Examining the Efficacy of Arthroscopic Scaphocapitate Arthrodesis for Advanced Kienbock's Disease: Clinical and Radiological Outcomes.

Background: Altering wrist biomechanics, Kienbock's disease leads to progressive carpal collapse that results in early arthritis and degenerative changes. By shifting the loading axis toward the radioscaphoid joint, scaphocapitate arthrodesis (SCA) has been reported as a salvage procedure effective in treating symptomatic patients with advanced Kienbock's disease. In this study, we aimed to evaluate the clinical and radiological outcomes of arthroscopic SCA in symptomatic patients with advanced stages of Kienbock's disease. Methods: Between March 2010 and February 2021, we included 15 patients with symptomatic stage IIIA (n=2) and stage IIIB (n=13) Kienbock's disease who were followed up for a minimum of 24 months after arthroscopic SCA with or without lunate excision. The lunate was excised in 6 patients and retained in 9. Visual analog scale (VAS) pain score, grip strength, range of motion (ROM), active flexion-extension arc, and modified Mayo wrist score (MMWS) were measured preoperatively and at each follow-up examination after surgery. Operation-related complications and radiographic changes were also assessed. Results: There were 13 women and 2 men, with a mean age of 57.6 years (range, 21-74 years) at the time of undergoing arthroscopic SCA. Follow-up ranged from 24 to 116 months, with an average of 56.9 ± 32.3 months. Bony union was achieved in all patients. At preoperative examination, wrist ROM (67%) and grip strength (48%) significantly decreased, compared to the contralateral wrist. At the final follow-up, there were significant improvements in VAS, grip strength, and MMWS, whereas the active wrist ROM showed no significant change. Radioscaphoid angle recovered after surgery, while radiographic carpal collapse and ulnar translation of the carpus occurred. In subgroup analysis according to excision of the lunate, there were no significant differences in VAS, MMWS, grip strength, or total ROM. However, increased ulnar translation and decreased radial deviation were noted in the lunate excision group. Conclusions: Arthroscopic SCA achieved significant improvements in pain and wrist function in patients with advanced Kienbock's disease without any complications. Excision of the lunate when performing arthroscopic SCA seemed to induce progressive carpal ulnar translation, with no apparent clinical benefits over retaining it.

Idiopathic Avascular Necrosis of the Capitate Treated with a Medial Femoral Trochlea Vascularized Osteochondral Flap: A Case Report.

CASE: Capitate avascular necrosis should be entertained in a differential diagnosis of young, active adults with midcarpal wrist pain. We present a case study of a 30-year-old laborer who developed avascular necrosis (AVN) of his right proximal capitate. Grip strength and wrist motion were limited on examination, with advanced imaging confirming AVN. A diagnostic arthroscopy confirmed the pathology. Treatment was completed with a medial femoral trochlea vascularized flap for cartilaginous resurfacing. At 10-month follow-up, the patient's capitate was healed with stable fixation, and he is working full-time as a laborer without restrictions. CONCLUSION: AVN of the capitate is a unique and challenging articular pathology that requires a thoughtful preoperative evaluation and meticulous surgical technique to reconstruct. The medial femoral trochlea (MFT) vascularized bone transfer with cartilaginous resurfacing is 1 available treatment option. This flap is harvested from the medial femur using microsurgical techniques, based on the descending genicular artery. Using a 2-surgeon approach, simultaneous dissection of the AVN is completed at the wrist. This flap is a vascularized option that can be used for both AVN and nonunion with structural deformity before salvage surgeries.

Proximal Row Carpectomy with and without Capitate Resurfacing: A Preliminary Systematic Review and Meta-Analysis.

BACKGROUND: In wrist salvage, proximal row carpectomy (PRC) has increasingly shown superior outcomes to four-corner fusion (4CF). Furthermore, PRC with resurfacing capitate pyrocarbon implants (PRC + RCPIs) provides a treatment option that may allow patients to avoid 4CF or wrist arthrodesis and help restore natural joint function and distribute loads evenly across the implant, though RCPI has yet to be evaluated on a large scale. We aimed to compare outcomes between PRC and PRC + RCPI for the treatment of scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) wrists. METHODS: A systematic review and meta-analysis was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed/MEDLINE, Embase, Web of Science, and Cochrane were queried for articles on PRC and PRC + RCPI performed for SLAC and SNAC wrist with minimum 12-month follow-up. Primary outcomes included wrist range of motion (ROM), grip strength, and outcome scores including Disabilities of Arm, Shoulder, and Hand (DASH) and QuickDASH scores, Patient-Rated Wrist and Hand Evaluation (PRWHE), and visual analog scale pain scores. RESULTS: Twenty-two studies reporting on 1,804 wrists were included (1,718 PRC alone, 86 PRC + RCPI). PRC + RCPI was associated with greater postoperative radial deviation, but poorer flexion. PRC + RCPI also had significantly lower postoperative QuickDASH (less disability and symptoms) and postoperative PRWHE (lower pain and disability) scores and an improvement in PRWHE compared with PRC. There was no significant difference in grip strength. CONCLUSION: PRC + RCPI demonstrated similar postoperative ROM to PRC alone. While PRC + RCPI was associated with more favorable outcome scores, further research is needed to confirm these findings and assess the incidence and profile of complications related to RCPIs. LEVEL OF EVIDENCE: Level IV. See Instructions for Authors for a complete description of levels of evidence.

A novel capitate bone Ilizarov external fixator for treating Kienböck's disease: an anatomical and biomechanical study.

This study aims to measure anatomical data of the capitate bone, develop an external fixator for treating late-stage osteonecrosis of lunate through Ilizarov technique, and evaluate its biomechanical performance. We selected eight wrist joint specimens to measure various parameters of the capitate bone, including its length, the distance from the junction of capitate head and body to the proximal end, as well as the width of its proximal head and distal body. Additionally, we measured these same indicators in 107 patients who had undergone wrist X-ray examination. Based on our measurements, we categorized the capitate bone into two groups and designed two types of capitate bone Ilizarov external fixator (CIEF) for it. Then, we compared it with the orthofix external fixator (OEF) through dynamic fatigue biomechanical experiments and pull-out resistance experiments. The results of the measurement revealed two categories of general patterns in the capitate bone. The first type maintains a consistent longitudinal axis between the proximal and distal ends. The second type is characterized by its proximal end being close to the radial side and its distal end being close to the ulnar side. In the dynamic tensile fatigue test, CIEF-A and CIEF-B had smaller maximum displacement values compared to the OEF (P < 0.05). In the anti-pull-out experiment, both CIEF-A and CIEF-B exhibited higher maximum pull-out force than the OEF (P < 0.05). CIFE is a treatment for advanced osteonecrosis of the lunate bone. It is specifically designed to align with the anatomical characteristics of the capitate bone, providing excellent biomechanical properties and a simple clinical procedure. However, additional clinical experiments are needed to confirm its effectiveness in the future.

An anatomic study of the morphologic characteristics of the dorsal capitolunate ligament.

PURPOSE: There is consensus in favor of a description of the dorsal ligaments of the carpus as not including a direct ligament between the lunate and capitate. On the other hand, there is an anatomical formation which, according to the currently accepted description, corresponds to the dorsal midcarpal capsule, itself thickened by the dorsal intercarpal ligament. The question is whether the capsule at this point deserves to be called an individualizable ligament. In our operative experience of the dorsal carpus, we have encountered a stout structure adherent to the lunate and capitate. In this article, we present the anatomic evidence of this structure's existence. METHODS: Seven adult fresh frozen upper extremities were dissected. Three wrists were longitudinally sectioned in line with the middle finger metacarpal. The remaining 4 were dissected dorsally. Two representative samples of the stout structure connecting the lunate to the capitate were sent to pathology for histologic analysis and staining. RESULTS: In all 3 of the longitudinally sectioned wrists, a thick band of tissue could clearly be seen, originating on the lunate, spanning the dorsal interval between the lunate and the capitate, and inserting on the capitate. With this structure intact, dorsal dislocation of the capitate was not possible, but preliminary sectioning of the structure allowed dislocation. In the 4 dorsally dissected wrists, the same connection was observed, palmar to the dorsal intercarpal ligament, in every specimen. The average dimensions of the dorsal capitolunate were: 15.25 ± 1 mm long, 8.75 ± 1 mm wide at the midpoint, and 1.75 ± 1 mm thick. The two specimens sent to pathology after sectioning showed longitudinally oriented collagen fibers. This structure also stained positive for elastin and contained intrasubstance vascular structures. CONCLUSION: There is a stout ligamentous structure connecting the lunate to the capitate, palmar to the dorsal intercarpal ligament. Disruption of this structure appears to be necessary for dorsal dislocation of the capitate. Clinical studies are needed to gain better understanding of the exact function and importance of this structure.

Validation of radiographic assessment of radiocarpal (mal)alignment in a normal population.

We measured radiocarpal alignment in 150 standard lateral radiographs of normal wrists. In 84% of the cases, the lines of the long axis of the capitate and radius did not cross within the carpus.

Management of capitate avascular necrosis in an adult with a free medial femoral condyle flap.

The treatment of the extremely uncommon avascular necrosis of the capitate with a medial femoral condyle corticocancellous free flap has been described previously by one group reporting on outcomes in a paediatric patient. However, no literature to-date has detailed results of this procedure in an adult. We illustrate the case of a 53-year-old man who sustained capitate avascular necrosis and tendon rupture of traumatic aetiology. He was managed by resection of the necrotic segment, followed by inset of the medial femoral condyle free flap with the novel applications of indocyanine green to ensure adequate perfusion and intramedullary cannulated screw fixation of the capitate. Tendon transfer was also performed in the same operative sitting. At 9 months postoperatively, the patient displayed full range of motion of the wrist without any pain, and the imaging demonstrated union. This microsurgical approach may be performed in adult patients with favourable postoperative outcomes.

Immediate Proximal Row Carpectomy for Severe Perilunate Dislocation Injuries: A Minimum 5-Year Follow-Up.

Background: In patients with perilunate injuries (PLI) with multiple ligamentous and bony injuries involving the proximal carpal row, open reduction and internal fixation (ORIF) can be difficult and lead to poor functional outcomes. Proximal row carpectomy (PRC) is an alternative procedure that has been used for severely comminuted fractures. The aim of our study is to evaluate the long-term functional outcome (minimum 5 years) of patients that underwent an emergency PRC for PLI. Methods: We conducted a retrospective study of patients who underwent PRC at our centre between 2001 and 2016. Only patients with follow-up data of more than 5 years were included in the study. We evaluated range of motion, grip strength, Mayo Modified Wrist Score (MMWS) and Quick Disabilities of Arm, Shoulder and Hand (Quick-DASH). Radiographic analyses were performed to assess the presence of radiocarpal osteoarthritis and the space between the radius and capitate. Results: Thirteen patients were included, with an average follow-up of 78.07 months (6.5 years). The MMWS was 65 points (four excellent and good, four fair and five poor results) and the Quick-DASH score was 30 points. X-ray analysis reported only 15.3% of patients with radiocarpal arthrosis and an average radio-capitate joint space of 1.92 mm. Conclusions: The outcomes of PRC in the management of PLI are comparable to the results reported in literature for conventional ORIF. PRC is a simpler procedure that minimises the need for re-intervention. Level of Evidence: Level IV (Therapeutic).

Scapho-luno-capitate fusion with proximal lunate articular surface preservation for management of grade IIIA Kienböck's disease: a prospective case series.

BACKGROUND: Kienböck's disease is idiopathic lunate avascular necrosis, which may lead to lunate collapse, abnormal carpal motion and wrist arthritis. The current study aimed to assess the outcomes of treating stage IIIA Kienböck's disease by a novel technique of limited carpal fusion via partial lunate excision with preservation of the proximal lunate surface and scapho-luno-capitate (SLC) fusion. MATERIALS AND METHODS: We conducted a prospective study of patients with grade IIIA Kienböck's disease managed with a novel technique of limited carpal fusion comprising SLC fusion with preservation of the proximal lunate articular cartilage. Autologous iliac crest bone grafting and K-wires fixation were used to enhance the osteosynthesis of the SLC fusion. The minimum follow-up period was 1 year. A visual analog scale (VAS) and the Mayo Wrist Score were utilized for the evaluation of patient residual pain and functional assessment, respectively. A digital Smedley dynamometer was used to measure the grip strength. The modified carpal height ratio (MCHR) was used for monitoring carpal collapse. The radioscaphoid angle, scapholunate angle, and the modified carpal-ulnar distance ratio were used for the assessment of carpal bones alignment and ulnar translocation of carpal bones. RESULTS: This study included 20 patients with a mean age of 27.9 ± 5.5 years. At the last follow-up, the mean range of flexion/extension range of motion (% of normal side) improved from 52.8 ± 5.4% to 65.7 ± 11.1%, P = 0.002, the mean grip strength (% of normal side) improved from 54.6 ± 11.8% to 88.3 ± 12.4%, P = 0.001, the mean Mayo Wrist Score improved from 41.5 ± 8.2 to 81 ± 9.2, P = 0.002, and the mean VAS score reduced from 6.1 ± 1.6 to 0.6 ± 0.4, P = 0.004. The mean follow-up MCHR improved from 1.46 ± 0.11 to 1.59 ± 0.34, P = 0.112. The mean radioscaphoid angle improved from 63 ± 10º to 49 ± 6º, P = 0.011. The mean scapholunate angle increased from 32 ± 6º to 47 ± 8º, P = 0.004. The mean modified carpal-ulnar distance ratio was preserved and none of the patients developed ulnar translocation of the carpal bones. Radiological union was achieved in all patients. CONCLUSIONS: Scapho-luno-capitate fusion with partial lunate excision and preservation of the proximal lunate surface is a valuable option for treating stage IIIA Kienböck's disease, with satisfactory outcomes. Level of evidence Level IV. Trial registration Not applicable.

Mid-term follow-up results of gradual capitate lengthening for the treatment of stage IIIA Kienbock's disease.

PURPOSE: This study aimed to evaluate the mid-term radiological and clinical results of gradual lengthening of capitate for the treatment of stage IIIA Kienbock's disease. METHODS: We retrospectively reviewed nine patients (five females, four males) with Lichtman stage IIIA Kienbock's disease who underwent gradual capitate lengthening at our hospital. Their clinical (range of motion (ROM), grip strength, visual analogue scale (VAS) value for pain, and Mayo wrist score (MWS)) and radiological outcomes (in terms of progression of arthritis and carpal height ratio) at the last follow-up were compared to the preoperative values. RESULTS: The mean age of the nine patients was 30 years (range: 20-38 years). The mean follow-up period was 73.8 (60-83) months. The average grip strength increased from 14.3 kg preoperatively to 22.3 kg at the last follow-up. The mean MWS increased from 58.8 preoperatively to 79.4 postoperatively. The mean VAS values decreased from the preoperative values: from 1.9 to 0.36 at rest, from 3.75 to 1.6 during mild effort, and from 5.35 to 3 during severe effort. The average carpal height ratio changed from 0.38 preoperatively to 0.53 postoperatively. None of the patients had any arthritic changes in their wrists. CONCLUSION: Gradual lengthening of capitate offers satisfactory mid-term results for treating stage IIIA Kienbock's disease.

Comparing the Radiologic and Functional Outcome of Radial Shortening Versus Capitate Shortening in Management of Kienböck's Disease.

BACKGROUND: Kienböck's disease is the avascular necrosis of the lunate bone. There is no consensus on the treatment strategy to avoid joint deterioration. This trial is conducted to compare the functional and radiological outcomes of radial shortening and capitate shortening techniques, in patients with avascular necrosis of lunate. METHODS: Patients with a confirmed diagnosis of Kienböck's disease who met the inclusion criteria were randomly divided into radial shortening and capitate shortening groups and treated by allocated technique. Physical examination and radiologic evaluations were performed before and 6 and 12 months after the operation. RESULTS: A total of 52 patients (52 wrists) of stage II or III Kienböck's disease were assessed for eligibility, 12 patients in the radial shortening group, and 17 patients remained until the end of the study. Patients in both groups achieved a satisfactory outcome, with no report of postoperative complications. None of the outcome measures, ranges of motion, grip, and pinch strengths were significantly different between the groups. The outcome was not considerably different in patients with positive or negative ulnar variances who were treated by capitate shortening technique. CONCLUSIONS: The capitate shortening technique which is performed through a smaller incision, and takes less time as compared with radial shortening can be advantageous for patients with stage II or III Kienböck's disease regardless of the ulnar variance. This method can be as effective as classical methods such as radial shortening in improving clinical and functional symptoms after surgery while causing fewer complications.

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

PURPOSE: We examined morphologic similarities of the medial lateral femoral trochlea (MFT) and lateral femoral trochlea (LFT) osteochondral flaps for reconstruction of the proximal capitate. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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. CLINICAL RELEVANCE: 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.

Comparison of the early-term clinical results of capitate forage procedure and radial shortening osteotomy in Stage 3A Kienböck's disease.

OBJECTIVES: This study aims to evaluate the efficacy of an alternative method by comparing an old established method with a new less invasive method in the surgical treatment of Stage 3A Kienböck's disease. PATIENTS AND METHODS: Between January 2014 and July 2018, a total of 35 patients (28 males, 7 females; mean age: 22.8±3.3 years; range, 17 to 29 years) who underwent surgery due to Kienböck's disease were retrospectively analyzed. The patients were divided into two groups according to the procedure applied as the capitate forage procedure (CFP) group (Group 1, n=16) and the radial shortening osteotomy (RSO) group (Group 2, n=19). Patients with a minimum follow-up period of 18 months were examined according to the MAYO wrist scores pre- and postoperatively. RESULTS: The postoperative MAYO scores were statistically significantly higher in both groups (CFP, p=0.001; RSO, p=0.000). However, the osteotomy group showed statistically significantly higher results than the forage group in terms of not only postoperative scores, but also pre- and postoperative score difference (p=0.004). CONCLUSION: Our study results confirm that both CFP and RSO are effective in the treatment of Stage 3A Kienböck's disease. However, RSO should be the first choice in Stage 3A patients with high success rates. Supported by long-term follow-up results, CFP may be considered a minimally invasive alternative only in selected patients who avoid major surgery or expect a rapid return to work.

Joint-sparing arthroscopic management of avascular necrosis of the capitate.

Avascular necrosis of the proximal pole of the capitate is an exceedingly rare pathology with few therapeutic solutions. The largest published series concerned a cohort of 6 cases over 10 years. The present case concerns our experience with avascular necrosis of the capitate in a 20-year-old woman. Due to her age and high functional demand, we opted for a minimally invasive solution using arthroscopy. We performed an X-shaped palmaris longus tendon interposition arthroplasty at the midcarpal joint between the capitate and the lunate. We here report 2 years' follow-up.

Bone Morphology in Ulnar Impaction Syndrome: A Radiographic Evaluation.

Background: Positive ulnar variance (UV) may be associated with a higher incidence of ulnar impaction syndrome (UIS). However, neutral and/or negative UV has also been associated with the development of UIS; therefore, other risk factors may be involved. The purpose of this study was to compare radiological bone morphology in patients with UIS and asymptomatic controls. Methods: Between 2009 and 2018, posteroanterior wrist radiographs of 47 wrists in 45 patients diagnosed with UIS were compared with those of 163 wrists in 93 asymptomatic patients from the control group. The following parameters were obtained: ulnar variance (UV); ulnar head top-fovea distance (UTFD); capitate-triquetrum distance (CTD); radio-lunate distance (RLD) and lunate coverage ratio (LCR). The morphology of the lunate was classified based on the absence (type I) or presence (type II) of a medial facet that articulates with the hamate. The radiographic parameters and lunate types were compared between the two groups. We then divided the groups into two subgroups: the positive UV subgroup and the neutral/negative UV subgroup. In each subgroup, the radiographic parameters and lunate types were compared between the UIS and control groups. Results: In the UIS group, the UV and UTFD were significantly increased compared to those in the control group. The proportion of type II lunates was significantly higher in the UIS group than in the control group. In addition, the type II lunate was more common in the UIS group in both the positive UV and negative UV groups. Conclusions: Our study suggests that in addition to positive UV, ulnar head morphology with an increased UTFD and type II lunate morphology may be associated with the development of ulnar impaction syndrome. Level of Evidence: Level III (Diagnostic).

Resurfacing capitate pyrocarbon implant as salvage procedure in several serious outcomes of carpal injuries. Clinical experience and follow-up.

BACKGROUND AND AIM: Resurfacing Capitate Pyrocarbon Implant has been introduced in the surgical practice as an alternative method to restore wrist motion, strength and functions in patients suffering from wrist osteoarthritis. It has already been well described in the literature as a treatment for advanced stages of degenerative wrist diseases which follow scaphoid's and lunate's injuries such as scapho-lunate advanced collapse, scaphoid non-union advanced collapse, and advanced stages of Kienböck disease. Authors extended the use of RCPI to other selected cases of complicated wrist injuries, spreading out from the classic indications for which this device was designed. METHODS: We discuss 8 cases with serious outcomes of carpal injuries treated with Resurfacing Capitate Pyrocarbon Implant as salvage procedure between 2005 and 2013 by the first author of this paper Results: Among the eight particular selected cases, at a mean 4.3 years follow-up (range 2-11) only one was considered a failure and underwent a total wrist arthrodesis, resolving pain after all. The seven other cases reported good results. Range of Motion, Visual Analogue Scale for pain, subjective satisfaction and radiographical outcomes are reported. CONCLUSIONS: As a result of this heterogeneous clinical experience, validated by long-term follow-ups in most cases, we think that the use of a Resurfacing Capitate Pyrocarbon Implant can be suggested as an option in the outcomes of various carpal injuries.

Order of importance of anatomical risk factors in Kienböck's disease: An artificial neural network study.

Anatomical variations in bony structures around the wrist have been considered as risk factors for Kienböck's disease: ulnar variance, Nattrass index, ulnar variance/capitate height ratio and presence of a lunohamate joint. This study aimed to assess the order of importance of these variations as risk factors for Kienböck's disease. Two groups were formed: patients (n = 58) and controls (n = 235). On posteroanterior radiographs in the two groups, these risk factors were examined by four raters. After inter-rater correlation analysis, an artificial neural network was used to estimate their relative importance. All parameters showed statistically significant inter-rater correlation (p < 0.05). The artificial neural network study showed that the three most important risk factors, in descending order, were: Nattrass index, ulnar variance/capitate height ratio and negative ulnar variance. The study determined the order of importance of the anatomical risk factors for Kienböck's disease measurable on posteroanterior wrist radiographs. Although these findings seem to be useful in the diagnostic algorithm of Kienböck's disease, multivariate analysis of all measurable risk factors is still needed. The artificial neural network approach could contribute to such a comprehensive study.

Atraumatic Index Finger Flexor Tendon Rupture as a Presenting Sign of Capitate Osteonecrosis: A Report of 2 Cases.

CASE: We present 2 cases of spontaneous index finger (IF) flexor tendon ruptures because of previously undiagnosed osteonecrosis (OA) of the capitate. Imaging revealed fragmentation of the capitate, and patients were treated with excision or fixation of the bony fragments with tendon repair. At the final follow-up, both patients had functional digital range of motion. CONCLUSIONS: OA of the capitate is relatively rare and may present as atraumatic (IF) flexor tendon ruptures because of attritional wear when associated with bony fragmentation.

How Much Scaphoid Can be Safely Resected? A Biomechanical Analysis of the Effects of Distal Scaphoid Resection.

BACKGROUND: Resection of the distal pole of the scaphoid has been advocated as a simple alternative to other wrist salvage procedures for scaphoid nonunion advanced collapse and scaphotrapezio-trapezoid arthritis. However, the extent of scaphoid that may be resected without adversely affecting carpal kinematics has never been clearly defined. METHODS: Seven cadaveric upper extremities were tested in a custom motion wrist simulator. A 3-stage sequential sectioning of the distal scaphoid protocol was performed in 25% increments then cyclic active wrist flexion-extension and dart thrower's motion trials were recorded. RESULTS: The extent of distal scaphoid resection had no effect on overall wrist range of motion. The lunate assumed a more extended position following resection of the distal scaphoid compared to intact. At 25%, 50%, and 75% of distal scaphoid resection, the lunate extended to 13.32° ± 9.4°, 23.43° ± 7.5°, and 15.81° ± 16.9°, respectively. The capitate migrated proximally with 25% and 50% distal scaphoidectomy, and proximally and radially with 75% of the scaphoid resected. Resection of 75% of the scaphoid resulted in unstable wrist kinematics. CONCLUSIONS: Resection of up to 25% of the distal scaphoid did not significantly influence carpal kinematics and induced mild lunate extension deformity. Resection of 50% of the scaphoid induced further and potentially clinically significant lunate extension and dorsal intercalated segment instability. Further removal of 75% of the distal scaphoid induced capitate migration radially and unpredictable wrist kinematics. Consequently, removal of over 25% of the scaphoid should be avoided or supplemented with partial wrist fusion.