Proximal Capitate Research Articles

PRC with Double Interposition Arthroplasty for Failed Partial Wrist Arthrodesis

Abstract Background In patients with lunate fossa and proximal capitate degeneration, or failed scaphoid excision and partial wrist arthrodesis, double allograft interposition arthroplasty may allow patients to maintain wrist motion and improve pain. Description of Technique Following dorsal exposure of the carpus, a completion proximal row carpectomy is performed. Suture anchors are placed evenly along the perimeter of the distal radius and used to secure a precut sheet of allograft. Additional suture anchors are placed at the proximal aspect of the distal carpal row, securing a second piece of allograft to the proximal capitate and hamate. Patients, Methods, and Results We present the case of a female with osteogenesis imperfecta who failed prior partial wrist fusion for treatment of scapholunate advanced collapse. She declined wrist arthrodesis and was not a candidate for total wrist arthroplasty. Proximal row carpectomy with double interposition arthroplasty provided resolution of her pain and preserved her wrist range of motion. Conclusions Double interposition arthroplasty may provide reliable pain relief and wrist range of motion for patients with advanced wrist arthritis in whom traditional salvage procedures are contraindicated or have failed. Use of this technique offers benefits that may minimize complications and improve longevity compared with previously described allograft interposition techniques.

Midterm Clinical Outcomes of a Resurfacing Capitate Pyrocarbon Implant: A Case Series

Abstract Purpose Scaphoid nonunion advanced collapse (SNAC), scapholunate advanced collapse (SLAC), and Kienbock's disease are some of the most common pathologies to result in arthritis of the wrist in patients with a relatively high functional demand. An option for treatment where there are not two cartilage surfaces suitable for articulation to allow either a proximal row carpectomy (PRC) or partial fusion is to perform a PRC combined with resurfacing of the capitate using a pyrocarbon implant (RCPI). The purpose of this study was to examine the medium-term survivorship, clinical-, and patient-reported outcomes of the RCPI in a case series of patients. Methods Survivorship was assessed in 46 patients at approximately 21 months or greater (range = 21–144, median follow-up = 67). Of these, 36 patients completed patient-reported outcome measures (Visual Analogue Scales, Disabilities of the Arm, Shoulder and Hand–short form, Patient-Rated Wrist Evaluation, Global Rating of Change) at 21 months or greater. Patient population was 42% (n = 16) female, average age was 59 (range = 25–79), and majority had the operation on their right hand (78%, n = 35). Results Implant survival can be confirmed until most recent follow-up at a median of 60 months (range = 21–144), with Kaplan–Meier analysis indicating an 83% survival probability at 10 years. Complications at 21 months or greater were observed in 11 patients (24%), with 9 (20%) patients receiving further surgery (7 wrist fusions, 1 ulnar nerve decompression, and 1 distal radioulnar joint replacement [RCPI in situ]). Time to revision was a mean of 20 months (range = 4–39). Comparison between passive range of motion at 21 months to 4 years and >5 years showed no significance (p > 0.5), suggesting 2- to 4-year outcomes are maintained midterm. Conclusions The RCPI extends the indications for PRC where there is unsatisfactory cartilage on the proximal capitate, the lunate facet of the radius, or both. It provides a safe and effective treatment for pain relief and improved functional use of the hand for SLAC and SNAC arthritis without the increased morbidity of more complex arthroplasty or total wrist arthrodesis. Level of Evidence IV, case series

A novel means of capitate distraction lengthening for end-stage Kienböck's disease.

We present a patient with Kienböck's disease treated with a novel technique of capitate distraction lengthening using two wires in the proximal capitate and two in the ulna.

Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart-thrower's motion.

This research examines whether the distribution of trabecular bone in the proximal capitates of extant hominids, as well as several fossil hominin taxa, is associated with the oblique path of the midcarpal joint known as the dart-thrower's motion (DTM). We analyzed proximal capitates from extant (Pongo n = 12; Gorilla n = 11; Pan n = 10; fossil and recent Homo sapiens n = 29) and extinct (Australopithecus sediba n = 2; Homo naledi n = 1; Homo floresiensis n = 2; Neandertals n = 3) hominids using a new canonical holistic morphometric analysis, which quantifies and visualizes the distribution of trabecular bone using relative bone volume as a fraction of total volume (rBV/TV). Homo sapiens and Neandertals had a continuous band of high rBV/TV that extended across the scaphoid, lunate, and hamate subarticular regions, but other fossil hominins and extant great apes did not. A. sediba expressed a distinct combination of human-like and Pan-like rBV/TV distribution. Both H. floresiensis and H. naledi had high rBV/TV on the ulnar-side of the capitate but low rBV/TV on the radial-side. The proximal capitates of H. sapiens and Neandertals share a distinctive distribution of trabecular bone that suggests that these two species of Homo regularly load(ed) their midcarpal joints along the full extent of the oblique path of the DTM. The observed pattern in A. sediba suggests that human-like stress at the capito-scaphoid articular surface was combined with Pan-like wrist postures, whereas the patterns in H. floresiensis and H. naledi suggest their midcarpal joints were loaded differently from that of H. sapiens and Neandertals.

Coronal translation of the forearm, proximal capitate, and ulnar styloid predict radial inclination in distal radius fractures in older female patients.

The aims of this study were to identify means to quantify coronal plane displacement associated with distal radius fractures (DRFs), and to understand their relationship to radial inclination (RI). From posteroanterior digital radiographs of healed DRFs in 398 female patients aged 70 years or older, and 32 unfractured control wrists, the relationships of RI, quantifiably, to four linear measurements made perpendicular to reference distal radial shaft (DRS) and ulnar shaft (DUS) axes were analyzed: 1) DRS to radial aspect of ulnar head (DRS-U); 2) DUS to volar-ulnar corner of distal radius (DUS-R); 3) DRS to proximal capitate (DRS-PC); and 4) DRS to DUS (interaxis distance, IAD); and, qualitatively, to the distal ulnar fracture, and its intersection with the DUS axis. In the study (fracture) and control groups, respectively, the mean values were: RI, 17.2° (SD 7.2°; -7° to 35°) and 25.6° (SD 2.6°; 21° to 30°); DRS-U, 13.5 mm (SD 1.7; 4.9 to 20.8) and 15.3 mm (SD 0.72; 13.8 to 16.3); DUS-R, 13.4 mm (SD 2.1; 4.8 to 18.5) and 12.0 mm (SD 0.99; 9.7 to 13.9); DRS-PC (positive value radial to DRS, negative value ulnar), 0.14 mm (SD 5.4; -10.9 to 22.7) and -6.1 mm (SD 1.6; -10.6 to -2.3); and IAD, 25.3 mm (SD 2.5; 17.6 to 31.1) and 27.1 mm (SD 1.5; 24.5 to 31.0). All means were significantly different between the study and control groups. RI correlated strongly with DRS-PC. Ulnar styloid fracture intersection with the DUS axis, reflective of ulnar translation of both radial and ulnar shafts, was associated with significantly lower RI. After DRF, the relationship of the proximal capitate to the DRS axis in the coronal plane correlates with the final radial inclination. Additionally, ulnar styloid intersection with the DUS axis is associated with even lower radial inclination. DRF reduction should seek to restore the normal coronal relationship of both radial and ulnar shafts to their distal counterparts.

Long-term results of first row carpectomy with proximal capitate resurfacing using a pyrocarbon implant.

The functional results of proximal row carpectomy with a proximal capitate resurfacing using a pyrocarbon implant were evaluated in a retrospective, multicentric, multi-operator study. The outcomes of patients operated on at five surgical centres between January 2005 and December 2018 were reviewed. The data were collected by an independent observer during standardized consultations. Based on 30 patients with a mean follow-up of 7 years, the median range of flexion and extension was 65° and the median radioulnar tilt was 45°. The median Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score was 14 and the improvements in strength and pain were good. Compared with the preoperative values, significant improvements were seen in the flexion and extension range of motion, radioulnar tilt and pain score. No postoperative complications were recorded.Level of evidence: IV.

Classification and Radiographic Characterization of Kienböck Disease.

Robert Kienböck described radiographic changes associated with idiopathic lunate osteonecrosis in 1910. The radiographic progression of this eponymous condition has been well-described to progress from normal radiographs, to lunate sclerosis, lunate collapse, proximal capitate migration, scaphoid flexion, and pancarpal arthritis. Diagnosing early stages of the disease without radiographic changes presented a challenge. As imaging modalities have evolved, diagnosis has become possible with MRI. Although numerous classification systems exist, the Lichtman classification and the Bain arthroscopic grading system have become widely used. This article outlines the available classification systems and aims to highlight when each may be useful in patient management.

Lateral Femoral Trochlea Flap Reconstruction of the Proximal Capitate: An Assessment of Congruity and Description of Technique

We examined morphologic similarities of the medial lateral femoral trochlea (MFT) and lateral femoral trochlea (LFT) osteochondral flaps for reconstruction of the proximal capitate. Magnetic resonance imaging scans of the wrists and ipsilateral knees of 10 young healthy volunteers were obtained. Three morphologic parameters were investigated, comparing the MFT and LFT harvest sites to the capitate proximal pole. The correspondingly relevant surgical planes were compared. The coronal plane radius of curvature (ROC) of the capitate was compared with the sagittal planes of the MFT and LFT. The sagittal plane ROC of the capitate was compared to the axial planes of the MFT and LFT. The angular relationship between the dorsal cortical surface of the capitate and the proximal pole cartilage (proximal dorsal capitate pitch) was compared to the corresponding angles between the cortical bone and convex cartilage on the LFT and MFT. The average ratios of ROC for the coronal planes of the capitate to the MFT (0.61) and LFT (0.58) were similar. The average ratios of ROC for the sagittal planes of the capitate to the MFT (0.57) and LFT (0.86) were also similar. The proximal dorsal capitate pitch demonstrated greater similarity to the corresponding shape of the LFT (angular ratio, 1.01) than to that of the MFT (angular ratio, 0.74). The LFT and MFT demonstrate similar congruity to the proximal capitate in the sagittal and coronal planes of the wrist. The LFT dorsal pitch closely approximates the relationship of the proximal capitate pole to its dorsal cortical surface. In capitate fracture, fracture nonunion, or avascular necrosis, both the MFT and LFT demonstrate similarity to the proximal convex capitate morphology. The relationship between the cortical and chondral surfaces of the LFT is morphologically very similar to that of the proximal capitate.

Proximal Row Carpectomy Modifications for Capitate Arthritis: A Systematic Review.

Introduction Proximal row carpectomy (PRC) is a motion-sparing procedure for radiocarpal arthritis with reliable results. Traditionally, proximal capitate arthritis is a contraindication to PRC; however, PRC with modifications are proposed to circumvent this contraindication. PRC modifications can be broadly grouped into capitate resurfacing (CR) and capsular interposition (CI) procedures which could expand PRC indications. Our primary question was to characterize the outcomes achievable with various PRC modifications. Our secondary question was to determine which PRC modification was the optimal procedure when capitate arthritis was present. Methods A systematic review was conducted to examine the outcomes of modified PRC procedures. Independent reviewers appraised multiple databases for PRC studies with modifications for capitate arthritis in adult patients (age >18 years) with a minimum of three cases and extractable outcomes. Modified PRC procedures included capsular/allograft interposition, resurfacing capitate pyrocarbon implants, and osteochondral grafting. Pertinent outcomes included patient demographics, range-of-motion, grip strength, patient-reported outcomes, and complications, including salvage rates. Results Overall, 18 studies met the inclusion criteria-10 studies ( n = 147) on CI and 8 studies on CR ( n = 136). PRC with CI had the greatest flexion-extension arc and grip strength. Complications were marginally higher in the CR group (4%), while the CI group had a higher conversion to total wrist arthrodesis (10%). Conclusion Techniques to address capitate arthritis center around resurfacing or soft tissue interposition. PRC modifications with CI produces better range-of-motion and grip strength but higher conversion to total wrist arthrodesis. Higher conversion rates may be attributable to longer follow-up periods in studies examining CI compared with CR. Level of Evidence This is a Level III study.

Medial femoral trochlea flap reconstruction versus proximal row carpectomy for Kienböck's disease: a morphometric comparison.

Surgical options for advanced Kienböck's disease include proximal row carpectomy or lunate reconstruction with a medial femoral trochlea osteochondral flap. This study compares morphology of the proximal capitate and the medial femoral trochlear surfaces to the proximal lunate using three-dimensional geometric morphometric analysis. Virtual articular surfaces were extracted from MRI studies of ten healthy volunteers. Distances between corresponding points on the proximal lunate and proximal capitate or medial femoral trochlear surfaces were measured. In seven subjects, mean inter-surface distance for the medial femoral trochlea-proximal lunate pair was significantly lower than the proximal capitate-proximal lunate pairing. In three subjects, mean proximal capitate-proximal lunate distance was significantly lower. We conclude that the medial femoral trochlear flap was anatomically closer to the shape of the proximal lunate in the majority of the examined subjects. However, we found that in three out of ten cases, the proximal capitate was a better match.

Cortical and trabecular bone structure of the hominoid capitate.

Morphological variation in the hominoid capitate has been linked to differences in habitual locomotor activity due to its importance in movement and load transfer at the midcarpal joint proximally and carpometacarpal joints distally. Although the shape of bones and their articulations are linked to joint mobility, the internal structure of bones has been shown experimentally to reflect, at least in part, the loading direction and magnitude experienced by the bone. To date, it is uncertain whether locomotor differences among hominoids are reflected in the bone microarchitecture of the capitate. Here, we apply a whole‐bone methodology to quantify the cortical and trabecular architecture (separately and combined) of the capitate across bipedal (modern Homo sapiens), knuckle‐walking (Pan paniscus, Pan troglodytes, Gorilla sp.), and suspensory (Pongo sp.) hominoids (n = 69). It is hypothesized that variation in bone microarchitecture will differentiate these locomotor groups, reflecting differences in habitual postures and presumed loading force and direction. Additionally, it is hypothesized that trabecular and cortical architecture in the proximal and distal regions, as a result of being part of mechanically divergent joints proximally and distally, will differ across these portions of the capitate. Results indicate that the capitate of knuckle‐walking and suspensory hominoids is differentiated from bipedal Homo primarily by significantly thicker distal cortical bone. Knuckle‐walking taxa are further differentiated from suspensory and bipedal taxa by more isotropic trabeculae in the proximal capitate. An allometric analysis indicates that size is not a significant determinate of bone variation across hominoids, although sexual dimorphism may influence some parameters within Gorilla. Results suggest that internal trabecular and cortical bone is subjected to different forces and functional adaptation responses across the capitate (and possibly other short bones). Additionally, while separating trabecular and cortical bone is normal protocol of current whole‐bone methodologies, this study shows that when applied to carpals, removing or studying the cortical bone separately potentially obfuscates functionally relevant signals in bone structure.

Osteochondral Autograft Transplantation for Hand and Wrist Articular Problems.

Management of hand and wrist avascular necrosis with osteochondral fragmentation or focal arthritis can be a challenging problem with a variety procedures described for its treatment. Osteochondral autograft transplantation systems have been utilized in various focal defects of the knee, ankle, elbow, and wrist. The same principle for the treatment of focal defects of the proximal scaphoid, proximal capitate as well as metacarpal head as an alternative treatment is described. The main indication for this treatment is to address focal or partial osteochondral defects where the size of the defect is smaller than the isthmus of the involved bone to accommodate a cylindrical osteochondral graft that can be press fit. Larger and complete defects are contraindications to this treatment. We discuss the surgical technique as well as its main indications and expected outcomes.

Investment Proximity and Venture Capital Returns

Using a large dataset of 82,818 investments in start-up firms from December 1965 through August 2019, we document that the biggest group of investors are venture capital firms (about 79% of all observations). The majority of in-state investments are found clustered in California (with the San Francisco VC Hub), Massachusetts (with the Boston VC Hub) and New York. Returns generated from early round investing to late round decrease generally: early investors generate a higher return than late stage investors, and IPO exits entail the highest return. We find that geographical proximity is significantly and positively associated with cumulative returns or annualized returns, when we use actual distance (in km) between the VC investment firm HQ and portfolio firm HQ, or a cross-region indicator variable when the portfolio firm HQ is out-of-state as compared to VC investment firm HQ. The relation between investment proximity and returns continues to be robust even after controlling for selection bias, and in a matched-sample analysis where we pair each proximate investment with a matched distant investment. We find that VC Director and other outside directors as a proportion of all Directors on the boards on portfolio companies is significantly higher, on average, for in-state and shorter distance investments as compared to out-of-state or longer distance investments, indicating better involvement by VCs in their more proximate investments.

Distinct Wrist Patterns Founded on Measurements in Plain Radiographs.

Background In joints, structure dictates function and consequently pathology. Interpreting wrist structure is complicated by the existence of multiple joints and variability in bone shapes and anatomical patterns in the wrist. Previous studies evaluated lunate and capitate shape in the midcarpal joint, and two distinct patterns have been identified. Purpose Our purpose was to further characterize the two wrist patterns in normal wrist radiographs using measurements of joint contact and position. Our hypothesis was that we will find significant differences between the two distinct anatomical patterns. Patients and Methods A database of 172 normal adult wrist posteroanterior (PA) radiographs was evaluated for radial inclination, height, length, ulnar variance, volar tilt, radial-styloid-scaphoid distance, and lunate and capitate types. We measured and calculated percent of capitate facet that articulates with the lunate, scapholunate ligament, scaphoid, and trapezoid. These values were compared between the wrist types and whole population. Results Type-1 wrists (lunate type-1 and spherical proximal capitate) were positively associated with a longer facet between capitate and distal lunate ( p = 0.01), capitate and base of middle metacarpal ( p = 0.004), and shorter facet between the capitate and hamate ( p = 0.004). The odds ratio of having a type-1 wrist when the interface between the capitate and lunate measures >8.5 mm is 2.71 (confidence interval [CI] 1.07, 6.87) and when the line between the capitate and the base of middle metacarpal >9.5 mm is 3.5 (CI 1.38, 9.03). Conclusion We characterized the two-wrist patterns using intracarpal measurements. Translating these differences into three-dimensional contact areas may help in the understanding of biomechanical transfer of forces through the wrist. Level of Evidence This is a Level II, diagnostic study.

Trigger wrist caused by avascular necrosis of the capitate: a case report

BackgroundTrigger wrist is a rare condition first described by Marti in 1960, and various causes have been reported. The condition mostly occurs with finger flexion and extension, and rarely with flexion and extension of the wrist itself. Avascular necrosis of the capitate is also a rare condition, first described by Jönsson in 1942. While some reports of this condition have been published, little is known about its etiology. Therefore, no established treatment exists. We report a case of trigger wrist caused by avascular necrosis of the capitate.Case presentationA 16-year-old right-handed male who was a high school handball player was referred to our department from a nearby hospital 5 months after the onset of pain in the dorsal aspect of the right wrist, with an unknown cause. At the previous hospital, imaging findings led to a diagnosis of avascular necrosis of the capitate, and conservative treatment with a wrist brace did not improve the pain. At the initial visit to our department, the patient was noted to have a painful trigger wrist that was brought on by wrist flexion and extension. Preoperative imaging findings led to a diagnosis of trigger wrist caused by capitolunate instability secondary to avascular necrosis of the capitate. We performed a partial excision of the proximal capitate with tendon ball interposition. Two years after surgery, the patient’s clinical outcome was favorable, with no recurrence of wrist pain or triggering.ConclusionsBoth trigger wrist and avascular necrosis of the capitate are rare disorders. When a patient presents with painful triggering at the wrist, surgeons must bear in mind that avascular necrosis of the capitate may result in this phenomenon. We recommend partial excision of the proximal capitate with tendon ball interposition for the treatment of this lesion.

Meniscal Allograft Interposition Combined with Proximal Row Carpectomy.

Background Proximal row carpectomy (PRC) is contraindicated in wrists with preexisting arthritis of the proximal capitate or radiolunate fossa. Patients with these conditions frequently pursue wrist arthrodesis with its associated functional limitations. Questions/Purposes The purpose of this study was to evaluate the results of using lateral meniscal allograft interposition (LMAI), in combination with PRC, in patients with symptomatic wrist arthritis. The primary question is whether this allograft will allow wrist function comparable to that in patients having only a PRC. A secondary question was to determine the short-term longevity of the allograft. Patients/Method Between 2006 and 2012, nine wrists underwent PRC with LMAI. Patient demographics and rates of complication or graft failure were determined. During independent clinical exams, functional outcomes were reviewed, patients completed a Disabilities of the Arm, Shoulder, and Hand (DASH) scores, and radiographs were taken. Results Four patients met the inclusion criteria, having clinical follow-up at an average of 4.2 years. DASH scores at the time of follow-up ranged from 9 to 33, with an average of 24. Average radiocapitate joint space in the first postoperative radiograph was 2.8 mm compared with 1.8 mm at the time of final follow-up. No wrists went on to arthrodesis. Conclusion Early outcomes of PRC with LMAI are comparable to those results found in the literature of PRC alone. LMAI with PRC may be a valid short-term option as a motion-preserving procedure in those patients contraindicated to having a PRC alone. Level of Evidence Level IV.

The role of MNCs and information flow on institutional change

Purpose – The purpose of this paper is to investigate the impact of large business corporations, particularly media corporations, such as television (e.g. satellite networks), newspapers and social media (e.g. Facebook), on institutional change in the Arab world, which directly impact political and civil liberties in the region. Design/methodology/approach – Although there are several methods to measure institutional change, this paper relied on Kaufmann et al. (2010)’s governance indicators that capture, historically, how authority is exercised in a nation state. As the focus of this paper is on how information flows have empowered citizens in the Arab world, we built a panel database around one relevant governance indicator: “Voice and Accountability”. As a measure of governance, “Voice and Accountability” summarizes the condition of political, civil and human rights such as freedom of expression and freedom of association in a given country. This indicator takes scores ranging from 2.5, corresponding to strong governance, to −2.5, corresponding to weak governance. Findings – As predicted, the information flows variable has a positive and significant effect on institutional change. Table II also suggests that political globalization has a positive and significant effect on institutional change in the Arab world. In contrast, the variables for cultural proximity and human capital are associated with negative effects on institutional change. Originality/value – This paper is unique in the sense that it tackles a growing trend in the Arab world, namely, the impact of media on institutions.

Wrist Pain- Baseball Pitcher

HISTORY: A 16 year old high school baseball pitcher presented in July with persistent right wrist pain for 2 months after slipping at the beach. Initial exam revealed only ulnar sided wrist tenderness. A radiograph showed no fractures, with a small lucency in the capitate resembling a bone cyst. He was managed as a sprain with splinting, rest, ice and NSAIDs. He returned to daily activities, but noted worsening pain in September, specifically with weightlifting and deadlifts. His course was complicated by acute severe hand swelling, prompting an urgent clinic visit. PHYSICAL EXAM: BP: 122/80; HR: 78; Temp: 36.6 Severe swelling noted on the dorsal right wrist without erythema, bruising, lacerations, nail infection or skin breakdown, and no extension proximally. He had 5/5 strength in all directions, but with pain on flexion and extension of the wrist without a humpback deformity. Dorsal and volar aspects of the wrist were painful over the capitate and lunate, without anatomic snuffbox tenderness or scaphoid shift. Distal radioulnar joint tenderness was not as severe as his previous visit. Radial pulses and sensation to light touch bilaterally were normal. Concern over the acuity and severity of his wrist swelling prompted repeat imaging with an x-ray and MRI, as well as blood work. DIFFERENTIALS: 1.Wrist sprain 2.Carpal stress fracture 3.Synovitis 4.Infection 5.Tumor 6.Rheumatoid Arthritis TESTS/RESULTS: WBC- 7 Hemoglobin/Hematocrit- 15/45 Platelet- 257 Rheumatoid Factor- 6.7 Vitamin D25- 40 ANA- negative CRP- 3 ESR- 2 Right Wrist X-Ray: _ No acute fracture or dislocation _ Persistent stable lucency in proximal capitate. Right Wrist MRI _ diffuse signal abnormality in lunate with negative ulnar variance in keeping with Kienbock’s Disease _ Soft tissue edema on dorsal wrist adjacent to lunate and capitate and deep to extensor tendons _Thickening and heterogenous signal involving dorsal extrinsic ligaments predominantly at capitate and lunate compatible with sprain FINAL/WORKING DIAGNOSIS: Kienbock’s Disease Stage 1 TREATMENT/OUTCOME: 1.Intermittent immobilisation during the day when symptomatic and continuously at night 2.Counseled on disease progression and future need for surgery 3.Referred to an Orthopedic Hand Specialist for surgical options, with a re-evaluation in 6 months by MRI

Radiocapitate Congruency as a Predictive Factor for the Results of Proximal Row Carpectomy

To evaluate whether the congruency between the joint surfaces of the lunate fossa of the distal radius and the proximal capitate might be a prognostic factor for functional, clinical, or radiographic results after proximal row carpectomy (PRC). After reconstructing the computed tomographic arthrogram of patients with PRC, we evaluated the shape of the proximal capitate by measuring the radius of curvature of the tip of the capitate. The congruency of the future radiocapitate joint was then evaluated by the radiocapitate index in the frontal and sagittal planes. This was calculated by dividing the radius of curvature of the tip of the capitate by the mean radius of curvature of the lunate fossa. We determined the relationship between these morphological results and the functional (Disabilities of the Arm, Shoulder, and Hand [DASH] score, Mayo Wrist score, and pain relief), clinical (mobility and strength) and x-ray results (radiocapitate arthrosis). A total of 27 patients were reviewed at a mean follow-up of 59 months. The shape of the proximal capitate did not affect outcomes. In the frontal plane, a better radiocapitate congruency was significantly associated with an increase in wrist flexion and better functional results for the DASH. There was a non-significant relationship between congruency and improvement of Mayo Wrist score and pain relief. In the sagittal plane, the DASH score tended to improve when congruency was better. The shape of the capitate was not a prognostic factor for functional outcome after PRC. The radiocapitate index seems more relevant in predicting results at last follow-up. Prognostic II.

Relative accuracy of spin-image-based registration of partial capitate bones in 4DCT of the wrist

In image-based biomechanical analyses, registration transformations are the data of interest. In dynamic four-dimensional computed tomography (4DCT) imaging, the capitate is often partially imaged. While alignment of incomplete objects poses a significant registration challenge, the established spin-image surface-matching algorithm can be utilised to align two surfaces representing disparate but overlapping portions of an object. For this reason, the spin-image algorithm was chosen for the registration of partial bone geometry in 4DCT of the wrist. Registrations were performed on 11 4DCT datasets using complete and partial capitate meshes generated by cropping complete meshes. Relative accuracy was assessed as the difference between partial- and complete-geometry registrations. Accurate registration of partial capitate geometry was achieved with 55% of the proximal capitate geometry on average, and in some cases as little as 35%. Requisite geometry depends on feature salience and imaging resolution; however, the spin-image algorithm should be considered a valuable tool for biomechanists and image analysts.