Volar dislocation of the metacarpophalangeal joint of the thumb: open reduction and repair of the ulnar collateral ligament. A case report.

INTRODUCTION: metacarpophalangeal dislocations of the thumb are not very frequent injuries, it is necessary to know the anatomy of the region to know possible causes of interposition that prevent a closed reduction of this pathology. CASE PRESENTATION: we present the case of a 75-year-old woman with a post-traumatic metacarpophalangeal dislocation of the thumb that required open reduction and surgical repair. In this procedure, we performed reduction of the dislocation, mobilization of the interposed structures, repair of the capsule and reinsertion of the ulnar collateral ligament. The early mobilization protocol helped to obtain very good results. CONCLUSION: it is imperative to consider possible associated injuries during the acute phase to achieve optimal short, medium, and long-term outcomes for our patients. A comprehensive and proactive approach to diagnosis and treatment is vital in effectively addressing this pathology and minimizing its potential sequelae.

INTRODUCCIÓN: las luxaciones metacarpofalángicas del pulgar no son lesiones muy frecuentes, es necesario conocer la anatomía de la región para conocer posibles causas de interposición que impidan una reducción cerrada de esta patología. PRESENTACIÓN DEL CASO: presentamos el caso de una mujer de 75 años con luxación metacarpofalángica postraumática del pulgar que requirió reducción abierta y reparación quirúrgica. En este procedimiento realizamos reducción de la luxación, movilización de las estructuras interpuestas, reparación de la cápsula y reinserción del ligamento colateral cubital. El protocolo de movilización temprana ayudó a obtener muy buenos resultados. CONCLUSIÓN: es imperativo considerar posibles lesiones asociadas durante la fase aguda para lograr resultados óptimos a corto, mediano y largo plazo para nuestros pacientes. Un enfoque integral y proactivo del diagnóstico y tratamiento es vital para abordar eficazmente esta patología y minimizar sus posibles secuelas.

Outcomes of Arthrodesis of the Metacarpophalangeal Joint of the Thumb for Sequelae of Collateral Ligament Injuries: A Series of 18 Cases with 6-Year Follow-Up.

Background: Untreated or insufficiently treated collateral ligament injuries of the thumb metacarpophalangeal (MP) joint can lead to instability or even osteoarthritis. Arthrodesis is one of the treatment options available for the treatment of the sequelae of collateral ligament injuries. The objective of our study was to evaluate the radiological, clinical and functional outcomes of MP joint arthrodesis performed for sequelae of collateral ligament injuries. Methods: We conducted a retrospective, single-centre study and reviewed the files of patients who had a thumb MP joint arthrodesis following a collateral ligament injury between 2011 and 2019. We collected patient's demographic data and the results of the radiological and clinical examinations. Results: Eighteen patients were included in the study. The average age was of 53.6 years and the time between injury to arthrodesis averaged 7 years. Four patients (22%) had nonunion. In the remaining 14 patients with solid union at an average of 72 months follow-up, the visual analogue pain score at rest was 0.14, the thumb opposition was 82%, grip strength 85%, tip pinch 92% and key pinch 79% of the contralateral side. Conclusions: The clinical and functional results of patients with a successful arthrodesis are satisfactory with restoration of good grip and pinch strength. Despite a lack of thumb MP joint flexion, stability allowed force transmission and may be preferred for manual workers. Level of Evidence: Level IV (Therapeutic).

Metacarpophalangeal joint reconstruction using a costal osteochondral graft: A case report.

RATIONALE: The conventional treatment of giant cell tumors is intralesional curettage with local adjuvant therapy. Because hand tumors have a high local recurrence, the primary goal for treating tumors of the hand is to eradicate the lesion. PATIENT CONCERNS: To preserve the metacarpophalangeal (MCP) joint function as well as avoid further recurrence after surgery. DIAGNOSES: The giant cell tumor invades the patient's MCP joint in an index proximal phalanx. INTERVENTIONS: Using computer-aided design and three-dimensional printing techniques, we reformed the original shapes of the MCP joint and its peripheral bone to replica models. The surgeon then performed an en bloc resection and proximal phalanx with MCP joint reconstruction by fabricating the patient's costal osteochondral graft during the operation. OUTCOMES: After 6 months of rehabilitation, the patient's finger functions could pinch and grasp objects naturally. At the 1-year follow-up, the range of motion of the MCP, proximal interphalangeal, and distal interphalangeal joints improved from flexion of 35° to 60°, 75° to 85°, and 60° to 80°, respectively. The hand function achieved the mean performance of non-preferred hands for young females at the postoperative 3-year follow-up. LESSONS: The customized prototyping technique has the potential to replica the original patient's bony graft to reach the goal of minimizing the defects at the donor site and maximizing the function of the reconstructed MCP joint.

Novel figure-of-eight reconstruction with free tendon graft for unrepairable collateral ligament of the thumb metacarpophalangeal joint.

OBJECTIVES: This study aimed to report surgical technique and clinical outcomes for a novel figure-of-eight collateral ligament reconstruction technique using palmaris longus autograft for chronic irreparable collateral ligament injury of the thumb metacarpophalangeal joint. MATERIAL AND METHODS: The Jobe elbow collateral ligament reconstruction method was adapted for thumb metacarpophalangeal joint collateral ligament reconstruction. Sixteen reconstructions (7 ulnar collateral ligament, 9 radial collateral ligament) using palmaris longus autograft were reviewed retrospectively. Surgery was performed at a mean 12 months post-injury. All 16 patients were followed up for more than 1 year. Metacarpophalangeal joint radial and ulnar deviation, metacarpophalangeal and interphalangeal joint range of motion, key pinch and grip strength, Glickel functional grade and QuickDASH score were evaluated. RESULTS: Preoperative radial or ulnar deviation improved from 19.3° to 5.3° postoperatively. Metacarpophalangeal range of motion improved from 31.5° to 46.6°, and interphalangeal range of motion from 48.4° to 65.6°. Preoperative key pinch and grip strength were respectively 49% and 81% of contralateral values and improved to 82% and 87%. On Glickel grade, 9 cases were excellent and 7 good. CONCLUSION: The novel Jobe-like figure-of-eight reconstruction technique using palmaris longus graft was useful for reconstructing irreparable thumb metacarpophalangeal joint instability without an incision on the opposite side or an additional implant. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Surface wear of PyroCarbon implant in metacarpophalangeal joint arthroplasty without radiographic abnormality: A case report.

CASE: A 54-year-old male with osteoarthritis of the right long finger metacarpophalangeal joint underwent PyroCarbon joint arthroplasty. Seven years later the patient presented for metacarpophalangeal joint swelling and pain. The workup was benign, without signs of implant complication or osseous abnormality. He underwent washout and two-stage revision, where gross implant wear and debris not demonstrated by radiograph were found. He then returned to the operating room for reimplantation of a PyroCarbon implant. CONCLUSION: This case demonstrates a novel presentation of aseptic PyroCarbon implant failure in the hand without radiographic abnormality that can alter operative management by reducing operating room returns.

Kinematic Investigation of Healthy, Arthritic, and Postsurgery Thumbs: Is the Metacarpophalangeal Joint the Gateway to Carpometacarpal Arthritis?

The thumb carpometacarpal (CMC) joint is one of the most likely joints to develop osteoarthritis (OA). If conservative treatments fail to alleviate symptoms, surgery may be pursued. Kinematic outcomes of CMC surgery techniques have been described, but current tools have limitations in capturing motion abilities. The goals of this study were (1) develop a new and robust set of kinematic outcome measures, and apply them to (2) a cohort of younger and older control individuals without CMC OA to determine age and sex-related changes, and (3) a cohort of participants with CMC OA before, 3 months, and 6 months after undergoing thumb ligament reconstruction with tendon interposition surgery to detect the impacts of surgery. 52 (26 males, 26 females) control and 18 (3 males, 15 females) surgical participants were tested. Kinematics were investigated using motion capture by mapping the three-dimensional motion space of the whole thumb, and two-dimensional motion boundaries of the metacarpal (MC) and proximal phalange (PP). Visual analog pain score was recorded. Older control participants had shifted regions of motion compared to younger participants (p ≤ 0.027), suggesting asymptomatic CMC wear. Control females had 31% more metacarpophalangeal (MCP) motion than control males (p = 0.013), which could alter loading paths through the CMC joint and increase OA risk. Pain at 6 months postsurgery was 72% less than presurgery (p < 0.001), but motion abilities were 20-28% less than presurgery (p ≤ 0.074) and 24-40% less than control participants (p ≤ 0.066). These techniques have the possibility of identifying presymptomatic motion changes, including those at the metacarpophalangeal joint in CMC OA progression.

Biological Versus Nonbiological Reconstruction of the Ulnar Collateral Ligament of the Thumb Metacarpophalangeal Joint: A Retrospective Study.

PURPOSE: The purpose of this study was to compare clinical and radiologic outcomes of biological ligament reconstruction (BLR) versus nonbiological ligament reconstruction (NBLR) for chronic injuries involving the ulnar collateral ligament of the thumb's metacarpophalangeal joint. METHODS: Forty-two patients who underwent static BLR (n = 24) or NBLR (n = 18) were included in this retrospective analysis. Preoperative, postoperative, and contralateral thumb measurements (clinical evaluation, radiographs, and subjective outcome questionnaires) were compared over a mean of 38 months of follow-up. RESULTS: Average postoperative thumb metacarpophalangeal and interphalangeal joint ranges of motion were 2° to 54° and 0 to 71°, respectively, for BLR and 0° to 58° and 0° to 71°, respectively, for NBLR. Average grip and pinch strengths, relative to the unaffected hand, were 102% and 84% versus 103% and 89%, respectively. All patients demonstrated stability with a firm end point, compared with the unaffected thumb. The average Quick Disabilities of the Arm, Shoulder, and Hand score among all patients was 12 for the disability/symptom module, 0 for the sports module, and 17 for the work module. Stiffness was reported among four patients, and no patient sustained wound-related issues or other complications. CONCLUSIONS: Nonbiological ligament reconstruction of the thumb ulnar collateral ligament generates short-term outcomes comparable with those of BLR, potentially allowing for expedited recovery and rehabilitation. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

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.

The Application of Sesamoid Position in Diagnosing Thumb Metacarpophalangeal Joint Dorsal Dislocation: A Retrospective Study.

OBJECTIVES: The position of sesamoid of thumb metacarpophalangeal (MCP) joint changed clearly when the joint was dislocated dorsally. However, the significance of sesamoid location in diagnosing joint dislocation was unclear. The present study aimed to explore the positional relationship between sesamoid bone and thumb metacarpophalangeal joint in normal and dorsal dislocation joints. METHODS: Between January 2018 and August 2023, we collected 60 isometric plain films from sixty outpatients and reviewed 56 anisometric plain films from twenty-eight emergency patients with dorsal dislocation of thumb MCP joint at Tianjin Hospital, then took measurements on the hand X-ray images. The sesamoid length on its longitudinal axis was defined as DP, the distance between the distal edge of sesamoid and thumb MCP joint was defined as DJ, and the ratio of DJ and DP was R. An independent-samples t-test and paired-samples t-test was utilized to analyze difference among data groups. RESULTS: The 60 isometric images were from 30 male and 30 female outpatients with normal bone structure in their hands, and the 56 anisometric images of the 28 emergency patients included both preoperative and postoperative materials. Among the outpatients, the actual distance between the distal edge of sesamoid and thumb MCP joint space (DJ) was 2.09 mm and 1.40 mm in males and females, respectively. The authentic average length of sesamoid (DP) was 4.46 mm in males and 4.22 mm in females. The average value of R (the ratio of DJ and DP) in males and females was 0.49 and 0.34, respectively. There were gender-related statistical differences in DJ (p < 0.01) and R (p=0.01), but no statistical difference in DP (p > 0.05). For the 28 emergency patients, the mean value of R was -0.47 before joint reduction and 0.58 after joint reduction, with statistical difference between them (p < 0.01). CONCLUSIONS: There was significant difference in the relative position between sesamoid and thumb MCP joint when joint dislocation and joint reduction. The distal edge of sesamoid beyond thumb MCP joint could be an evidence in diagnosing joint dorsal dislocation. The distal edge of sesamoid below thumb MCP joint could be an evidence of joint reduction.

Long-Term Implant Fracture Rates Following Silicone Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis.

PURPOSE: The primary objective of this study was to compare the long-term survival rates of silicone metacarpophalangeal (MCP) arthroplasties between two major implants in patients with rheumatoid arthritis, using implant fracture as an end point. We also evaluated the difference in postoperative function between patients with fractured and intact implants as a secondary objective. METHODS: A retrospective cohort study was conducted on 372 fingers of 133 hands that underwent silicone MCP arthroplasty between January 2000 and June 2019 (mean follow-up, 7.6 years). The survival rates of Swanson-type and Sutter-type implants were compared, using implant fracture as the end point after a radiographic evaluation. Clinical measures and upper limb functional assessments using the Disabilities of the Arm, Shoulder, and Hand (DASH) score were performed in the nested cohort. RESULTS: The 10.6-year survival rates for implant fracture of Swanson- and Sutter-type implants were 86.2% and 9.4%, respectively, with significantly higher survival noted for Swanson-type implants. The Sutter-type implant showed increased susceptibility to fracture in all four fingers compared to the Swanson-type implant. Implant fractures were primarily observed at the stem-hinge junction. There were no significant differences in upper limb function between the fractured and intact implant groups. CONCLUSIONS: Sutter-type implants were found to be more prone to fracture compared with Swanson-type implants. However, implant fractures did not significantly affect upper limb function. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognosis IV.

Painful snapping of the middle finger caused by hyperplasia of the ulnar lateral band: A case report.

Snapping of fingers can be caused by pathologies such as stenosing flexor tenosynovitis. However, snapping symptoms in the metacarpophalangeal (MP) joint caused by hypertension and hyperplasia of the lateral band are rare. We present a 26-year-old female with symptoms of painful snapping of the middle finger. When the finger was actively flexed from the hyperextension of the MP joint, the ulnar lateral band was prominent, and a snapping phenomenon occurred. The cause of the snapping finger was considered to be tightness of the ulnar lateral band, and surgery was planned. Intraoperatively, the ulnar lateral band was tense and hyperplastic. The snapping phenomenon disappeared immediately after the resection of the lateral band. It is important to consider this condition as one of the differential diagnoses of snapping finger when the patient complains of an atypical snapping phenomenon.

Locking of the metacarpophalangeal joint: A comprehensive review of the literature.

Locked metacarpophalangeal joint is an uncommon phenomenon with many possible etiologies. Diagnosis can be difficult because of the many more common pathologies (trigger finger, sagittal band lesion, etc.) that can lead to a clinical picture that may resemble the locked metacarpophalangeal joint. Once the differential diagnoses have been eliminated, the etiology of this blockage must be determined and the surgical procedure must be oriented. The origin of the problem is often difficult to determine, especially since standard imaging tests are often not very informative. Several clinical forms are possible, with blockages in extension or flexion, but which will have a disabling functional impact on the overall function of the hand. Currently, there is no gold standard for the management of this condition. In this study, we performed a review of the literature in order to better understand the different possible etiologies but also to analyze the different diagnostic and therapeutic management. LEVEL OF EVIDENCE: IV.

The influence of a tension band fixation as an adjunct for arthrodesis of the metacarpophalangeal joint in the horse.

OBJECTIVES: To determine the influence of a stainless-steel cable (SSC) tension band fixation as an adjunct to a locking compression plate (LCP) for arthrodesis of the equine metacarpophalangeal (MCP) joint. STUDY DESIGN: Experimental. An ex vivo biomechanical paired equine cadaver limb study. SAMPLE POPULATION: Five MCP joint pairs were collected from adult Thoroughbred horses, euthanized for reasons unrelated to orthopedic disease. METHODS: Each pair of MCP joints were randomly implanted with either a dorsally placed 5.5 mm LCP and a palmarly placed 2.0 mm SSC or a dorsally placed 5.5 mm LCP alone. Each construct was tested in cyclic loading followed by single cycle to failure in axial compression. Displacement at a target load of 1 kN over 3600 cycles at 1 Hz was recorded prior to single cycle to failure testing. RESULTS: In cyclic testing, displacement was not significantly different between the first and last 5% of testing cycles regardless of construct. Maximum displacement of each construct during cyclic testing was <1.1 mm. In single cycle testing, the observed yield point did not reveal any difference between LCP and LCP-SSC (p = .440). The maximum load at failure was significantly higher in LCP-SSC compared to constructs with the LCP alone (p = .046). CONCLUSION: The addition of the SSC to the LCP did not statistically affect construct displacement during cyclic loading or construct yield load during subsequent single cycle to failure. CLINICAL SIGNIFICANCE: This study provided much needed information regarding the necessity of a tension band SSC application in the arthrodesis of the MCP/MTP joint in horses.

The silicone metacarpophalangeal joint arthroplasty: An in-vitro analysis.

BACKGROUND: Silicone is still the gold standard implant in metacarpophalangeal arthroplasty. Whereas the clinical results are acceptable, in follow-ups with >10 years, high rates of implant fracture are common, and 5 to 7% of implants required revision. This work's purpose is to analyse the hypothesis that the joint flexion amplitude has a relevant effect on bone strain level, implant stress and bone-implant micromotion, which can reflect an increase in the risk of bone resorption/fatigue failure, implant fracture and osteolysis. METHODS: To experimentally predict the cortical loading behaviour, composite metacarpals and proximal phalanges were used in intact and implanted states. A finite element model was developed to evaluate the structural behaviour of cancellous bone and implant. This model was validated by comparing cortical strain and load-displacement curve with experimental measurements. FINDINGS: Bone strain changes between the intact and the implanted states showed a load transfer effect from the cortical to the cancellous bone that increases significantly with the flexion's amplitude rise. The peak implant stress occurred in the flexion amplitudes further away from the implant neutral angle. The highest implant pistoning motion and the highest phalanx cancellous-bone strain occurred simultaneously at the maximum flexion amplitude. INTERPRETATION: Limiting joint flexion range will be helpful to reduce the strain-shielding effect on cortical bone, minimizing the overload effect on cancellous bone and decreasing the stress levels and the pistoning motion on the implant, ultimately contributing to the longevity of silicone arthroplasty.

Satisfactory thumb metacarpophalangeal joint stability after ligament reconstruction with flexor digitorum superficialis in children with radial longitudinal deficiency.

We investigated thumb joint stability and patient-reported and functional outcomes a minimum of 1 year after flexor digitorum superficialis opponensplasty and ligament reconstruction in 23 thumbs of 20 consecutive children with radial longitudinal deficiency. In total, 15 thumbs had preoperative multidirectional instability in the metacarpophalangeal joint. We reconstructed 22 ulnar and 16 radial collateral ligaments. At follow-up, all the metacarpophalangeal joints were stable ulnarly. Seven metacarpophalangeal joints were unstable radially despite ligament reconstruction but had no related complaints. We recommend the flexor digitorum superficialis opponensplasty as a safe and reliable procedure in hypoplastic thumbs to create stability and augment thumb strength.Level of evidence: IV.

Techniques for Continuous Catheter Irrigation of a Septic Metacarpophalangeal Joint.

Septic arthritis of the metacarpophalangeal joint (MCPJ) compromises 9% of hand infections in Singapore. Common surgical treatment is open arthrotomy and joint washout. The wound is often left open for drainage postoperatively. Repeated debridement and secondary closure are frequently needed after the index surgery. We describe a method of continuous catheter irrigation of septic MCPJ joint using an infant feeding catheter. This method provides great infection clearance to avoid repeated debridement and allows primary closure of the wound to avoid secondary closure. This method also significantly reduces postoperative pain so that to facilitate early mobilization of the joint, which is crucial for functional recovery. We illustrate the techniques of this procedure and key points of postoperative management in the ward with case examples to demonstrate its simplicity, safety, and efficacy in treating MCPJ septic arthritis.

[A V-Y shaped flap with digital artery nerve at metacarpophalangeal joint was used to repair the defect of middle and distal phalanx].

OBJECTIVE: To explore a surgical method for the reconstruction of volar soft tissue defect and sensory and vascular repair in middle and far phalangeal digits. METHODS: From January 2016 to January 2020, a total of 14 patients , 9 males and 5 females, ages ranging from 22 to 69 years old, and with volar soft tissue defects in the middle and distal digits 2 to 4, underwent surgical reconstruction using the V-Y shaped flap with digital artery and nerve at the metacarpophalangeal joint. The defect area was (2.0~2.5) cm×(1.5 ~2.0) cm. The procedure involved the harvest of a V-Y shaped flap with the digital artery and nerve from the metacarpophalangeal joint. Flap design, dissection of blood vessels and nerves, and anastomosis with the digital artery and nerve were performed according to a standardized protocol., Functional exercise of affected finger was initiated 3 weeks postoperatively. Subsequent assessments were conducted to evaluate finger pulp sensation, shape and other relevant parameters. According to the upper extremity functional evaluation standard set up by Hand Surgery Branch of Chinese Medical Association, the surgical outcomes were evaluated. RESULTS: All 14 cases demonstrated successful tissue transplantation, , with immediate recovery of sensation observed in 10 cases with distal finger pulp defects. Four patients with middle phalangeal defects experienced gradual sensory recovery within 2 to 3 months postoperatively. Thirteen patients were followed up for a mean duration of (8.8 ± 4.49) months, during which satisfactory outcomes were observed. The average two-point resolution of the finger pulp was 4-6mm, and sensory function evaluation yielded a score of S3 or above. Patients exhibited realistic finger shape, normal skin color and temperature, good wear resistance, and cold resistance. Furthermore, finger joint function was essentially normal. CONCLUSION: The V-Y shaped flap with digital artery and nerve at the metacarpophalangeal joint offers a suitable solution for repairing the defect of the middle or distal phalangeal finger. This technique is characterized by its simplicity, low risk, and favorable outcomes, including restored finger shape, blood supply and sensation. Moreover, high patient satisfaction was achieved.

Implant-free anatomical reconstruction of thumb metacarpophalangeal joint chronic ulnar collateral ligament injuries.

A technique is described to treat chronic instability of the metacarpophalangeal joint of the thumb caused by rupture of the ulnar collateral ligament using a palmaris longus tendon graft without implants. Good results were obtained in eight patients.

Patient-Reported Outcomes and Function After Surgical Repair of the Ulnar Collateral Ligament of the Thumb.

PURPOSE: The purpose of this study was to report prospectively collected patient-reported outcomes of patients who underwent open thumb ulnar collateral ligament (UCL) repair and to find risk factors associated with poor patient-reported outcomes. METHODS: Patients undergoing open surgical repair for a complete thumb UCL rupture were included between December 2011 and February 2021. Michigan Hand Outcomes Questionnaire (MHQ) total scores at baseline were compared to MHQ total scores at three and 12 months after surgery. Associations between the 12-month MHQ total score and several variables (i.e., sex, injury to surgery time, K-wire immobilization) were analyzed. RESULTS: Seventy-six patients were included. From baseline to three and 12 months after surgery, patients improved significantly with a mean MHQ total score of 65 (standard deviation [SD] 15) to 78 (SD 14) and 87 (SD 12), respectively. We did not find any differences in outcomes between patients who underwent surgery in the acute (<3 weeks) setting compared to a delayed setting (<6 months). CONCLUSIONS: We found that patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline. We did not find an association between injury to surgery time and lower MHQ total scores. This suggests that acute repair for full-thickness UCL tears might not always be necessary. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Thumb metacarpophalangeal joint morphology and reconstruction of the ruptured ulnar collateral ligament.

Studies on graft reconstruction techniques for ruptured thumb metacarpophalangeal (MCP) ulnar collateral ligaments (UCL) do not consider the variety of MCP joint morphology. Optimal reconstruction method for flat MCP joints is therefore unclear. Twenty-four fresh-frozen, human thumbs were tested for flexion, extension and valgus stability of the MCP joint. After resection of the UCL, four reconstruction methods, differing in the metacarpal origin and phalangeal attachment, were performed on each specimen, which were then tested again in the same way. Specimens were grouped as 'round' or 'flat' depending on morphometric parameters and group differences were analysed. In flat joints, only the non-anatomical Glickel reconstruction and a modified Fairhurst reconstruction maintained normal mobility and stability. In round joints, only the Glickel reconstruction maintained normal mobility and stability. The original Fairhurst method and a modification with the origin palmar in the metacarpus were disadvantageous in both flat and round joints.