Three-dimensional analysis of the ligamentous attachments of the second through fifth carpometacarpal joints

Bennett fracture combined with hamate fracture: carpometacarpal joint 'diagonal' fracture and dislocation: a case report

BACKGROUND

Multiple carpometacarpal fractures and dislocations are rare. This case report describes a novel multiple carpometacarpal injury, namely, 'diagonal' carpometacarpal joint fracture and dislocation.

CASE PRESENTATION

A 39-year-old male general worker sustained a compression injury to his right hand in the dorsiflexion position. Radiography indicated a Bennett fracture, hamate fracture, and fracture at the base of the second metacarpal. Subsequent computed tomography and intraoperative examination confirmed an injury to the first to fourth carpometacarpal joint along a diagonal line. The normal anatomy of the patient's hand was successfully restored via open reduction combined with Kirschner wire and steel plate fixation.

CONCLUSION

Our findings highlight the importance of taking the injury mechanism into account to avoid a missed diagnosis and to choose the best treatment approach. This is the first case of 'diagonal' carpometacarpal joint fracture and dislocation to be reported in the literature.

Hamate's coronal fracture: diagnostic and therapeutic approaches based on a long-term follow-up

Hamate fractures are commonly divided into hook fractures and body fractures. The coronal fractures as a special form of hamate’s body fracture are very rare injuries. Because of unspecific clinical findings and the mostly inconclusive x-ray imaging, these fractures are frequently overseen or misdiagnosed. This leads to further complications like secondary arthritis, persisting pain, and functional deficits in patient’s wrist mobility. In our study, a collocation of coronal hamate fractures is analyzed and evaluated with respect to functional outcome after operative treatment and compared to the literature. Furthermore, we compare the strategies for diagnosis and treatment in our clinical center with those presented in the literature.

Our standard in the initial diagnostic process is to obtain radiographs in an anterior-posterior, lateral, and 30° oblique view of the wrist. For further diagnosis and preoperative planning, a CT scan of the wrist is obligatory. Due to the high occurrence of comorbidities (especially CMC dislocations) all patients in our cohort obtained operative treatment.

In long-term post-operative evaluation, we present the following results:

The Manchester-Modified Disability of the Shoulder, Arm and Hand Score (M² DASH) imposed with an average of 26.22 points (MD=22/ SD=11.31/MIN=18/MAX=52). None of the re-evaluated patients sorrowed for severe pain in rest. Four patients stated pain (ranging from 3 to 5 on numeric analogue scale) after heavy burden (e.g. boxing, weight lifting). In exploring the range of motion of the operated hand the following results are obtained: dorsal extension: average 83.33° (MD=85°/SD=3.54°/MIN=75°/MAX=85°), flexion: average 77.78° (MD=80°/SD=4.41°/MIN=70°/MAX=80°). Additionally, a performance testing was conducted: fist clenching sign: complete without pain in 100%, pinch grip: complete in 77.78%, opposition digitus manus I–V complete in 66.67%.

The conservative treatment is not recommended (especially shown in the here presented “add” case with a misdiagnosed fracture). The open approach has its advantages compared to a closed operative procedure and should always be intraoperatively considered as an operative expansion.

Augmented External Fixation of Ulnar Carpometacarpal Joint Fracture Dislocations

Ulnar-sided carpometacarpal (CMC) joint fracture dislocations are relatively uncommon, frequently associated with fractures of the metacarpal base and/or hamate, and often sustained by young male individuals secondary to striking a hard object. The complexity of ulnar-sided CMC fracture dislocations necessitates careful restitution of anatomic alignment and joint congruency for mobility and stability. Miniaturization of the external fixation device has allowed application to the hand. Spanning external fixation utilizes the principles of "ligamentotaxis"-indirect reduction through distraction forces of capsule-ligamentous structures. Treatment options for ulnar-sided CMC fracture dislocations are varied. Our surgical technique involving an external fixation device is reviewed. Clinical and chart review was performed on the last 10 patients undergoing acute surgical repair of ulnar-sided CMC fracture dislocations with intra-articular comminution by the senior author. Surgical technique used percutaneous Kirschner wire fixation and a spanning, miniature, external fixation device. Minimal follow-up was 1 year. Radiographs from the most recent appointment were evaluated by 2 independent reviewers. Patients rated their level of pain and assessed function using a subjective outcome instrument. Mean total active motion, when comparing traumatized digit to same digit in contralateral hand, was 100%. All fractures healed primarily with maintenance of congruent joint space and without radiographic displacement or arthrosis. Patient satisfaction was high and all patients returned to preinjury level of function. Our study demonstrates the use of an external fixation device in the management of ulnar-sided CMC fracture dislocations to be effective in reestablishing and maintaining normal hand anatomy, reducing pain, increasing function, and preserving motion.

Development of a biomechanical model of the wrist joint for patient-specific model guided surgical therapy planning: Part 1

An enhanced musculoskeletal biomechanical model of the wrist joint is presented in this article. The developed computational model features the two forearm bones radius and ulna, the eight wrist bones, the five metacarpal bones, and a soft tissue apparatus. Validation of the model was based on information taken from the literature as well as own experimental passive in vitro motion analysis of eight cadaver specimens. The computational model is based on the multi-body simulation software AnyBody. A comprehensive ligamentous apparatus was implemented allowing the investigation of ligament function. The model can easily patient specific personalized on the basis of image information. The model enables simulation of individual wrist motion and predicts trends correctly in the case of changing kinematics. Therefore, patient-specific multi-body simulation models are potentially valuable tools for surgeons in pre- and intraoperative planning of implant placement and orientation.

Reliability of classification of ring and little finger carpometacarpal joint fracture subluxations: a comparison between two-dimensional computed tomography and three-dimensional computed tomography classifications

The aims of this study were to develop a classification for ring and little finger carpometacarpal joint fracture subluxations based on three-dimensional computed tomography images and evaluate the inter- and intraobserver reliability of the three-dimensional computed tomography classification. A retrospective review was performed of 30 cases of ring and little finger carpometacarpal joint fracture subluxations from 2005 to 2013. We classified ring and little finger carpometacarpal joint fracture subluxations into three types based on three-dimensional computed tomography images. An orthopaedic surgeon with 2 years of experience, a consultant hand surgeon with 8 years of experience, and a consultant radiologist with 9 years of experience, who were completely blind to the treatment algorithm, evaluated 30 cases twice at a 2-week interval using our new classification based on three-dimensional computed tomography images and the other classification based on two-dimensional computed tomography images. Our three-dimensional computed tomography classification showed almost perfect interobserver and intraobserver reliability and resulted in a better level of agreement than two-dimensional computed tomography classification.

A finite element analysis of two novel screw designs for scaphoid waist fractures

The scaphoid is the most often fractured carpal bone. Scaphoid fracture repair with a headless compression screw allows for early functional recovery. The rotational stability of a single screw may be limited, having a potential negative impact on the healing process. Two novel screws have been designed to provide improved rotational stability compared to the existing ones. Using a computational finite element model of a scaphoid osteotomy, we compared the efficacy of one simple screw and the two new screws in restricting inter-fragmentary motion (IFM) in three functional positions of the wrist and as a function of inter-fragmentary compression force. The in-plane IFM was primary rotational and was better restricted by the new screws compared to the conventional one when the inter-fragmentary compression force was below 15-20 N, but provided no clear benefit in total flexion independently of the compression force. To better understand the differences in the non-compressed case, we analyzed the acting moments and investigated the effects of the bending and torsional screw stiffness on IFM. By efficiently restricting the inter-fragmentary shear, the new screws may be clinically advantageous when the inter-fragmentary compression force is partially or completely lost and may provide further benefits toward earlier and better healing of transverse waist fractures of the scaphoid.

Three-dimensional Analysis of the Attachment and Path of the Transverse Carpal Ligament

PURPOSE

The purpose of this study was to describe and evaluate the detailed anatomic locations and areas of ligamentous attachments and paths of the transverse carpal ligament (TCL) on a three-dimensional (3-D) surface model.

METHODS

Ten fresh-frozen cadaver wrists were used to dissect and identify the TCL. Their ligament attachments and whole bone surfaces were digitized three-dimensionally and their areas evaluated. The attachments of each ligament were represented in a model combining CT surfaces overlaid by a digitized 3-D surface, and were also visually depicted with a different color for each on 3-D images of the bones.

RESULTS

The TCL was found to be composed of two or three discrete ligaments. Both the trapezium-hook of hamate ligament and the trapezium-pisiform ligament were identified in all ten specimens. The scaphoid-pisiform ligament was found in only two of the ten specimens. The average areas of the attachments of the TCL were 42.7 mm(2) on the trapezium, 30.0 mm(2) on the hook of hamate, 21.6 mm(2) on the pisiform, and 12.7 mm(2) on the scaphoid.

CONCLUSIONS

The anatomic 3-D attachment sites of the TCL were visually shown qualitatively, and their areas quantified. This 3-D information offers further knowledge and understanding of the anatomy and biomechanics of the TCL. It could also help in the accurate assessment of radiographic images and treatment of various wrist injuries and diseases when performing such procedures as carpal tunnel release, Guyon's canal release, trapeziectomy, hook of hamate excision, or arthroscopy.

An attachment-based description of the medial collateral and spring ligament complexes

BACKGROUND

Anatomy of the medial collateral and spring ligament complexes has been the cause of confusion. The anatomic description is highly dependent on the source studied and little agreement exists between texts. In addition, inconsistent nomenclature has been used to describe the components. This study attempted to clarify confusion through the creation of a 3D ligament map using attachment-based dissection.

METHODS

Nine fresh foot and ankle specimens were observed. The medial collateral ligament and spring ligament complexes were dissected using their attachment sites as a guide to define individual components. Each component's perimeter and thickness was measured and each bony attachment was mapped using a microscribe 3D digitizer.

RESULTS

Five components were identified contributing to the ligament complexes of interest: the tibiocalcaneonavicular, superficial posterior tibiotalar, deep posterior tibiotalar, deep anterior tibiotalar, and inferoplantar longitudinal ligaments. The largest component by total attachment area was the tibiocalcaneonavicular ligament followed by the deep posterior tibiotalar ligament. The largest ligament surface area of attachment to the tibia and talus was the deep posterior tibiotalar ligament. The largest attachment to the navicular and calcaneus was the tibiocalcaneonavicular ligament, which appeared to function in holding these bones in proximity while supporting the head of the talus.

CONCLUSION

By defining complex components by their attachment sites, a novel, more functional and reproducible description of the medial collateral and spring ligament complexes was created.

CLINICAL RELEVANCE

The linear measurements and 3D maps may prove useful when attempting more anatomically accurate reconstructions.

Biomechanical comparison of the hand-based transplant used in bone-tissue-bone scapho-lunate ligament reconstruction

Although work has been published comparing the five most commonly used transplant techniques to the properties of the scapho-lunate interosseous ligament (SLIL), no study has been carried out which compares the biomechanical properties of the different bone-tissue-bone autografts to each other, using a standard methodology of testing. The hypothesis of this study was that mechanically significant differences in the material properties of commonly used bone-tissue-bone exist when compared to each other. We tested the dorsal part of the SLIL and the five most quoted transplants in the literature: capitate to trapezoid; trapezoid to second metacarpal; third metacarpal-carpal; dorsal capitate-hamate; 4-5 extensor retinaculum. For each transplant, we measured failure load, failure displacement, width, and thickness. Anova was used to compare the different results obtained and the level of significance attributed to P<0.05. Load to failure were: SLIL 94.3±42.86N; capitate to trapezoid 37.7±23.13N; trapezoid to second metacarpal 45.43±14.28N; third metacarpal-carpal 60.11±19.94N; dorsal capitate-hamate 63±25.51N; 4-5 retinaculum 15.67±10.7N. Only the dorsal capitate-hamate ligament showed to have no significant (P>0.05) difference in term of load to failure, all the others was significantly weaker (P<0.05). Previous biomechanical studies have identified the dorsal region of the SLIL as the most structurally and functionally important area of the SLIL. As a result, attention has been more specifically brought to the replacement of the dorsal portion of the SLIL. An attempt to achieve a reconstruction that reproduces more closely the SLIL has generated research on the use of bone-tissue-bone composite graft, several donor sites have been used in order to find the most similar. Our results suggest that, using a normalized method to compare the previously described grafts harvested at the wrist level, that the dorsal capitate-hamate ligament has the closest properties to the native dorsal scapho-lunate ligament.

MRI of the wrist in juvenile idiopathic arthritis: erosions or normal variants? A prospective case-control study

BACKGROUND

Bony depressions at the wrist resembling erosions are frequently seen on MRI in healthy children. The accuracy of MRI in detecting early bony destruction is therefore questionable. We compared findings on MRI of the wrist in healthy children and those with juvenile idiopathic arthritis (JIA) to investigate markers for true disease.

MATERIALS AND METHODS

We compared the number and localisation of bony depressions at the wrist in 85 healthy children and 68 children with JIA, ages 5-15 years. The size of the wrist was assessed from a radiograph of the wrist performed on the same day as the MRI.

RESULTS

No significant difference in the number of bony depressions in the carpal bones was seen between healthy children and children with JIA at any age. Depressions are found in similar locations in the two groups, except for a few sites, where bony depressions were seen exclusively in the JIA group, particularly at the CMC joints. The wrist was significantly smaller in children with JIA (P < 0.001).

CONCLUSIONS

Using adult scoring systems and standard MR sequences in the assessment of bone destruction in children may lead to overstaging or understaging of disease. At present, standard MRI sequences cannot easily be used for assessment of early signs of erosions in children.

Arthroplasty of the scaphoid-trapezium-trapezoid and carpometacarpal joints

Resection arthroplasty is an old, and yet reliable, solution for the isolated osteoarthritis (OA) of some joints of the hand. With complication low rates, this technically undemanding option is ideal for scapho-trapezial-trapezoidal joint OA, as well as for the OA of the carpometacarpal joints of the fingers. This paper reviews its indications, surgical technique, and results.

Quantitative 3D-CT anatomy of hamate osteoarticular autograft for reconstruction of the middle phalanx base

BACKGROUND

Hamate osteoarticular autografts are difficult to obtain and it is unclear to what degree the graft matches the joint surface to be replaced and whether a direct ulnar approach might provide a more reliable graft than the standard proximal to distal approach.

PURPOSE

We modeled hemihamate osteotomies using quantitative three-dimensional CT (3D-CT) to measure the amount of hamate articular surface used and the match with the native volar base of the middle phalanx.

METHODS

In virtual hemihamate osteotomies (standard and direct ulnar) on CTs of 20 patients (11 men and nine women), we measured the percentage of hamate articular surface used for each finger, the match of the articular contour, and the percentage of hamate articular surface removed.

RESULTS

The autograft in the standard approach used an average of 26% of the hamate articular surface and had an average 75% match of the articular contour with the volar half of the middle phalanx base. A direct ulnar approach removed an additional small margin of dorsal ulnar hamate with an average maximum width of 2.5 mm and volume of 27 mm(3).

CONCLUSIONS

An osteoarticular allograft from the hamate to replace the volar half of the middle phalanx base uses less than 1/3 of the hamate articular surface even if the dorsal ulnar margin of the hamate is taken with the graft.

CLINICAL RELEVANCE

These data suggest that it might be feasible to make the deep cut from a direct ulnar approach.

The use of a third metacarpal base osteoarticular flap for treatment of metacarpophalangeal joint traumatic defects

PURPOSE

To describe the use of a pedicled osteoarticular flap harvested from the base of the third metacarpal for the treatment of traumatic defects of the metacarpophalangeal (MCP) joints.

METHODS

From February 2006 to January 2008, we included in the study 15 patients with posttraumatic defects of the MCP joints. The mean age of the patients was 35 years. The injured MCP joints were located in the thumb (n = 6) and index (n = 4), middle (n = 4), and ring fingers (n = 1). Of the 15 patients, 10 presented with acute injuries and 5 with old injuries. At follow-up, we assessed active motion and pinch strength and compared all measurements with those from the opposite hand. In patients with old MCP joint injuries, we also compared preoperative and postoperative motion and pinch strength. We assessed hand function using the Disabilities of the Arm, Shoulder, and Hand questionnaire.

RESULTS

At the final follow-up (mean, 28 mo), the mean motion arc of the reconstructed MCP joints and the opposite joints was 46° and 91°, respectively, and the mean pinch strength of the injured and opposite sides was 5.4 and 7.1 kg, respectively. For the 5 patients with old injuries to the fingers, the mean preoperative and postoperative motion arc was 2° and 43°, and the mean preoperative and postoperative pinch strength was 1.6 and 5.3 kg, respectively. The mean Disabilities of the Arm, Shoulder, and Hand score of the entire patient series was 9, whereas the mean preoperative and postoperative scores of the 5 patients with old injuries were 44 and 17, respectively.

CONCLUSIONS

The use of a pedicled osteoarticular flap harvested from the base of the third metacarpal is a reliable technique for the treatment of traumatic defects of the MCP joints.

Osteoarticular pedicle flap from the capitate to reconstruct traumatic defects in the head of the proximal phalanx

PURPOSE

To describe the reconstruction of traumatic defects in the head of the proximal phalanx using an osteoarticular pedicle flap from the capitate.

METHODS

From January 2004 to December 2007, we treated 15 patients with traumatic defects of the head of the proximal phalanx at our institution. All of these injuries involved 1 condyle of the proximal phalanx. There were 11 male and 4 female patients; the mean age was 32 years. The injuries occurred in the index (n = 6), middle (n = 7), and ring (n = 2) fingers. At the final follow-up, we assessed space narrowing of the proximal interphalangeal joint and flap necrosis using plain radiography. We measured active motion and pinch and grip strength of the hand and compared all measurements with those on the opposite side. Patients rated injured-joint pain and donor-joint pain using a visual analog scale. We assessed hand function using the Disabilities of the Arm, Shoulder, and Hand scale.

RESULTS

Patient follow-up averaged 52 months. At the final follow-up, we noted narrowing of the proximal interphalangeal joint in 3 cases, but we observed no flap necrosis. The mean active motion arc of the injured and opposite proximal interphalangeal joints was 50° and 96°, respectively. The mean pinch strength of the injured and opposite hands was 5.8 and 6.5 kg, respectively. The mean grip strength of the injured and opposite hands was 39 and 40 kg, respectively. We noted mild recipient joint pain in 6 patients and mild donor joint pain in 1 patient. The mean score of the Disabilities of the Arm, Shoulder, and Hand questionnaire was 9.

CONCLUSIONS

We used an osteoarticular pedicle flap from the capitate to resurface traumatic defects of the head of the proximal phalanx. This approach is acceptable for restoring the contour of the phalangeal head.

A novel hamatometacarpal fracture-dislocation classification system based on CT scan

PURPOSE

The purpose of this study was to devise a novel classification of a hamatometacarpal fracture-dislocation based on the preoperative computed tomography (CT) and plain radiography that provided more information to surgeons regarding appropriate treatment methods.

MATERIALS AND METHODS

Twenty-one patients with a hamatometacarpal fracture-dislocation were enrolled in this study. The classification scheme devised for hamatometacarpal fracture-dislocation is summarised as follows: type I - a simple dislocation; type IIA - a dislocation with the fourth metacarpal base intra-articular fracture; type IIB - a dislocation with a dorsal hamate fracture of less than one-third of the articular surface; and type III - a dislocation with a dorsal hamate fracture of more than one-third of the articular surface.

RESULTS

Type I injury was treated conservatively after closed reduction. Type IIA and IIB injuries were treated by percutaneous K-wire fixation. Type III injury was treated by open reduction and internal fixation. All injuries were well managed in both clinical and radiographic evaluations, without apparent complications.

CONCLUSION

The novel classification system for hamatometacarpal fracture-dislocation can be used to establish guidelines for appropriate treatment.

The paediatric wrist revisited--findings of bony depressions in healthy children on radiographs compared to MRI

BACKGROUND

The presence of erosions is used for diagnosis and monitoring of disease activity in juvenile idiopathic arthritis (JIA). Assessment of carpal bone erosions in children is challenging due to lack of normal references.

OBJECTIVE

To define normal appearances of bony depressions in the wrist on radiographs and MRI.

MATERIALS AND METHODS

MRI and radiography of the wrist were performed in 88 healthy children, 5-15 years of age. We assessed the number of bony depressions within the carpals/proximal metacarpals on both modalities, separately and combined.

RESULTS

A total of 75 carpal depressions were identified on radiography compared to 715 on MRI. The number of bony depressions identified radiographically showed no statistically significant difference across age-groups. Within the metacarpals, there was no significant difference between bony depressions identified by MRI or radiography, except at the bases of the second metacarpal.

CONCLUSION

Bony depressions that resemble erosions are normal findings in the wrist in children. MRI identifies more depressions than radiographs in the carpus. Some bony depressions occur at typical locations and should be accounted for when assessing the wrist in JIA to avoid overstaging.

Osseous and ligamentous scaphoid anatomy: Part II. Evaluation of ligament morphology using three-dimensional anatomical imaging

PURPOSE

There are many controversies in the literature regarding the morphology of the scaphoid ligaments. The aim of this study was to provide a more accurate description by quantitatively describing the 3-dimensional, geometrical aspects of the scaphoid ligaments and their attachments, using cryomicrotome images of cadaveric wrists.

METHODS

Eight fresh-frozen human cadaver wrists were examined with computed tomography (CT) and an imaging cryomicrotome. A series of 2-dimensional cryoimages created a 3-dimensional anatomical data set of each test specimen. Detection of ligaments and their surface areas was performed by manually marking the course and attachment points for each ligament, using dedicated visualization software. The 3-dimensional bone surfaces were segmented from the acquired CT images and incorporated in the 3-dimensional anatomical data set of the same anatomical specimen to facilitate the detection procedure. The results of the morphological parameters and attachment areas of the scaphoid ligaments are described 3-dimensionally.

RESULTS

The mean size of the whole scaphoid surface was 1503 ± 17 mm(2), and the mean size of all ligament attachments on the scaphoid was 131 ± 14 mm(2); thus, ligament attachments consist of 9% ± 0.9% of the total scaphoid surface area. Based on the data, a 3-dimensional representation of the wrist was created to present the scaphoid ligament attachment areas and paths. The dorsal intercarpal ligament had the most individual variability between specimens in attachments.

CONCLUSIONS

The quantitative results were almost completely consistent with the findings of previous reports. The only inconsistency in ligament morphology regarded the scaphocapitate ligament, which in this study was found to be the thickest ligament attached to the scaphoid.

CLINICAL RELEVANCE

The results of this study improve our knowledge of scaphoid ligament anatomy, as they corroborate previous findings. This is important for carpal surgery and will pave the way to a better understanding of the biomechanics involved in destabilization of wrist fractures.

Osseous and ligamentous scaphoid anatomy: Part I. A systematic literature review highlighting controversies

PURPOSE

The interpretation of scaphoid anatomy and kinematics is confusing and controversial. This results from a lack of consensus on the anatomy of the ligaments attaching to the scaphoid and an overwhelming variety of substantially different anatomic descriptions and classification systems of the wrist joint in the literature. The present study systemically reviews the consistencies or inconsistencies of the various scaphoid ligament descriptions and aims to clarify and unify different concepts and classification systems.

METHODS

We performed a systematic search of the medical literature from 1950 to 2010. We included all descriptive reports of the anatomy or morphology of the scaphoid, ligaments, or both. With the aim to describe the best available evidence, we considered all anatomical descriptions but emphasized a selection of the most frequently cited articles.

RESULTS

The literature search resulted in 555 potentially eligible descriptive reports, 58 of which met the inclusion criteria and were included in the review. Variations in the anatomic descriptions appear to be mostly due to the difficulty of identifying individual interdigitating ligaments or bundles by macroscopic dissections, as well as the interindividual variability in ligament anatomy. The most important areas of controversy in the scaphoid ligament attachments include the radial collateral ligament, dorsal radiocarpal ligament, dorsal intercarpal ligament, volar scaphotriquetral ligament, and scaphotrapezium-trapezoid ligament.

CONCLUSIONS

None of the scaphoid ligaments other than the scaphocapitate ligament have been described consistently. Future research is required to verify the ligament attachments that currently have the most controversial descriptions, while addressing the interindividual variability of ligament insertions and morphology.

CLINICAL RELEVANCE

Thorough knowledge of the anatomy will enhance our understanding of the kinematics of the scaphoid.

Wrist anatomy and biomechanics

Anatomic and biomechanical research of the wrist has yielded a substantial amount of information that improves our basic knowledge of carpal morphology and function of the wrist and provides information to better assess and improve treatment(s) for various problems of the wrist joint. A precise knowledge of the anatomy and biomechanics of the wrist is useful not only for diagnosis of traumatic ligamentous injuries or degenerative change of the wrist joint but also for treatment for wrist dysfunction.

Incidence of carpal boss and osseous coalition: an anatomic study

PURPOSE

To determine the incidence of a clinically evident carpal boss (bony prominence on the dorsal aspect of the second and/or third carpometacarpal joint) and by means of dissection to determine the incidence of osseous coalitions and any abnormality or absence of associated ligament anatomy in the second through fifth carpometacarpal joints in a cadaver population.

METHODS

The area of the second through fifth carpometacarpal joints was dissected in 202 cadaver wrists.

RESULTS

Thirty-nine of the wrists had a bony prominence and partial osseous coalition between 2 or more of the capitate, trapezoid, second metacarpal, and third metacarpal bones. When an osseous coalition was present it was incomplete, located at the dorsal aspect of the joint, and there was an absence of the normal dorsal ligaments at that joint. Ten of the 87 pairs of wrists were found to have bilateral carpal bosses with partial dorsal osseous coalition. The most common location of the osseous partial coalition was between the second metacarpal and the trapezoid. There were no osseous coalitions or absence of the normal dorsal ligaments at the fourth and/or fifth carpometacarpal joints.

CONCLUSIONS

This study showed that there was a high percentage of partial osseous coalitions with an associated prominence of the skeletal anatomy in the general cadaver population. The etiology of the carpal boss remains unclear.

Variations of capitate morphology in the wrist

PURPOSE

This anatomical study details and categorizes variations in capitate morphology and associated structures in the human cadaveric wrist.

METHODS

We dissected 107 cadaveric wrists. Capitate morphology, the presence of capitate and hamate ridges, the lunate types, and the width of the medial hamate facet of type II lunates and 4th carpometacarpal joint types were recorded.

RESULTS

Three types of capitate were identified. The flat type (69/107, or 65%) was characterized by a horizontally oriented (radio-ulnar) lunate-capitate articulation and a longitudinally oriented (proximal-distal) scaphoid-capitate articulation. The flat type was associated with type I lunates or type II lunates with a smaller facet. The spherical type (23/107, or 22%) was associated with a concave articulation formed by the scaphoid and lunate articulations, with an indistinct border between the scaphoid and lunate facets. The width of the medial hamate facet of type II lunates in wrists with a spherical-type capitate was <or=4 mm. The V-shaped type (15/107, or 14%) was characterized by separate lunate and scaphoid facets that converge, forming a V-shape. All the V-shaped capitates had a type II lunate with a large facet.

CONCLUSIONS

A relationship was found between the 3 capitate types and both the lunate types and the width of the medial hamate facet of the type II lunates. Further study is warranted to determine if these differences in capitate morphology influence the development or progression of various wrist pathologic conditions, such as Kienböck's disease and post-traumatic arthritis associated with scapholunate dissociation and scaphoid nonunion, and the outcome of certain surgical procedures, such as a proximal row carpectomy.