnar Styloid Fractures, and group C consisted of patients managed without ulnar styloid fixation.

^*P values in bold represent statistical significance (P < 0.05).

Inclusion and Exclusion Criteria

The inclusion criteria were age 18 years and older, closed distal radius fracture treated with volar locking plate fixation, concomitant Hauck type II USFs, and a minimum postoperative follow-up of 13 months. The exclusion criteria included open or pathologic fractures, bilateral wrist injuries, prior wrist surgery, inflammatory or degenerative wrist disease, associated carpal fractures, and incomplete radiographic or clinical follow-up. The adult inclusion criterion was used to reflect the clinical population treated for DRFs. No upper age limit was applied; elderly patients were therefore eligible if they met the radiographic and clinical criteria and had no clinically significant inflammatory or degenerative wrist disease requiring exclusion.

Treatment Allocation

Patients were classified into 2 groups based solely on whether mini-anchor fixation of the Hauck type II USFs was performed at the time of distal radius fixation. Group A included patients who underwent mini-anchor fixation, and group C included patients managed without ulnar styloid fixation. Treatment allocation reflected surgeon practice and patient preference during the study period rather than a randomized protocol. Consequently, selection bias and unmeasured confounding may have influenced the observed associations, and causal interpretation of comparative treatment benefit is limited. During the study period, the decision not to fix the ulnar styloid in group C reflected real-world individualized management after distal radius reduction and intraoperative DRUJ assessment, rather than omission of an indicated procedure in patients with definite gross DRUJ instability. Hauck type II morphology alone was therefore not used as an absolute surgical indication in the absence of confirmed instability.

Radiographic and Clinical Assessment

All available preoperative, immediate postoperative, and follow-up wrist radiographs were re-reviewed in standardized posteroanterior and lateral views. Because preoperative magnetic resonance imaging (MRI) or wrist arthroscopy was not routinely performed in this retrospective cohort, definite TFCC or DRUJ ligament tears were not classified as separate structural diagnoses; instead, DRUJ involvement was evaluated using combined intraoperative, clinical, and radiographic criteria.

Standard posteroanterior and lateral wrist radiographs were obtained on postoperative day 1 and at 3, 6, and 12 months. DRUJ instability was diagnosed when at least 2 of 3 clinical findings (ulnar-sided pain with rotation or loading, piano-key test, and DRUJ ballottement test) were present together with radiographic malalignment, defined as dorsal or volar translation of the ulnar head greater than 50% of its width on the lateral view or asymmetry of the DRUJ space on the posteroanterior view. Radiographic assessment specifically included DRUJ congruity, ulnar head translation, DRUJ space symmetry, distal radius union, ulnar styloid union or nonunion, and postoperative subluxation. USF healing was assessed on serial posteroanterior and lateral radiographs by 2 blinded observers, and nonunion was defined as persistence of a visible fracture line without bridging at 6 months or later. Range of motion (ROM), grip strength, the Modified Mayo Wrist Score, and the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score were recorded at final follow-up.

For the purposes of this retrospective analysis, a DRUJ ligament tear was considered definitively present only if supported by MRI, wrist arthroscopy, or direct intraoperative visualization. No patients had such definitive documentation. Cases showing postoperative DRUJ symptoms or malalignment were therefore reported as DRUJ instability or subluxation rather than as confirmed DRUJ ligament tears.

Accordingly, group C consisted of patients with Hauck type II USFs who underwent distal radius fixation but did not receive direct ulnar styloid fixation, because frank DRUJ instability requiring additional stabilization was not documented at the index operation. If definite unstable DRUJ disruption had been identified, additional measures such as ulnar styloid fixation, long-arm immobilization, or temporary radioulnar pinning would have been considered according to standard treatment principles.

Surgical Procedure

All procedures were performed by the same surgical team using a standardized institutional protocol. Distal radius fractures were treated through a volar approach with locking plate fixation to achieve stable anatomic reduction. Under brachial plexus block anesthesia, the Henry approach was used. An L-shaped incision was made, and the pronator quadratus was elevated to expose the fracture site. After thorough debridement of the fracture surfaces, traction and reduction were performed under direct visualization using reduction clamps to restore radial height, palmar tilt, articular congruity, and ulnar variance. Temporary fixation was achieved with Kirschner wires, followed by definitive volar plate fixation. At least 3 locking screws were placed in both the proximal and distal segments across the fracture zone. Final reduction was confirmed fluoroscopically before layered wound closure.

In group C, the USF was left untreated. In group A, ulnar styloid fixation was performed using a mini-anchor system (Beijing Tianxing Co) through a standardized ulnar approach (Figures 2–4). With the elbow flexed to 90° and the forearm in neutral rotation, a 3-cm longitudinal incision was made along the ulnocarpal axis over the ulnar head. Dissection was carried through the interval between the extensor and flexor carpi ulnaris, with care taken to protect the dorsal branch of the ulnar nerve. The periosteum was incised to expose the fracture fragments while preserving the ulnar collateral ligament and the TFCC insertion. After removal of hematoma and interposed tissue, a 1.8-mm mini-anchor was inserted into the center of the ulnar styloid base under fluoroscopic guidance to ensure appropriate depth and orientation. Anchor stability was confirmed by tensioning the suture.

Figure 2.

Photograph of the mini-anchor system used for ulnar styloid fixation.

Figure 3.

Schematic illustration of mini-anchor fixation for a Hauck type II ulnar styloid base fracture.

Figure 4.

Intraoperative views of mini-anchor fixation: (A) exposure of the ulnar styloid base fracture; (B) insertion of the mini-anchor; and (C) passage and tying of the sutures through the bone tunnel to secure the fragment. The sutures were tied using a 2-knot configuration to distribute tension and enhance rotational stability of the ulnar styloid base fragment. The figure demonstrates an open ulnar approach, which provides direct visualization and controlled anchor placement rather than a percutaneous technique.

This ulnar approach was used as an open technique with direct visualization, rather than as a percutaneous procedure. The incision was admittedly larger than what would be required for closed reduction percutaneous pinning or percutaneous cannulated screw fixation; however, the trade-off was justified by several practical advantages. Direct exposure of the ulnar styloid base enabled the surgeon to identify and protect the dorsal sensory branch of the ulnar nerve, clear any hematoma or interposed soft tissue from the fracture site, and achieve anatomical reduction of the base fragment under visual confirmation. Additionally, this exposure facilitated precise positioning of the mini-anchor at the TFCC attachment region, which would be difficult to verify through a limited percutaneous window.

A 1.5-mm Kirschner wire was then used to create a transosseous tunnel approximately 1.0 to 1.5 cm distal to the ulnar styloid along the ulnar shaft. Using a suture passer, the anchor sutures were passed through the tunnel and retrieved proximally. After reduction of the ulnar styloid fragment, the sutures were looped around the ulnar neck and tied with appropriate tension to secure anatomic reduction without overcompression. In group A, wrist flexion, extension, pronation, and supination were assessed intraoperatively to confirm fracture stability and DRUJ congruity. Final reduction was verified fluoroscopically, and the incision was closed in layers (Figure 5).

Figure 5.

Representative postoperative radiograph demonstrating anatomic reduction of the ulnar styloid base fracture and assessment of distal radioulnar joint congruity.

Postoperative Management and Rehabilitation

No drains were used, and no postoperative immobilization with casts or splints was applied. Prophylactic cefuroxime sodium (1.5 g every 8 hours) was administered for 48 hours postoperatively. The operated limb was elevated to reduce swelling, and active ROM exercises of the shoulder, elbow, and fingers were initiated on postoperative day 1. Wrist flexion, extension, and forearm rotation exercises were begun 2 weeks after surgery, as tolerated. Early mobilization was initiated only once acceptable distal radius fixation and DRUJ congruity had been confirmed intraoperatively. Routine long-arm splinting or casting was not deemed necessary in these cases, as none demonstrated definite unstable DRUJ ligament tear or gross DRUJ instability on examination. Had persistent DRUJ instability been identified, the protocol would have called for long-arm immobilization or temporary radioulnar pinning instead.

Statistical Analysis

All analyses were performed using SPSS software version 24.0 (IBM Corp, Armonk, NY, USA). The Shapiro-Wilk test was applied to assess the normality of the distribution. Continuous variables are presented as mean ± standard deviation, while categorical variables are shown as frequencies and percentages. The t test and Fisher exact test were used for comparisons between 2 groups. A P value < 0.05 was considered statistically significant. Fisher’s exact test was used for categorical outcomes with very low event counts, such as ulnar styloid nonunion. Given the small numbers involved, these results were interpreted descriptively rather than as definitive tests of significance, since statistical power was inherently limited.

Results

Forty-five patients with distal radius fractures associated with Hauck type II USFs were included. The mean age was 56.9 ± 11.6 years (range, 20–75 years), and 28.9% of patients were men. The mean follow-up was 15.5 months (range, 13–27 months). Injuries involved the dominant wrist in 51.1% of cases. Baseline demographic and injury characteristics were comparable between the mini-anchor group (group A) and the conservative group (group C), with no significant between-group differences (Table 1). The cohort thus encompassed a broad age range, from younger adult to geriatric patients. Age distribution was comparable between the 2 groups, which reduces, although does not eliminate, the possibility of age-related confounding.

Review of the available records and posteroanterior and lateral radiographs did not identify any separately documented preoperative frank DRUJ dislocation. Definite TFCC or DRUJ ligament tears were not coded as independent baseline variables, for the simple reason that they had not been systematically confirmed by MRI or arthroscopy in this cohort. As a result, none of the 45 included patients carried a classification of definitively confirmed stable or unstable DRUJ ligament tear. All patients did have Hauck type II ulnar styloid base fractures, but in no case was there a documented unstable DRUJ tear of the kind that would have mandated long-arm casting or temporary radioulnar pinning at the time of surgery.

At final follow-up, no significant differences were observed between groups in functional outcomes (Table 2). The mean Modified Mayo Wrist Score was 84.76 in group A and 83.69 in group C, and the mean QuickDASH score was 10.27 and 7.50, respectively. Mean grip strength was 34.13 kg in group A and 33.87 kg in group C. These findings indicate similar overall wrist function between treatment strategies.

Table 2.

Comparison of function outcomes at the final follow-up of the mini-anchor group (A) and conservative treatment group (C).

Items	Group A	Group C	P value*
MMWS	84.76 ± 6.60	83.69 ± 7.79	0.62
QuickDASH	10.27 ± 2.50	11.20 ± 3.59	0.32
Grip strength (kg)	34.13 ± 4.40	33.87 ± 6.90	0.88

Group A consisted of patients treated with mini-anchor fixation of the Hauck Type II Ulnar Styloid Fractures, and group C consisted of patients managed without ulnar styloid fixation. Abbreviations: MMWS, Modified Mayo Wrist Score; QuickDASH, Quick Disabilities of the Arm, Shoulder, and Hand.

^*P values in bold represent statistical significance (P < 0.05).

Wrist motion was comparable between groups (Table 3). In group A, mean supination, pronation, flexion, and extension were 82.54°, 79.31°, 82.70°, and 83.78°, respectively, compared with 80.94°, 77.24°, 81.03°, and 81.83° in group C. None of these parameters differed significantly between groups.

Table 3.

Comparison of wrist range of motion between the mini-anchor group (A) and conservative treatment group (C).

Items	Group A	Group C	P value*
Supination	82.54 ± 5.31	80.94 ± 6.80	0.39
Pronation	79.31 ± 5.48	77.24 ± 6.32	0.25
Flexion	82.70 ± 2.85	81.03 ± 4.12	0.12
Extension	83.78 ± 2.60	81.83 ± 4.80	0.10

Group A consisted of patients treated with mini-anchor fixation of the Hauck Type II Ulnar Styloid Fractures, and group C consisted of patients managed without ulnar styloid fixation.

^*P values in bold represent statistical significance (P < 0.05).

All distal radius fractures healed in both groups (Table 4). Radiographic union of the ulnar styloid was achieved in all patients in group A, whereas 2 nonunions occurred in group C. Ulnar-sided rotational pain was observed in 1 patient in group A and 3 patients in group C, and 1 patient in group C developed DRUJ subluxation confirmed clinically and radiographically. No neurovascular injury or surgical site infection occurred. Overall, the incidence of ulnar styloid–related complications was significantly lower in group A than in group C (P < 0.05). Functional outcomes and wrist motion were analyzed as secondary endpoints and were not intended to isolate the effect of ulnar styloid fixation from the influence of the distal radius fracture. Closed reduction percutaneous radioulnar pinning was not performed in any patient, as no case demonstrated intraoperative gross DRUJ instability that would have warranted temporary ulnoradial fixation. Regarding ulnar styloid nonunion as an isolated endpoint, only 2 events were observed in group C, and this number is too small to yield robust statistical conclusions given the overall sample size. We therefore treat this finding as an exploratory signal rather than definitive evidence of superiority.

Table 4.

Ulnar styloid union and ulnar-sided complications in the of the mini-anchor group (A) and conservative treatment group (C).

Items	Group A (n = 23)	Group C (n = 22)	P value*
Nonunion	0	2	0.233
Ulnar rotation pain	1	3	0.346
DRUJ subluxation	0	1	0.489
Total number	1 (4.35%)	6 (27.27%)	0.047*

Group A consisted of patients treated with mini-anchor fixation of the Hauck Type II Ulnar Styloid Fractures, and group C consisted of patients managed without ulnar styloid fixation. The primary endpoints were ulnar styloid fracture union and the incidence of ulnar-sided or distal radioulnar joint–related complications. Abbreviation: DRUJ, distal radioulnar joint.

^*P values in bold represent statistical significance (P < 0.05).

Discussion

The principal findings of this exploratory retrospective cohort study were that the mini-anchor fixation of Hauck type II USFs was associated with a higher ulnar styloid union rate and fewer ulnar-sided or DRUJ-related complications when compared with management without direct ulnar styloid fixation. Overall wrist function, grip strength, and ROM, however, did not differ meaningfully between the 2 groups at final follow-up. Taken together, these observations suggest that the benefit of mini-anchor fixation may be confined largely to local ulnar styloid healing and ulnar-sided or DRUJ-related symptomatology, while global wrist function appears to be governed predominantly by the DRF and the quality of its reduction and fixation.

These results warrant interpretation alongside the existing literature on USFs accompanying DRFs. May et al underscored the clinical relevance of USFs in the DRF population, especially when the fracture line involves the styloid base, given the potential implications for DRUJ stability [21]. Recent systematic reviews and meta-analyses have likewise demonstrated that operative stabilization of ulnar styloid base fractures can improve union rates, yet improved union has not consistently translated into better DASH scores, Patient-Rated Wrist Evaluation scores, wrist motion, grip strength, or final radiographic parameters [6,22]. Our data align with this pattern: mini-anchor fixation was associated with improved local fracture healing and fewer ulnar-sided or DRUJ-related complications, but no discernible advantage in overall functional outcomes emerged. This reinforces the notion that local ulnar styloid-related outcomes and global wrist function represent distinct domains and should be evaluated separately.

The anatomical and biomechanical significance of Hauck type II USFs derives from the relationship between the ulnar styloid base and the osseoligamentous attachment of the TFCC. The dorsal and volar radioulnar ligaments, as primary stabilizing components of the TFCC, are integral to maintaining DRUJ congruity throughout forearm rotation. Displacement or nonunion at the styloid base can compromise this TFCC-mediated stabilization, permit abnormal translation of the distal ulna, and contribute to DRUJ instability or ulnar-sided wrist pain [22]. Restoration of osseoligamentous continuity at this site offers a plausible mechanism for the reduced frequency of ulnar-sided and DRUJ-related complications observed in the fixation group, even though wrist motion and grip strength were not significantly different between groups.

The findings in group C merit cautious interpretation. In this study, conservative management denoted distal radius fixation without concomitant ulnar styloid fixation; it did not refer to a standardized casting-only protocol. The decision to leave the ulnar styloid unfixed reflected individualized clinical judgment following distal radius reduction and intraoperative DRUJ stability assessment. Hauck type II morphology by itself was not treated as an absolute indication for fixation in the absence of confirmed gross DRUJ instability. The 2 cases of nonunion observed in group C are clinically noteworthy and lend support to a potential union benefit of fixation, but they should not be taken as evidence that every Hauck type II fracture requires surgical stabilization or that conservative management was inappropriate across the board. Fragment size, degree of displacement, local vascularity, residual soft tissue continuity, postoperative activity level, and individual healing capacity likely also played a role in determining union outcomes.

Traditional fixation methods for USFs, including Kirschner wires, tension-band constructs, and screws, provide mechanical stability but carry risks of implant prominence, soft tissue irritation, migration, and secondary removal, given the subcutaneous position of the ulnar styloid [18,23,24]. Mini-anchor fixation operates on a different principle. A small anchor is placed into the ulnar styloid base, and sutures are passed to secure the fragment while retensioning the TFCC-related soft tissues. The advantage of this approach does not reside in a smaller incision. The open ulnar exposure permits direct visualization of the styloid base, removal of interposed tissue, controlled fracture reduction, protection of the dorsal sensory branch of the ulnar nerve, and avoidance of prominent metallic hardware. Mini-anchor fixation should therefore not be characterized as less invasive than closed reduction percutaneous radioulnar pinning or percutaneous cannulated fixation with respect to the surgical approach. Its potential value lies instead in the ability to achieve direct reduction, TFCC-related retensioning, rotational control of the base fragment, and diminished implant prominence.

The 2-knot configuration used in the present technique should be understood as a technical measure aimed at enhancing fixation security rather than as an indication that a single-knot construct is inherently inadequate. The rationale was to distribute suture tension across the ulnar styloid base and ulnar neck, improve rotational control of the small fragment, and maintain TFCC-related soft tissue tension during early wrist and forearm mobilization. In selected cases with a larger fragment and stable reduction, a single-knot configuration may be sufficient. The 2-knot approach was used uniformly in this cohort to minimize technical variability. Because a direct comparison between 1-knot and 2-knot constructs was not performed, no conclusion regarding the biomechanical superiority of either configuration can be drawn from these data.

It is also important to note that the present cohort consisted of patients with Hauck type II USFs in whom DRUJ stability was assessed clinically and radiographically, rather than a population with MRI- or arthroscopy-confirmed TFCC or DRUJ ligament tears. Had definite unstable DRUJ ligament disruption been identified following distal radius fixation, additional measures, such as long-arm immobilization, ulnar styloid fixation, or temporary radioulnar pinning, would have been undertaken. No patient in this cohort had definitive documentation of an unstable DRUJ ligament tear by MRI, wrist arthroscopy, or direct intraoperative visualization. For this reason, cases presenting with postoperative symptoms or malalignment were reported as DRUJ instability or subluxation rather than as confirmed ligament tears. This distinction matters, as it avoids the implication that patients with documented unstable DRUJ disruption were managed without appropriate stabilization.

DRFs may also give rise to soft tissue complications that extend beyond osseous union and DRUJ-related pathology. Kawamura et al recently described acute extensor pollicis longus tendon injury occurring in the setting of a DRF, underscoring the need for careful evaluation of concomitant tendon damage when fracture morphology or clinical findings raise suspicion [25]. Although tendon injury was not a primary endpoint of the present study, this broader complication spectrum highlights the importance of comprehensive clinical assessment in patients with DRFs and associated ulnar-sided injuries.

This study has several limitations that warrant consideration. First, as a single-center retrospective cohort investigation with a relatively small sample size, treatment allocation was nonrandomized and reflected surgeon preference, intraoperative assessment, and patient-related factors, meaning that selection bias and unmeasured confounding cannot be excluded. The findings should therefore be interpreted as exploratory associations rather than definitive evidence of treatment superiority. Second, the small number of outcome events, particularly ulnar styloid nonunion and DRUJ-related complications, limited statistical power for detecting meaningful between-group differences. Third, because routine MRI, wrist arthroscopy, and direct intraoperative visualization were not performed, TFCC integrity and DRUJ ligament status could not be definitively characterized; instead, DRUJ involvement was assessed on the basis of clinical examination, intraoperative stability testing, and standardized radiographs. Fourth, several variables that may influence union, pain, grip strength, and functional recovery, including DRF morphology, ulnar styloid fragment size and displacement, bone mineral density, osteoporosis severity, and mild preexisting degenerative changes, were not systematically controlled for. Fifth, this study compared mini-anchor fixation with management without direct ulnar styloid fixation and did not include head-to-head comparisons with closed reduction percutaneous radioulnar pinning, percutaneous cannulated screw fixation, Kirschner-wire fixation, tension-band wiring, or alternative knot configurations. Larger prospective studies with standardized surgical indications, advanced imaging protocols, predefined DRUJ stability criteria, and longer follow-up are needed to validate these preliminary findings and identify which patients with Hauck type II USFs are most likely to benefit from ulnar styloid fixation.

Conclusions

In this single-center nonrandomized retrospective cohort, mini-anchor fixation of ulnar styloid base fractures was associated with a higher rate of radiographic union and fewer ulnar-sided and DRUJ-related complications compared with conservative treatment in patients undergoing DRF fixation. However, global wrist function and motion were similar between groups, reflecting the dominant influence of the DRF on overall clinical outcomes. Given the small sample size, retrospective design, and potential for selection bias, these findings should be interpreted as hypothesis-generating. Larger, prospective studies are required to determine whether improved ulnar styloid healing and stability translate into durable clinical benefit. These results should therefore be viewed as supporting selective rather than routine fixation of all Hauck type II USFs. In particular, the observed nonunion difference should be regarded as hypothesis-generating because only 2 nonunion events occurred, and the treatment strategy was not randomized.

Availability of Data and Materials

The datasets used and/or analyzed during the present study, including anonymized postoperative posteroanterior and lateral wrist radiographs when permitted by institutional policy, are available from the corresponding author on reasonable request.