Validation of HAND OA US inflammatory and structural damage score (HOUSE) for thumb base joints: Systematic review on truth & discrimination.

OBJECTIVES: Recently, the HAND osteoarthritis (OA) ULTRASOUND (US) Examination (HOUSE) inflammatory and structural damage scores were developed by the OMERACT US working group. However, the thumb base was not or only partly included. This systematic review examines US scoring methods and scanning techniques assessing thumb base OA, alongside existing evidence on validity, reliability, and responsiveness. METHODS: A comprehensive search strategy in three different databases identified 30 eligible studies. RESULTS: In general, studies predominantly focused on US assessment of the carpometacarpal (CMC) 1 joint, with fewer investigating the scaphotrapeziotrapezoid (STT) joint. Most studies utilized a semiquantitative scale for scoring structural and inflammatory features, aligning with the HOUSE scoring system. Validity was supported by a limited number of studies, with one demonstrating a positive association between US structural damage and radiographic damage, and another showing a similar association with function. Associations between US inflammatory features and pain were observed, albeit with some variability. Reliability was from moderate to good for the CMC1 joint but limited for STT joint. Responsiveness varied across studies. The methodological quality of included studies varied, indicating areas for future research improvement. CONCLUSION: While promising, additional research is necessary to validate the HOUSE scoring system and improve its clinical utility for thumb base OA assessment. Future research should concentrate on optimal scanning positions and on the reliability and responsiveness of the HOUSE scoring system.

Distribution of nerve endings in human thumb interphalangeal joint.

This study aims to quantitatively analyze the distribution of encapsulated nerve endings in the human thumb interphalangeal (IP) joint capsule. There are three types of nerve endings. Type-I nerve endings (Ruffini-like ending) sense pressure changes, Type II (Pacini-like ending) nerve endings contribute to the kinesthetic sense, and Type III (Golgi-like ending) nerve ending provides proprioceptive information. We dissected five right thumbs IP joints from freshly frozen cadavers (5 men). The mean age of the cadavers at the time of death was 63.4 years (55-73). Sections were stained with the hematoxylin-eosin and antiprotein gene product 9.5 (PGP9.5) to identify encapsulated nerve endings. Transverse sections were cut and divided into volar, dorsal, and then into two equal parts, proximal and distal. The density of encapsulated nerve endings compared to volar versus dorsal and proximal versus distal regions was examined. This study showed that type 1 nerve endings were more common in the distal parts of the IP joint (p < 0.05). Also, type 3 nerve endings were observed in the thumb IP joint. There was no difference between regions in type II and type III nerve endings. The current study demonstrates that the distribution of encapsulated nerve endings in the IP joint is different from the PIP and DIP joints. Moreover, further studies are required to understand the thumb's physiology.

A case of superficial acral fibromyxoma masquerading as squamous cell carcinoma of the thumb: A case report.

A wide spectrum of tumors may affect the periungual spaces of the digits. Superficial acral fibromyxoma (SAF) is a rare, benign soft tissue tumor with diverse clinical presentations. We present a case of a 55-year-old woman with a 2-year history of a solitary periungual tumor on the left thumb, subjected to multiple episodes of trauma. Initially suspected to be a periungual squamous cell carcinoma (SCC) based on clinical and dermoscopic features, the tumor was confirmed to be a CD34- SAF through histopathology and immunohistochemistry. Although CD34 immunoreactivity is common in SAF, one-third of these tumors, including this case, do not stain for this marker. Periungual SCC considered a "great mimicker of nail tumors," may resemble other benign nail tumors such as SAF. The patient underwent complete surgical excision with primary closure, resulting in no recurrence after 1 year. This case highlights SAF as an underrecognized benign entity that may manifest with features suspicious of malignancy, potentially leading to unnecessarily aggressive interventions. Recognizing SAF through accurate biopsy techniques and thorough histopathologic evaluation, even in the absence of CD34 reactivity, is crucial for appropriate treatment and preservation of hand function and appearance.

Daytime Functional Usage Versus Night-Time Wearing: Identifying the Optimal Wearing Regimen for a Custom-Made Orthosis in the Treatment of Trapeziometacarpal Osteoarthritis.

OBJECTIVE: To compare the functional (daytime) use to the nightly use of an orthosis for patients affected by trapeziometacarpal osteoarthritis (OA). DESIGN: Randomized, controlled single-blind trial. SETTING: The rheumatology outpatient clinic of the University. PARTICIPANTS: Sixty participants diagnosed with trapeziometacarpal OA. INTERVENTIONS: Participants were randomly assigned into 2 groups: a functional group that used a functional hand-based thumb immobilization orthosis during activities of daily living and a night-time group that used the same orthosis at night. MAIN OUTCOMES MEASURES: The patients were evaluated at baseline and after 45, 90, 180, and 360 days considering: pain at the base of the thumb and in the hand, range of motion of the thumb, grip, and pinch strength, manual dexterity, and hand function. RESULTS: The groups were homogeneous at the beginning of the trial. No statistically significant difference was observed between groups over time for trapeziometacarpal pain (P=.646). For general hand pain, no statistically significant difference was found between groups over time (P=.594). Although both groups improved from baseline, there were no statistically significant differences between the groups in the vast majority of the assessed parameters. Statistically significant differences between the groups were found only in the following outcomes: thumb palmar abduction of the right hand (P=.023), pick-up test with closed eyes of the right hand (P=.048), and tripod grip strength of the right hand (P=.006). CONCLUSIONS: Both groups showed improvement in pain and function from baseline to the end of the intervention. However, there were no reported differences in these outcomes after a 1-year follow-up between the functional (daytime) and night-time use of orthosis in patients with trapeziometacarpal OA. This suggests that both types of usage can be offered to patients.

Different Thumb Positions in the Tetraplegic Hand.

OBJECTIVE: To analyze factors associated with malposition that affects function of the thumb in individuals with tetraplegia. DESIGN: Retrospective cross-sectional study. SETTING: Rehabilitation Center for Spinal Cord Injury. PARTICIPANTS: Anonymized data from 82 individuals (68 men), mean age 52.9±20.2 (SD) with acute/subacute cervical spinal cord injury C2-C8 AIS A-D recorded during 2018-2020. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Motor point (MP) mapping and manual muscle test (MRC) of 3 extrinsic thumb muscles (flexor pollicis longus (FPL), extensor pollicis longus (EPL), and abductor pollicis longus (APL)). RESULTS: 159 hands in 82 patients with tetraplegia C2-C8 AIS A-D were analyzed and assigned to "key pinch" (40.3%), "slack thumb" (26.4%), and "thumb-in-palm" (7.5%) positions. There was a significant (P<.0001) difference between the 3 thumb positions depicted in lower motor neuron (LMN) integrity tested by MP mapping and muscle strength of the 3 muscles examined. All studied muscles showed a significantly different expression of MP and the MRC values (P<.0001) between the "slack thumb" and "key pinch" position. MRC of FPL was significantly greater in the group "thumb-in-palm" compared with "key pinch" position (P<.0001). CONCLUSIONS: Malposition of the thumb due to tetraplegia seems to be related to the integrity of LMN and voluntary muscle activity of the extrinsic thumb muscles. Assessments such as MP mapping and MRC of the 3 thumb muscles enable the identification of potential risk factors for the development of thumb malposition in individuals with tetraplegia.

Paediatric trigger thumb: Diagnostic pearls.

AIM: The purpose of this study is to report diagnostic pearls and review the clinical presentation and outcomes of surgical treatment of paediatric trigger thumbs. METHODS: A retrospective review of medical records and imaging studies was performed on children with trigger thumbs from January 2009 to December 2019. RESULTS: Sixty-four trigger thumbs in 52 consecutive patients were treated. The average age at referral was 2.5 years. Symptoms include pain (4), triggering (14) and fixed contracture (38). The average symptom duration was 8 months. Forty patients had been evaluated and referred by a paediatrician or primary care doctor. Twenty-four of the 52 (46%) patients received hand x-rays and were initially misdiagnosed as a fracture or dislocation. Physical exam demonstrated a volar nodule in 64 thumbs (100%), fixed flexion deformities in 38 (73%) thumbs and triggering with active extension of the interphalangeal joint in 14 (27%) thumbs. The average age at surgery was 3.2 years. Follow-up averaged 12 months. Surgery resulted in complete relief of symptoms and correction of deformity. There was no reported loss of function or complication. CONCLUSIONS: Children with trigger thumbs who ultimately undergo surgery present with distinct physical exam findings, including a volar nodule and a fixed flexion contracture. Understanding these pearls can minimise misdiagnosis of the condition as a fracture or dislocation. Highlighting trigger thumbs during musculoskeletal education for paediatric and primary care physicians is recommended. Surgical outcomes were excellent in patients aged 2-8 years old.

Effective shape of ball-and-socket prosthesis in restoring range of thumb motion for total thumb carpometacarpal joint arthroplasty: three-dimensional motion analysis.

PURPOSE: Total joint arthroplasty (TJA) has often been used to treat thumb carpometacarpal (CMC) osteoarthritis (OA). However, guidelines for the CMC prosthesis shape remain unclear. This study aimed to identify the effective shape of a ball-and-socket prosthesis in restoring the range of thumb motion after TJA. METHODS: The participants were 10 healthy young adult men (22-32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD. RESULTS: We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values. CONCLUSION: Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis.

Mid- and long-term clinical results of the Elektra and Moovis prosthesis for trapeziometacarpal joint replacement.

BACKGROUND: Total joint arthroplasty as a surgical treatment option for trapeziometacarpal joint arthritis is recently revived. The aim of this study is to report on mid- and long-term results of the Elektra (single-mobility) and Moovis (dual-mobility) prosthesis for treatment of primary thumb carpometacarpal joint arthritis. METHODS: In this retrospective, monocentric, descriptive cohort study, 31 prostheses were evaluated that were implanted by a single surgeon in 26 patients between 2009 and 2019. Indication for surgery was trapeziometacarpal joint osteoarthritis (Eaton/Littler Stage II and III). Clinical and radiological follow-up was performed at a minimum of 24 months. The postoperative assessment included range of motion, pain, strength as well as functional scores (DASH, MHQ). Implant survival and complications were the primary endpoints. RESULTS: 10 Elektra and 21 Moovis prostheses were implanted between 2009 and 2019 with a mean follow-up of 74.2 months in the Elektra and 41.4 months in the Moovis group. The average patients' age at surgery was 64 years. Postoperative pain levels (VAS 0-10) were below 2 at rest and under stress in both groups. Grip/pinch strength and range of motion showed results comparable to the contralateral hand. Opposition was excellent with an average Kapandji index of 9.6 in both groups. Elektra achieved slightly better functional scores in the DASH and MHQ score. Satisfaction was high in both groups, and 96% of the patients would recommend the procedure. Metacarpophalangeal hyperextension > 15° was seen in 3 patients per group preoperatively and was corrected to < 5° post-surgery. 3 Elektra prostheses were revised due to cup loosening and dislocation for cup and/or neck replacement or secondary trapeziectomy. 1 Moovis prosthesis was revised with an exchange of the neck to a larger size due to restricted movement. After the mean follow-up of 7.9 years in Elektra and 3.5 years in MOOVIS, cumulative survival was 68.6% vs. 95.2%, respectively. CONCLUSIONS: In this mid- to long-term retrospective analysis, total joint arthroplasty in primary trapeziometacarpal joint arthritis results in low pain levels, excellent mobility and clinical function. Patient satisfaction is overall high. While revision due to cup loosening occurred more often in patients with single-mobility implants, no cases of dislocation or loosening of components were observed in the dual-mobility group. TRIAL REGISTRATION: The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of the Medical Faculty of Heidelberg University, reference number S-150/2020.

Arthrodesis of distal interphalangeal and thumb interphalangeal joint: a retrospective cohort study of 149 cases.

BACKGROUND: Arthrodesis of finger joints is often the last line of treatment of severe pain due to osteoarthritis, rheumatoid arthritis, or mallet finger. At the Department of Orthopedic and Hand Surgery, Örebro University Hospital (ÖUH) in Sweden, the Kirschner-wire technique was standard until 2020, when the headless compression screw technique was introduced as a complement. There is no consensus on which method is superior. The purpose of this study was to examine the outcomes and complications associated with distal interphalangeal (DIP) joint and thumb interphalangeal (IP) joint arthrodesis, and to see whether these correlated with patient-dependent and treatment-related factors. METHODS: In a retrospective cohort study, we evaluated a total of 149 consecutive arthrodeses (118 DIP joint and 31 thumb IP joint) performed between 2012 and 2022. The primary outcome was risk factors for complications after arthrodesis. RESULTS: Osteoarthritis was the most common indication (56%) for arthrodesis. The majority of the patients were females (74%), and the median age was 62 (range 18-86). The complication frequency was 35%, with infection being the most common (25%). Time to completed follow up was < 12 weeks in the majority of the cases (58%). There were no significant differences in complication rate between the 136 joints operated using Kirschner wire and the 13 joints operated using headless compression screws. There was no significant increased risk of complications among smokers or patients with rheumatoid arthritis. Diabetes and surgeon experience had a significant influence on the risk of complication (p = 0.036 and p = 0.006, respectively). CONCLUSIONS: Osteoarthritis was the most common indication for arthrodesis and postoperative complications occurred at a rate similar to that reported in the existing literature. Diabetes and surgeon experience were identified as factors increasing the risk of postoperative complications in these DIP/thumb IP joint arthrodeses. However, there was no significant difference between the two techniques (Kirschner wire and headless compression screws) regarding complications. Further studies are needed in order to determine the optimal type of operation and choice of implant. TRIAL REGISTRATION: Researchweb CRIS #280,998, 26th of July 2023.

Radiographic features and subtypes of congenital thumb duplication type C3 according to Wu et al. and their potential implications for surgical management: new classification and preliminary results.

BACKGROUND: Wu et al. introduced a modified radiographic system that allows classification of all forms of CTD with excellent interobserver and intraobserver reliability. No study to date has evaluated the radiographic characteristics of Wu et al. type C3 CTD with osseous attachment at the level of the metacarpal. OBJECTIVE: This study aimed to evaluate the radiographic features of type C3 CTD according to the system of Wu et al., to describe the different anatomical subtypes of the duplication, and to propose a categorization approach to distinguish diverse surgical strategies based on the radiographic anatomy of this specific subtype of duplication. METHODS: We performed a retrospective analysis of 215 patients (221 thumbs) diagnosed with Wu et al. type C3 CTD at our Institution between 2015 and 2021. We evaluated all CTDs by examining the alignment of the interphalangeal (IP) and metacarpophalangeal (MP) joints and by assessing the presence of abnormal hypertrophic epiphysis of the primary thumb on posteroanterior (PA) radiographs. The proposed classification system has four types: Type I with good alignment of both MP and IP joints, Type II with ulnar deviation of the MP joint, Type III with radial deviation in the MP joint and Type IV with abnormal hypertrophic epiphysis of the distal phalanx of the main thumb with ulnar deviation of the IP joint with or without ulnar deviation of the MP joint. RESULTS: There were 140 male and 75 female patients with CTD (221 thumbs). There were 65 left, 144 right and 6 bilateral forms. The right-to-left, male-to-female and unilateral-to-bilateral ratios were 2.2:1, 1.9:1 and 35.8:1 respectively. The mean age at surgery was 22.3 ± 11.8 months (range, 8-80). The proposed classification system allowed the classification of all CTDs (n = 221). Specifically, 53 fingers were classified as Type I (24%), 136 as Type II (61.5%), 21 as Type III (9.5%), and 11 as Type IV (5%). CONCLUSION: The proposed system is based on radiographic pathoanatomy and complements that of Wu et al. by identifying four distinct subtypes of deformity. It has the potential to improve inter-professional communication and guide surgery in patients with Wu et al. type C3 CTD. However, our results are preliminary and further research is needed to validate them. LEVEL OF EVIDENCE: III.

MRI spectrum of injuries to the thumb metacarpophalangeal joint ulnar collateral ligament with a proposed expanded classification of injuries in American football players.

Injuries to the ulnar collateral ligament of the thumb metacarpophalangeal joint are of both historic and modern interest for athletes and non-athletes alike. The thumb metacarpophalangeal joint requires stability in both flexion and extension utilizing a combination of static and dynamic stabilizers. This article reviews the magnetic resonance imaging categorization of thumb ulnar collateral ligament injuries and proposes two additional injury patterns seen in high-level and professional athletes who play American football. In addition to the direct magnetic resonance imaging findings in collateral ligament tears, secondary findings of rotation and subluxation can be seen at the thumb metacarpophalangeal joint due to the altered physiologic forces on the joint. Internal brace augmentation via suture tape of a traditional ulnar collateral ligament repair is a novel surgical technique that provides protection during initial healing and the ensuing remodeling phase following repair or reconstruction, resulting in a faster return to play.

Hybridized deep learning goniometry for improved precision in Ehlers-Danlos Syndrome (EDS) evaluation.

BACKGROUND: Generalized Joint Hyper-mobility (GJH) can aid in the diagnosis of Ehlers-Danlos Syndrome (EDS), a complex genetic connective tissue disorder with clinical features that can mimic other disease processes. Our study focuses on developing a unique image-based goniometry system, the HybridPoseNet, which utilizes a hybrid deep learning model. OBJECTIVE: The proposed model is designed to provide the most accurate joint angle measurements in EDS appraisals. Using a hybrid of CNNs and HyperLSTMs in the pose estimation module of HybridPoseNet offers superior generalization and time consistency properties, setting it apart from existing complex libraries. METHODOLOGY: HybridPoseNet integrates the spatial pattern recognition prowess of MobileNet-V2 with the sequential data processing capability of HyperLSTM units. The system captures the dynamic nature of joint motion by creating a model that learns from individual frames and the sequence of movements. The CNN module of HybridPoseNet was trained on a large and diverse data set before the fine-tuning of video data involving 50 individuals visiting the EDS clinic, focusing on joints that can hyperextend. HyperLSTMs have been incorporated in video frames to avoid any time breakage in joint angle estimation in consecutive frames. The model performance was evaluated using Spearman's coefficient correlation versus manual goniometry measurements, as well as by the human labeling of joint position, the second validation step. OUTCOME: Preliminary findings demonstrate HybridPoseNet achieving a remarkable correlation with manual Goniometric measurements: thumb (rho = 0.847), elbows (rho = 0.822), knees (rho = 0.839), and fifth fingers (rho = 0.896), indicating that the newest model is considerably better. The model manifested a consistent performance in all joint assessments, hence not requiring selecting a variety of pose-measuring libraries for every joint. The presentation of HybridPoseNet contributes to achieving a combined and normalized approach to reviewing the mobility of joints, which has an overall enhancement of approximately 20% in accuracy compared to the regular pose estimation libraries. This innovation is very valuable to the field of medical diagnostics of connective tissue diseases and a vast improvement to its understanding.

High Fracture Rate of AVANTA Silicone Implant Following Arthroplasty of the Thumb MCP Joint of Rheumatoid Arthritis Patients with Boutonniere Deformities.

We retrospectively investigated the mid-term outcomes of arthroplasty using the AVANTA silicone implant for thumb metacarpophalangeal (MCP) joints with boutonniere deformity in patients with rheumatoid arthritis (RA). This study involved 36 thumbs of 33 RA patients with a mean follow-up period of 5.1 years (range, 2.0-13.3). Postoperatively, the mean extension was significantly increased and the mean flexion was significantly decreased (p<0.001, p<0.001, respectively), resulting in the mean arc of range of motion (ROM) shifting in the direction of extension after surgery. Implant fracture was observed in 10 thumbs (28%), and 4 of these (11%) underwent revision surgery. The survivorship with implant fracture and revision surgery as endpoints were 73.4% and 91.8% at 5 years, respectively. The preoperative arc of ROM and the postoperative flexion range of the implant-fracture group were significantly greater than those in the no-implant-fracture group (p=0.039, 0.034, respectively). These results suggest the importance of patient education and careful rehabilitation to prevent excessive flexion. Overall, the AVANTA silicone implant showed a relatively high rate of implant fracture at our institute.

U-shaped kirschner wire transfixation: effective treatment for Skier's thumb.

BACKGROUND: Skier's thumb is a type of injury to the ulnar collateral ligament of the metacarpophalangeal joint of the thumb, which can result in bone fragmentation and joint instability. OBJECTIVE: The objective of this study was to compare the traditional Kirschner wire fixation method with the U-shaped Kirschner wire method for treating small bone fragments with displacement, rotation, or instability in skier's fractures. METHOD: A retrospective study was conducted on 30 patients with skier's thumb who were treated at Tianjin Hospital from January 2019 to December 2021. Patients were divided into two groups: Group A received traditional Kirschner wire fixation, while Group B received U-shaped Kirschner wire fixation. Functional assessments and complications during the perioperative period were evaluated. RESULTS: Both surgical methods significantly reduced postoperative pain and increased joint range of motion. Group B had a lower incidence of pain during follow-up and showed significant functional improvement in Tip-pinch and Grip tests compared to Group A. U-shaped Kirschner wire fixation significantly reduced complications during the perioperative period. CONCLUSION: The U-shaped Kirschner wire internal fixation is a safe and effective treatment for the thumb proximal phalanx base ulnar side avulsion fracture.

The Effects of Radial Longitudinal Deficiency on Long-Term Use of the Thumb in Pediatric Patients Following Index Pollicization.

PURPOSE: To assess the effect of radial longitudinal deficiency on the function of pollicized digits as determined by the Thumb Grasp and Pinch (T-GAP) assessment. METHODS: We retrospectively evaluated 25 hands with thumb hypoplasia that underwent index finger pollicization. Patients were followed for an average of 10.4 years. Hands were divided by severity into two groups: no or mild radial longitudinal deficiency (RLD) (Group 1 = 16) and moderate to severe RLD (Group 2 = 9). We collected demographic information and completed physical examination measures, including hand strength, elbow, wrist, and hand range of motion, the Kapandji opposition score, active grasp span, and T-GAP total score. RESULTS: Patients with moderate to severe forms of RLD had stiffer long fingers, lower Kapandji opposition scores, and limited active and passive range of motion for elbow flexion, wrist ulnar deviation, and pollicized thumb interphalangeal flexion. They had shorter forearms, decreased active grasp span, and fewer thumb creases at the interphalangeal thumb joint. In addition, the T-GAP total score was significantly lower when comparing the two groups. Children with mild dysplasia were able to achieve 32% of age-matched normal grasp strength. Patients with more severe radial dysplasia averaged 17% less grasp strength compared with children with mild dysplasia. Patients with moderate to severe RLD also had lower T-GAP total scores and strength measurements if they had limited wrist ulnar deviation. CONCLUSIONS: Individuals with moderate to severe RLD have unique anatomical factors that affect outcomes after pollicization. These individuals use their thumbs for fewer activities, have weaker grasp, and retain more primitive grasp patterns compared with those who have milder forms of RLD. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

A Prospective Randomized Pilot Study: One-Year Outcomes of Ligament Reconstruction Tendon Interposition Versus Suture Tape Suspensionplasty for Thumb Carpometacarpal Joint Arthritis.

PURPOSE: We performed a randomized controlled trial assessing patient-reported outcome measures following trapeziectomy with ligament reconstruction and tendon interposition (LRTI) or suture tape suspensionplasty (STS) for treatment of thumb carpometacarpal joint osteoarthritis. METHODS: Patients undergoing surgery for thumb carpometacarpal joint osteoarthritis were prospectively randomized to LRTI or STS. Outcome measures were collected at 2 weeks, 4 weeks, 3 months, and 1 year and included visual analog scale pain, Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity, return to work/activity, range of motion, grip/pinch strength, and complications. RESULTS: Thirty-one patients (32 thumbs) were randomized from 51 patients offered participation over two years. One-year follow-up was 97%. Both groups had a decrease in visual analog scale pain scores at all postoperative time points. The trajectory of postoperative Patient-Reported Outcomes Measurement Information System Upper Extremity scores was similar, and both groups achieved the meaningful clinically important difference for improvement in PROMIS Upper Extremity by three months. Grip strength was substantially increased in both groups at one year. Return to work/activity and surgical complications favored the LRTI group. CONCLUSIONS: Our study did not suggest any clinically relevant differences in the postoperative patient-reported outcome measures or objective clinical measurements between LRTI and STS, although LRTI patients had a faster return to work/activity and lower complication rates. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IIB.

Radiographic Features of the Metacarpal in Blauth Type III Thumb Hypoplasia.

PURPOSE: The purpose of this study was to investigate whether radiographs can be used to aid in the determination of Blauth IIIA and IIIB thumbs. METHODS: Six pediatric hand surgeons were asked to evaluate the radiographs of 77 thumbs and classify the thumb as IIIA or IIIB and indicate which morphologic features influenced their decision. Quantitative measurements and ratios of radiographs were obtained and compared between IIIA and IIIB thumbs. RESULTS: The radiographic features selected for type IIIA thumbs include near-normal length and near-normal width and for type IIIB thumbs, abnormally short, tapered proximal end, and round proximal end. The six surveyed surgeons reached consensus in 82% (63/77) of thumbs, and this matched the enrolling surgeon's classification in 77% (59/77) cases. The ratio of the length of the thumb metacarpal compared with the length of the index metacarpal was different between IIIA and IIIB thumbs (66% ± 0.08% and 46% ± 0.18%, respectively). The ratio of the width of the thumb metacarpal shaft at its narrowest aspect to the width of the thumb metacarpal base was notably different between IIIA and IIIB (68% ± 0.13% and 95% ± 0.28%, respectively). CONCLUSIONS: Near-normal length and near-normal width of the metacarpal were used to predict IIIA and abnormally short, abnormally narrow, and a round or tapered base of the metacarpal were used to predict IIIB classification. The length of the thumb metacarpal relative to the index metacarpal is on average 66% of the length of the index metacarpal in IIIA thumbs compared with 46% in IIIB thumbs. The width of the shaft of the thumb metacarpal at its narrowest is 68% of the width of the thumb metacarpal base in IIIA thumbs, indicating a flared base. In IIIB thumbs, the shaft width was on average 95% of the base width, indicating a tapered base. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic level III.

Thumb Metacarpophalangeal Joint Kinematics and Elongation of the Ulnar Collateral Ligament.

PURPOSE: The purpose of the study was to determine if the sphericity of the thumb metacarpophalangeal (MCP) joint influences the joint's rotational axis (RA) and elongation patterns of the ulnar collateral ligament (UCL). METHODS: Ulnar collateral ligament origins and attachments of 28 fresh-frozen cadaveric thumbs were marked with a radiopaque marker. Lateral radiographs were obtained in neutral and 20°, 40°, and 60° of flexion. The dorsal and palmar joint gap and the length of four different UCL portions were digitally measured in all flexion states. The RA was determined by the intersection of the midshaft axis of the proximal phalanx in neutral and flexion states. Sphericity of the MCP joint was assessed using morphometric parameters. Joints were grouped as round or flat. Differences in all measured parameters between groups were analyzed. RESULTS: During flexion, the dorsal joint gap increased by 322% in flat joints and 163% in round joints. The palmar joint gap decreased to 45% in flat joints and to 87% in round joints. The RA was at 29% of metacarpal height and 96% of metacarpal length in flat joints and at 40% of height and 86% of length in round joints. Maximum UCL elongation (111%) was noted at 40° flexion in the dorsal proper UCL in flat joints and at 60° flexion in the accessory UCL (117%) in round joints. CONCLUSIONS: In flat MCP joints, the RA is more dorsal and distal in the metacarpal head compared to round joints, resulting in a hinged flexion motion. Elongation of the UCL is highest at end flexion in round joints and highest at midflexion in flat joints. CLINICAL RELEVANCE: The different kinematics of flat and round MCP joints may contribute to the understanding of the pathophysiology of UCL ruptures. The propensity of this injury and the position in which they occur may be affected by the MCP joint morphology.

Complications and Unplanned Reoperation After Thumb Metacarpophalangeal Arthrodesis.

PURPOSE: Arthrodesis of the metacarpophalangeal (MCP) joint of the thumb is a common procedure to treat arthritis or instability. Studies reporting hardware complications and nonunion rates after thumb MCP joint arthrodesis report on small sample sizes. We aimed to describe the hardware complication rate, the nonunion rate, and the number of thumbs that achieve union among patients undergoing thumb MCP joint arthrodesis. METHODS: A database spanning 5 urban hospitals in a single metropolitan region in the United States was searched for patients who underwent thumb MCP joint arthrodesis between January 1, 2004 and January 1, 2020. After reviewing patient records, we identified 122 thumbs that underwent MCP joint arthrodesis and had a minimum follow-up of 90 days. The primary outcome was unplanned reoperation after hardware complications and nonunion. Second, the number of thumbs that achieved radiographic union was reported for the tension band and screw fixation arthrodesis group. RESULTS: Twenty-two (18%) out of 122 thumbs had hardware complications after thumb MCP joint arthrodesis, and 11 (9%) out of 122 thumbs developed a nonunion. Patients who underwent screw fixation arthrodesis had no events of hardware complications and subsequent hardware removal. The nonunion rate was 9/65 (14%) in the tension band arthrodesis group and 2 (4%) of 45 in the screw fixation arthrodesis group. Of the thumbs that had available radiographs to assess the healing of the arthrodesis, 34 (81%) of 42 were radiographically united in the tension band arthrodesis group and 29 (91%) of 32 in the screw fixation group. CONCLUSIONS: Our data suggest that screw fixation has fewer hardware complications and a lower reoperation rate than tension band arthrodesis. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognosis IV.

Patient-Reported and Clinical Outcomes After Tendon Autograft Reconstruction of the Thumb Ulnar Collateral Ligament.

PURPOSE: This study aimed to report clinical and patient-reported outcomes collected in a registry after thumb ulnar collateral ligament (UCL) reconstruction with a free tendon autograft. Furthermore, the patient-reported outcomes of patients with persistent instability after reconstruction and patients with concomitant metacarpophalangeal joint arthritis diagnosed during surgery were analyzed. METHODS: Patients undergoing reconstruction with a tendon autograft between December 2011 and February 2021 were included. Michigan Hand Outcomes Questionnaire (MHQ) scores at baseline were compared with those at 3 and 12 months after surgery. Stability was tested at 3 months after surgery. Tip and key pinch strength and metacarpophalangeal joint range of motion were measured at baseline and 12 months after surgery. RESULTS: We included 31 patients with thumb UCL insufficiency or failed UCL surgery who underwent reconstruction. The MHQ total score improved significantly from 62 at baseline to 75 at 3 months and continued to increase to 84 at 12 months after surgery. The MHQ function and pain scores improved significantly from intake to 3 and 12 months after surgery. Twenty-six of 31 patients (84%) regained postoperative metacarpophalangeal stability. Key pinch strength improved significantly 12 months after surgery from 5.2 kg at baseline to 6.4 kg at 12 months. The MHQ total, pain, and function scores of patients with persistent instability remained similar from baseline to 12 months after surgery. In four patients with metacarpophalangeal arthritis, the MHQ total and pain score improved significantly from baseline to 3 and 12 months after surgery. CONCLUSIONS: Patient-reported outcomes, including pain and function, improved after thumb UCL reconstruction with a tendon autograft. Although the sample size of patients with thumb metacarpophalangeal arthritis diagnosed during surgery was small, they reached adequate patient-reported outcomes at 12 months after surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.