Biomechanical analysis of plate versus K-wire fixation for metacarpal shaft fractures with wedge-shaped bone defects.

BACKGROUND: Metacarpal shaft fracture is a common type of hand fracture. Numerous studies have explored fixing transverse fractures in the midshaft of the metacarpal bone. However, this section of the metacarpal bone is often susceptible to high-energy injury, resulting in comminuted fracture or bone loss. In such cases, wedge-shaped bone defects can develop in the metacarpal shaft, increasing the difficulty of performing fracture fixation. Notably, the research on this type of fracture fixation is limited. This study compared the abilities of four fixation methods to fix metacarpal shaft fractures with wedge-shaped bone defects. METHODS: In total, 28 artificial metacarpal bones were used. To create wedge-shaped bone defects, an electric saw was used to create metacarpal shaft fractures at the midshaft of each bone. The artificial metacarpal bones were then divided into four groups for fixation. The bones in the first group were fixed with a dorsal locked plate (DP group), those in the second group were fixed with a volar locked plate (VP group), and those in the third group were fixed by combining dorsal and volar locked plates (DP + VP group), and those in the fourth group were fixed with two K-wires (2 K group). Cantilever bending tests were conducted using a material testing machine to measure yielding force and stiffness. The four groups' fixation capabilities were then assessed through analysis of variance and Tukey's test. RESULTS: The DP + VP group (164.1±44.0 N) achieved a significantly higher yielding force relative to the 2 K group (50.7 ± 8.9 N); the DP group (13.6 ± 3.0 N) and VP group (12.3 ± 1.0 N) did not differ significantly in terms of yielding force, with both achieving lower yielding forces relative to the DP + VP group and 2 K group. The DP + VP group (19.8±6.3 N/mm) achieved the highest level of stiffness, and the other three groups did not differ significantly in terms of stiffness (2 K group, 5.4 ± 1.1 N/mm; DP group, 4.0 ± 0.9 N/mm; VP group, 3.9 ± 1.9 N/mm). CONCLUSIONS: The fixation method involving the combined use of dorsal and volar locked plates (DP + VP group) resulted in optimal outcomes with respect to fixing metacarpal shaft fractures with volar wedge bone defects.

Evaluation of treatment processes in childhood fifth metacarpal bone (Boxer) fractures with QuickDASH scoring system.

OBJECTIVE: Metacarpal fractures are one of the most common orthopedic injuries seen in emergency departments. Despite this, only a few data have been published about the epidemiology of metacarpal fractures. Simple radiographs are the standard imaging modality used to diagnose boxer fractures and determine the degree of angulation. Fractures and angulations should be identified by anteroposterior and lateral radiographs. The aim of this study was to follow the healing after closed reduction of fifth metacarpal neck fractures in a pediatric population using the QuickDASH score to determine whether it results in clinically significant improvement. SUBJECTS AND METHODS: Between 2020 and 2022, our clinical record database for all metacarpal fractures treated at our institution was searched retrospectively every month. Children aged 18 years and younger with fifth metacarpal neck fractures treated with closed reduction and immobilization in our tertiary care emergency clinic were retrospectively reviewed. RESULTS: 52 pediatric patients were included in the study. The mean age at the time of injury was 14.04 years (SD=2.10, range=10-18 years). 92.30% (n=48) of the patients were male, and 7.70% (n=4) were female. CONCLUSIONS: Accurate diagnosis and appropriate treatment are crucial in the management of childhood fifth metacarpal fractures to ensure proper healing, prevent long-term complications, and facilitate optimal functional recovery.

Early Return of Motion in Patients With Intramedullary Screw Placement for Metacarpal and Phalangeal Fracture Fixation.

INTRODUCTION: Hand fractures are associated with significant morbidity. Current management standards often result in prolonged immobilization, stiffness, and delayed return to functional use. Intramedullary (IM) compression screws offer minimal soft tissue disruption and early postoperative active motion. In this study, we describe our outcomes after intraosseous fracture fixation using IM cannulated headless screws for a multitude of fracture patterns. METHODS: This study is a retrospective review of patients who underwent IM screw placement for fixation of metacarpal and phalangeal fractures by a single surgeon from 2017 to 2022. Data were collected to include patient demographics, fracture details, postoperative complications, and follow-up. Time to range of motion and return to unrestricted motion was recorded. RESULTS: There were 69 patients with 92 fractures (n = 54 metacarpal, n = 38 phalanx). The median patient age was 45 years (range, 18-89 years) with 75.4% males. Majority presented with a single fracture (n = 50, 72.5%), and 38 patients (55.1%) had open fractures. Small finger was the most affected digit (n = 35, 37.6%). The median time to allow range of motion from surgery was 8.7 days (interquartile range, 0-32) with 32 days (interquartile range, 10-62) for unrestricted use of the hand. Thirty-five patients (50.7%) were allowed controlled motion from the first postoperative day. One patient had loss of reduction requiring reintervention for hardware removal, and 1 patient had superficial skin infection managed with oral antibiotics. CONCLUSIONS: Our findings indicate that the IM screw provides reliable fixation for a wide variety of fracture patterns with a low complication rate and offers early return to functional use.

Clinical analysis of 1301 children with hand and foot fractures and growth plate injuries.

BACKGROUND: Fractures of hands and feet are common in children, but relevant epidemiological studies are currently lacking. We aim to study the epidemiological characteristics of hand and foot fractures and growth plate injuries in children and provide a theoretical basis for their prevention, diagnosis, and treatment. METHODS: We retrospectively analyzed the data of children with hand and foot fractures who were hospitalized at Shenzhen Children's Hospital between July 2015 and December 2020. Data on demographic characteristics, fracture site, treatment method, etiology of injury, and accompanying injuries were collected. The children were divided into four age groups: infants, preschool children, school children, and adolescents. The fracture sites were classified as first-level (the first-fifth finger/toe, metacarpal, metatarsal, carpal, and tarsal) and second-level (the first-fifth: proximal phalanx, middle phalanx, distal phalanx, metacarpal, and metatarsal) sites. The changing trends in fracture locations and injury causes among children in each age group were analyzed. RESULTS: Overall, 1301 children (1561 fractures; 835 boys and 466 girls) were included. The largest number of fractures occurred in preschool children (n = 549, 42.20%), with the distal phalanx of the third finger being the most common site (n = 73, 15.57%). The number of fractures in adolescents was the lowest (n = 158, 12.14%), and the most common fracture site was the proximal phalanx of the fifth finger (n = 45, 29.61%). Of the 1561 fractures, 1143 occurred in the hands and 418 in the feet. The most and least common first-level fracture sites among hand fractures were the fifth (n = 300, 26.25%) and first (n = 138, 12.07%) fingers, respectively. The most and least common first-level foot fracture locations were the first (n = 83, 19.86%) and fourth (n = 26, 6.22%) toes, respectively. The most common first-level and second level etiologies were life related injuries (n = 1128, 86.70%) and clipping injuries (n = 428, 32.90%), respectively. The incidence of sports injuries gradually increased with age, accounting for the highest proportion in adolescents (26.58%). Hand and foot fractures had many accompanying injuries, with the top three being nail bed injuries (570 cases, 36.52%), growth plate injuries (296 cases, 18.96%), and distal severed fracture (167 cases, 10.70%). Among the 296 growth plate injuries, 246 occurred on the hands and 50 on the feet. CONCLUSIONS: In contrast to previous epidemiological studies on pediatric hand and foot fractures, we mapped the locations of these fractures, including proximal, shaft, distal, and epiphyseal plate injuries. We analyzed the changing trends in fracture sites and injury etiologies with age. Hand and foot fractures have many accompanying injuries that require attention during diagnosis and treatment. Doctors should formulate accident protection measures for children of different ages, strengthen safety education, and reduce the occurrence of accidental injuries.

Metacarpal Small Incision for Carpal Tunnel Syndrome.

Endoscopic carpal tunnel release (ECTR) techniques have been established as a successful treatment for carpal tunnel syndrome and have proven equally effective as traditional open carpal tunnel release (OCTR) techniques in relieving pain and numbness. However, patients who undergo OCTR are more likely to experience scar tenderness and pillar pain and take longer to return to work. We present here a method of metacarpal small incision for carpal tunnel release (MSICTR) as a safe, reliable, cost-effective alternative surgical decompression of the median nerve of the wrist. This technique utilizes a metacarpal small incision and direct visualization of the median nerve and carpal tunnel contents, reducing the risk of permanent injury and neurasthenia when compared to traditional OCTR. MSICTR is also suitable for the examination of the median nerve, surrounding tendon sheath, or space-occupying lesions. MSICTR is associated with shorter operation times, less postoperative pain, faster recovery, and improved cosmetic results when compared to traditional OCTR. Therefore, MSICTR is an effective surgical decompression of the median nerve for the treatment of carpal tunnel syndrome.

Equine skeletal scintigraphy: Comparing lesion detection ability of methylene diphosphonate and hydroxymethylene diphosphonate in the caudal cervical and proximal metacarpal/metatarsal regions.

BACKGROUND: Data regarding the lesion detection ability of different radiotracers are lacking in equine bone scintigraphy. METHODS: In this prospective study, hydroxymethylene diphosphonate (HMDP) and methylene diphosphonate (MDP) were compared in horses with increased radiopharmaceutical uptake either in the caudal cervical region (CS group) or in the proximal metacarpal/metatarsal region (PMR group). Region of interest analysis was used to determine normal bone-to-soft tissue ratios, lesion-to-normal bone ratios and lesion-to-soft tissue ratios. Qualitative scoring and total count rates were recorded for each image. RESULTS: A total of 213 scintigrams were included. Within the PMR group, there were significantly higher lesion-to-normal bone ratios for MDP compared with HMDP (p = 0.02). In the CS group, normal bone-to-soft tissue ratios were significantly higher for HMDP (p = 0.01). The interobserver agreement with regard to the qualitative assessment of the scintigrams was poor. LIMITATION: Paired studies, comparing the different radiotracers in the same patient, were not feasible. CONCLUSION: This study revealed minor differences between the two radiotracers, although these have no practical implications. Both radiopharmaceuticals are well suited for detecting lesions at the investigated sites using equine bone scintigraphy.

Morphological and radiographic studies on the Manus region in the Arabian one-humped camel (Camelus dromedaries).

The study aims to analyse the normal anatomical and radiographical features of the Manus of the southern Aswanian-adapted Arabian one-humped camel, providing crucial data for diagnosing and treating various ailments. Our study was applied to 10 cadaver forelimbs of adult male one-humped camels (4-5 years old) for an explanation of the gross anatomy of the bones of the Manus region from under the carpal bones by using traditional techniques, including the gross anatomical, radiographic and x-ray (at the dorsopalmar and lateral planes) of the preparation of Manus bones. Our results showed that the large fused (third and fourth) metacarpal bones, in which the fusion extended along the entire length of the bone except at the distal end, diverged to form separate articulations with cross-ponding digits. As described in all ruminant species, especially the camel, there were two digits, and each digit consisted of three phalanges and two proximal sesamoid bones. Our radiographic x-ray data revealed that the complete radiopaque septum that completely divided the medullary cavity into two separate parts was clear from the dorsopalmar view, while the lateral view showed the proximal sesamoid bones that were placed over each other and located palmar to the head of the large metacarpal bone. In conclusion, our study reveals the adaptations of the Arabian one-humped camel to Egyptian conditions, aiding in the early diagnosis of lameness and digit problems and enabling veterinarians and camel owners to better address these issues, thereby improving the overall health and well-being of these animals.

Influence of microarchitecture on stressed volume and mechanical fatigue behaviour of equine subchondral bone.

Fractures of the equine metacarpophalangeal (MCP) joint are among the most common and fatal injuries experienced by racehorses. These bone injuries are a direct result of repetitive, high intensity loading of the skeleton during racing and training and there is consensus that they represent a mechanical fatigue phenomenon. Existing work has found the fatigue life of bone to be strongly determined by bone microarchitecture and the resulting stressed volume (i.e., the volume of bone stressed above assumed yield). The purpose of this study was to quantify the influence of bone microarchitecture on the mechanical fatigue behaviour of equine subchondral bone from the MCP joint across a wide variety of sample types. Forty-eight subchondral bone samples were prepared from the third metacarpal (MC3) and proximal phalanx (P1) of 8 horses and subsequently imaged using high resolution micro-computed tomography (µCT) to quantify microarchitectural features of interest, including bone volume fraction, tissue mineral density, pore size, pore spacing, and pore number. Samples were cyclically loaded in compression to a stress of 70 MPa, and fatigue life was defined as the number of cycles until failure. Finite element models were created from the µCT images and used to quantify stressed volume. Based on the expected log point-wise predictive density, stressed volume was a strong predictor of fatigue life in both the MC3 and P1. A regional analysis indicated fatigue life was more strongly associated with bone volume fraction in the superficial (r2 = 0.32, p < 0.001) and middle (r2 = 0.70, p < 0.001) regions of the subchondral bone, indicating the prominent role that the cortical plate played in the fatigue resistance of equine subchondral bone. By improving our understanding of the variance in fatigue life measurements, this research helps clarify the underlying mechanisms of the mechanical fatigue process and provides a basic understanding of subchondral bone injuries in the equine fetlock joint.

The first dorsal metacarpal artery flaps versus reverse homodigital dorsal flaps for thumb reconstruction: a systematic review and meta-analysis.

PURPOSE: This review was performed to systematically compare the effectiveness and safety of the first dorsal metacarpal artery flaps (FDMAF) and reverse homodigital dorsal flaps (RHDF) for thumb reconstruction. METHODS: All literatures, which compared FDMAF versus RHDF for thumb reconstruction, were acquired through a comprehensive search in multiple databases from inception until 31st August 2022. A meta-analysis was performed using the Cochrane Collaboration's RevMan 5.4 software. RESULTS: A total of 19 articles were retrieved, comprising 396 patients in the FDMAF group and 423 patients in the RHDF group. The pooled estimates suggested that there were no significant differences in venous congestion, complications about flap necrosis and reduced range of motion (ROM) of thumb, static 2-point discrimination (S-2PD) between the two groups. On the other hand, patients in the RHDF group had less vascular crisis (odds ratio [OR] = 3.15, 95%CI, 1.31-7.56), complications about poor cortical reorientation (OR = 440.02, 95%CI, 91.97-2105.27) and higher satisfaction rate (OR = 0.56, 95% CI, 0.33-0.96) than those in the FDMAF group. CONCLUSIONS: The two surgical procedures were both safe and reliable since no significant differences were found in flap necrosis between the two groups. However, the patients in the RHDF group had less complications about vascular crisis, poor cortical reorientation and higher satisfaction rate. Accordingly, we thought RHDF may be more superior for thumb reconstruction than FDMAF.

Mechanical response of local regions of subchondral bone under physiological loading conditions.

Most fractures in the third metacarpal bone of equine athletes occur due to repeated cycles of high load magnitudes and are commonly generated during fast-training workouts. These repetitive loads may induce changes in the microstructure and mechanical properties that can develop into subchondral bone (SCB) injuries near the articular surface. In this study, we investigated the fatigue behaviour of local regions in SCB (near the articular surface i.e., 2 mm superficial SCB and the underlying 2 mm deeper SCB) under a simulated fast-training workout of an equine athlete. A fatigue test on SCB specimens was designed to simulate the fast-training workout, which comprised of repeated load cycles with varying load magnitude, representing the varying gait speed during a fast-training workout. The fatigue test was applied three times to each of the five cylindrical SCB specimens harvested from the left and right metacarpal condyles of five thoroughbred racehorses). All specimens completed at least one fatigue test. Three specimens completed all three fatigue tests with no visible cracks identified with Micro-CT scans. The other two specimens failed in the second fatigue test, and cracks were identified with Micro-CT scans in the various local regions. Using Digital Image Correlation (DIC) analysis, we found that in the local regions of all specimens, modulus decreased between load cycles corresponding to 68 and 93 MPa load magnitudes (equivalent to the fastest gallop speed). Wherein specimens that failed exhibited a greater decrease in modulus (in superficial SCB by 45.64 ± 5.66% and in deeper SCB by -36.85 ± 10.47% (n = 2)) than those not failed (in superficial SCB by -7.45 ± 14.62% and in deeper SCB by -5.67 ± 7.32% (n = 3)). This has provided evidence that the loads on SCB at galloping speeds are most likely to produce fatigue damage and that the damage induced is localised. Furthermore, one of the failed specimens exhibited a peak in the tensile strain rather than compressive strain in the superficial region with a rapid decrease in modulus. In addition, the superficial region of all specimens exhibited greater residual tensile strain than that of the deeper region.

Novel Mini-Invasive Surgical Technique for Treating Fifth Metacarpal Neck Fractures: A Case Report.

BACKGROUND Fracture of the fifth metacarpal of the hand is due to trauma to the clenched fist. The non-displaced fracture can be treated by splinting and immobilization, but fracture dislocation requires individualized management to ensure the return of function. The Jahss maneuver for reduction of volar displaced metacarpal neck fractures involves flexion of the metacarpophalangeal and proximal interphalangeal joint at 90°, with the proximal phalanx used to reduce the metacarpal head. This report is of a 25-year-old male Italian pianist with a displaced fifth metacarpal neck fracture successfully treated by reduction using the Jahss maneuver and K-wire attachment of subchondral bone to the metacarpal. CASE REPORT A pianist presented with a trauma to his right hand due to punching a wall. Radiograph images demonstrated an angulated, displaced right fifth neck fracture. A specific approach was decided, considering the complexity of the musical movements and the patient's performance needs. After fracture's reduction by the Jahss maneuver, 2 retrograde cross-pinning K-wires were inserted at the subchondral bone of the metacarpal head. Healing under splinting was uneventful, and the K-wires were removed after 45 days. At 4 months after surgery, the patient had complete recovery of both range of motion and strength. CONCLUSIONS Our technique avoided piercing the metacarpophalangeal joint capsule, preventing extensor tendon damage, dislocation, instability, and pain and retraction of the extensor cuff. This novel mini-invasive technique successfully achieved early metacarpophalangeal joint motion, joint stability, and complete recovery of movements in all planes.

The deep trabecular structure of first metacarpals in extant hominids.

OBJECTIVES: Recent studies have associated subarticular trabecular bone distribution in the extant hominid first metacarpal (Mc1) with observed thumb use, to infer fossil hominin thumb use. Here, we analyze the entire Mc1 to test for interspecific differences in: (1) the absolute volume of trabecular volume fraction, (2) the distribution of the deeper trabecular network, and (3) the distribution of trabeculae in the medullary cavity, especially beneath the Mc1 disto-radial flange. MATERIALS AND METHODS: Trabecular bone was imaged using micro-computed tomography in a sample of Homo sapiens (n = 11), Pan paniscus (n = 10), Pan troglodytes (n = 11), Gorilla gorilla (n = 10) and Pongo sp., (n = 7). Using Canonical Holistic Morphometric Analysis (cHMA), we tested for interspecific differences in the trabecular bone volume fraction (BV/TV) and its relative distribution (rBV/TV) throughout the Mc1, including within the head, medullary cavity, and base. RESULTS: P. paniscus had the highest, and H. sapiens the lowest, BV/TV relative to other species. rBV/TV distribution statistically distinguished the radial concentrations and lack of medullary trabecular bone in the H. sapiens Mc1 from all other hominids. H. sapiens and, to a lesser extent, G. gorilla also had a significantly higher trabecular volume beneath the disto-radial flange relative to other hominids. DISCUSSION: These results are consistent with differences in observed thumb use in these species and may also reflect systemic differences in bone volume fraction. The trabecular bone extension into the medullary cavity and concentrations beneath the disto-radial flange may represent crucial biomechanical signals that will aid in the inference of fossil hominin thumb use.

Reconstruction of finger contracture with an expanded first dorsal metacarpal artery perforator flap: A case report.

Volar finger contractures can be challenging for plastic surgeons. The dorsal metacarpal artery perforator (DMCAP) flap is frequently used to cover bones, tendons, and neurovascular structures in the dorsum of the hand after trauma and burns as an alternative to grafts and free flaps. We aimed to report volar finger defect reconstruction with expanded DMCAP flap. A 9-year-old male patient applied to our clinic with the complaint of inability to open the second finger of the left hand after an electrical burn that caused proximal and distal interphalangeal joints flexion contractures. Reconstruction was planned for the patient with a two-session expanded first DMCAP flap. A 16 mL 5 × 3 cm tissue expander was placed in the prepared area from the vertical incision in the first session. The tissue expander was inflated with 4 mL of isotonic solution. The DMCA area was enlarged 6 weeks later by giving 22 mL of isotonic solution. After the pedicle dissection, the 9 × 3 cm DMCAP flap was elevated by dissection over the paratenon. With 180° of rotation, the left-hand second finger was adapted to the 6 × 2 cm defect area on the volar face. The flap donor site was closed primarily. The operation was terminated by placing the hand on a protective splint. There were no complications in the flap in the postoperative 6 months. The patient was referred to the physical therapy and rehabilitation department. As a result, an expanded DMCAP flap may cover volar tissue defects up to the distal phalanx. This report may present the first case in which volar finger contracture reconstruction was performed with an expanded first DMCAP flap after an electrical burn in a pediatric patient.

Morphological integration and shape covariation between the trapezium and first metacarpal among extant hominids.

OBJECTIVES: The shape of the trapezium and first metacarpal (Mc1) markedly influence thumb mobility, strength, and the manual abilities of extant hominids. Previous research has typically focused solely on trapezium-Mc1 joint shape. Here we investigate how morphological integration and shape covariation between the entire trapezium (articular and non-articular surfaces) and the entire Mc1 reflect known differences in thumb use in extant hominids. MATERIALS AND METHODS: We analyzed shape covariation in associated trapezia and Mc1s across a large, diverse sample of Homo sapiens (n = 40 individuals) and other extant hominids (Pan troglodytes, n = 16; Pan paniscus, n = 13; Gorilla gorilla gorilla, n = 27; Gorilla beringei, n = 6; Pongo pygmaeus, n = 14; Pongo abelii, n = 9) using a 3D geometric morphometric approach. We tested for interspecific significant differences in degree of morphological integration and patterns of shape covariation between the entire trapezium and Mc1, as well as within the trapezium-Mc1 joint specifically. RESULTS: Significant morphological integration was only found in the trapezium-Mc1 joint of H. sapiens and G. g. gorilla. Each genus showed a specific pattern of shape covariation between the entire trapezium and Mc1 that was consistent with different intercarpal and carpometacarpal joint postures. DISCUSSION: Our results are consistent with known differences in habitual thumb use, including a more abducted thumb during forceful precision grips in H. sapiens and a more adducted thumb in other hominids used for diverse grips. These results will help to infer thumb use in fossil hominins.

Intramedullary Fixation of Hand Fractures and Arthrodeses.

Intramedullary fixation has long been popular for fracture fixation in the upper extremity from the shoulder through the carpus. Recently, intramedullary fixation in the hand has gained increasing interest, specifically in the metacarpals and phalanges, corresponding with the development of improved cannulated headless screw technology. Along with the advantages of increased operative speed and less surgical dissection, which can promote rapid healing, many benefits exist, supporting their use despite some drawbacks. This article reviews the background and biomechanics of intramedullary fixation with a specific focus on cannulated headless screws, describes the application and techniques of intramedullary screw fixation in the hand, and details the associated outcomes and costs for metacarpal fractures, phalangeal fractures, and interphalangeal joint arthrodesis.

Positron emission tomography assessment of metacarpal/metatarsal condylar fractures post surgical repair: Prospective study in 14 racehorses.

OBJECTIVES: To assess 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings associated with metacarpal/metatarsal condylar fractures at the time of fracture repair and through healing. STUDY DESIGN: Prospective descriptive study. ANIMALS: Fourteen Thoroughbred racehorses. METHODS: 18F-NaF PET was performed within 4 days of surgical metacarpal/metatarsal condylar fracture repair, on both the injured and contralateral limb. Follow-up PET scans were offered at 3- and 5-months post fracture repair. Areas of abnormal uptake were assessed using a previously validated grading system. RESULTS: Eight fractures were located in the parasagittal groove (PSG) (six lateral and two medial) and six fractures were located abaxial to the PSG (non-PSG) through the palmar/plantar condyle (all lateral). All horses in the latter group had uptake in the lateral palmar condyle of the contralateral limb suggestive of stress remodeling. Three horses with PSG fractures had uptake in a similar location in the contralateral limb. Horses with lateral condylar fracture only presented minimal or mild uptake in the medial condyle, which is considered atypical in the front limbs for horses in full training. Four horses developed periarticular uptake in the postoperative period suggestive of degenerative joint disease, three of these horses had persistent uptake at the fracture site. These four horses did not return to racing successfully. CONCLUSION: The findings of this study provide evidence of pre-existing lesions and specific uptake patterns in racehorses suffering from metacarpal/metatarsal condylar fractures. CLINICAL SIGNIFICANCE: PET has a possible role in the prevention, diagnosis, and postoperative monitoring of metacarpal/metatarsal condylar fractures in racehorses.

Basal osteotomy of the first metacarpal using patient-specific guides and instrumentation: biomechanical and 3D CT-based analysis.

INTRODUCTION: The aim of this study was to investigate the radiological outcomes of proximal closing metacarpal extension osteotomies using patient-specific guides and instruments (PSI) in early-stage trapeziometacarpal osteoarthritis to gain further insight into the joint loading surface and the benefits of the procedure. METHODS: In a prospective observational study, nine patients were included between 11/2020 and 12/2021, undergoing a total of ten proximal metacarpal extension osteotomies for basal thumb osteoarthritis. Computer-assisted surgical planning was performed using computed tomography (CT) and three-dimensional (3D) segmentation, allowing the fabrication of 3D-printed PSIs for surgical treatment. Inclusion criteria were a 1-year follow-up by CT to assess postoperative correction of the positional shift of the first metacarpal (MC1) and the location of peak loads compared with the preoperative situation. RESULTS: Radiographic analysis of the peak loading zone revealed a mean displacement on the articular surface of the trapezius of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to palmar, and on the articular surface of the MC1 of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to dorsal. CONCLUSION: There were trends indicating that a flatter pressure distribution and a dorsal shift of the peak loading zone may contribute to an improvement in subjective pain and patient satisfaction associated with this surgical procedure. The non-significant radiological results and the minor dorsal-radial shifts in our small study group limit a firm conclusion. LEVEL OF EVIDENCE: III.

The stacking concept: cannulated screws for extra-articular metacarpal base fracture of the thumb.

An alternative technique to treat extra-articular fractures of the base of the first metacarpal with intramedullary canulated headless screws is presented. The principle is creating an internal fixator within the medullary canal by introducing multiple retrograde screws until they have jammed.

An alternative method to reconstruct grade-3 hypoplastic thumb by hemi-metacarpal transfer.

We designed a new method using hemi-longitudinal second metacarpal bone to reconstruct grade-3 hypoplastic thumbs. Seven patients were treated in two stages. In the first stage, the second metacarpal was split longitudinally and transferred to reconstruct the first metacarpal. In the second stage, opponensplasty was performed by transferring the FDS tendon. Bone union was achieved in all cases. All patients could oppose to their middle finger at least. They managed to do daily activities such as writing, eating, using smartphones and so on. This is a useful procedure to preserve a 5-digit hand with good function in treating grade-3 hypoplastic thumbs, with no harm to the foot and no need for vascular anastomosis. LEVEL OF EVIDENCE: IV.

Variation and covariation of external shape and cross-sectional geometry in the human metacarpus.

OBJECTIVES: Analyses of external bone shape using geometric morphometrics (GM) and cross-sectional geometry (CSG) are frequently employed to investigate bone structural variation and reconstruct activity in the past. However, the association between these methods has not been thoroughly investigated. Here, we analyze whole bone shape and CSG variation of metacarpals 1-5 and test covariation between them. MATERIALS AND METHODS: We analyzed external metacarpal shape using GM and CSG of the diaphysis at three locations in metacarpals 1-5. The study sample includes three modern human groups: crew from the shipwrecked Mary Rose (n = 35 metacarpals), a Pre-industrial group (n = 50), and a Post-industrial group (n = 31). We tested group differences in metacarpal shape and CSG, as well as correlations between these two aspects of metacarpal bone structure. RESULTS: GM analysis demonstrated metacarpus external shape variation is predominately related to changes in diaphyseal width and articular surface size. Differences in external shape were found between the non-pollical metacarpals of the Mary Rose and Pre-industrial groups and between the third metacarpals of the Pre- and Post-industrial groups. CSG results suggest the Mary Rose and Post-industrial groups have stronger metacarpals than the Pre-industrial group. Correlating CSG and external shape showed significant relationships between increasing external robusticity and biomechanical strength across non-pollical metacarpals (r: 0.815-0.535; p ≤ 0.05). DISCUSSION: Differences in metacarpal cortical structure and external shape between human groups suggest differences in the type and frequency of manual activities. Combining these results with studies of entheses and kinematics of the hand will improve reconstructions of manual behavior in the past.