Evaluation of a cadaveric wrist motion simulator using marker-based X-ray reconstruction of moving morphology.

Surgical intervention is a common option for the treatment of wrist joint arthritis and traumatic wrist injury. Whether this surgery is arthrodesis or a motion preserving procedure such as arthroplasty, wrist joint biomechanics are inevitably altered. To evaluate effects of surgery on parameters such as range of motion, efficiency and carpal kinematics, repeatable and controlled motion of cadaveric specimens is required. This study describes the development of a device that enables cadaveric wrist motion to be simulated before and after motion preserving surgery in a highly controlled manner. The simulator achieves joint motion through the application of predetermined displacements to the five major tendons of the wrist, and records tendon forces. A pilot experiment using six wrists aimed to evaluate its accuracy and reproducibility. Biplanar X-ray videoradiography (BPVR) and X-Ray Reconstruction of Moving Morphology (XROMM) were used to measure overall wrist angles before and after total wrist arthroplasty. The simulator was able to produce flexion, extension, radioulnar deviation, dart thrower's motion and circumduction within previously reported functional ranges of motion. Pre- and post-surgical wrist angles did not significantly differ. Intra-specimen motion trials were repeatable; root mean square errors between individual trials and average wrist angle and tendon force profiles were below 1° and 2 N respectively. Inter-specimen variation was higher, likely due to anatomical variation and lack of wrist position feedback. In conclusion, combining repeatable intra-specimen cadaveric motion simulation with BPVR and XROMM can be used to determine potential effects of motion preserving surgeries on wrist range of motion and biomechanics.

Safe zones in dorsal portals for wrist arthroscopy: a cadaveric study.

The standard dorsal portals are the most commonly used in wrist arthroscopy. This cadaveric study aims to determine safe zones, by quantitatively describing the neurovascular relationships of the dorsal wrist arthroscopy portals: 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar. The neurovascular structures of twenty-one fresh frozen human cadaveric upper limbs were exposed, while the aforementioned portals were established with needles through portal sites. The minimum distance between portals and: dorsal carpal branch of radial artery, superficial branch of radial nerve, posterior interosseous nerve and dorsal branch of ulnar nerve, were measured accordingly with a digital caliper, followed by statistical analysis of the data. The median and interquartile range for each portal to structures at risk were determined and a safe zone around each portal was established. Free of any neurovascular structure safe zones surrounding 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals were found at 0.46mm, 2.33mm, 10.73mm, 11.01mm, 10.38mm, 5.95mm and 0.64mm respectively. Results of statistical analysis from comparisons between 1-2, 3-4 and midcarpal radial portals, indicated that 1-2 was the least safe. The same analysis among 3-4, midcarpal radial, midcarpal ulnar and 4-5 portals indicated that midcarpal portals were safer, while 3-4 was the least safe. Results among midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals indicated that 6-radial and specifically 6-ulnar were the least safe. This study provides a safe approach to the dorsal aspect of the wrist, enhancing established measurements and further examining safety of the posterior interosseous nerve.

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.

Analysis of Wrist Morphology Through Hamate and Lunate Bone Variations in Anatolian Population Using Plain Radiography / Análisis de la Morfología de la Articulación Radiocarpiana a Través de las Variaciones de los Huesos Hamato y Semilunar en la Población de Anatolia Mediante Radiografía Simple

SUMMARY: The present study aimed to evaluate wrist (lunate) anatomy in terms of the incidence of lunatum morphology on plain-radiographs among the Anatolian (Turkey) population, accompanied by demographic analysis. We obtained all the patients' data regarding demographical features, diagnosis, and posteroanterior (PA) X-ray imaging. Two radiograph-reviewers repeated the analysis twice, one month later, blinded to their findings before the previous review. The lunatum structure was determined as Type-1 (n:293) and Type-2 (n:207) for each radiograph. Most of the 500 wrists' radiographs [n:293 (58.6 %)] were type-I lunate. The mean age was 36.7±13.3 (range:18-90) years. Sex distribution was as follows: 185 (63.1 %) males to 108 (36.9 %) females. Type-2 lunate was seen in 207 participants (41.4 %). The mean age for type-2 was 41.6±15.2 (18-88) years. 142 (68.6 %) participants were male sex, while 65 (31.4 %) were females. The mean age of subjects with type-I showed a difference with type-II (p=0.007). There was no relationship in terms of sex (p=0.206) between the groups. In the Anatolian region, type-1 lunate was dominant compared to type-2. The incidence rate of lunate type in Anatolian population was similar to the Arab population.

El presente estudio tuvo como objetivo evaluar la anatomía de la articulación radiocarpiana en términos de la incidencia de la morfología del hueso semilunar en radiografías simples entre la población de Anatolia (Turquía), acompañado de un análisis demográfico. Obtuvimos todos los datos de los pacientes con respecto a las características demográficas, el diagnóstico y las imágenes de rayos X posteroanteriores (PA). Dos revisores de radiografías repitieron el análisis dos veces, un mes después, sin conocer sus hallazgos antes de la revisión anterior. La estructura del lunatum se determinó como Tipo-1 (n:293) y Tipo-2 (n:207) para cada radiografía. La mayoría de las 500 radiografías de muñecas [n:293 (58,6 %)] fueron semilunar tipo I. La edad media fue de 36,7±13,3 (rango: 18-90) años. La distribución por sexos fue la siguiente: 185 (63,1 %) hombres y 108 (36,9 %) mujeres. El semilunar tipo 2 se observó en 207 participantes (41,4 %). La edad media para el tipo 2 fue de 41,6±15,2 (18-88) años. 142 (68,6 %) participantes eran del sexo masculino, mientras que 65 (31,4 %) eran del sexo femenino. La edad media de los sujetos con tipo I mostró una diferencia con el tipo II (p = 0,007). No hubo relación en cuanto al sexo (p=0,206) entre los grupos. En la región de Anatolia, el semilunar tipo 1 era dominante en comparación con el tipo 2. La tasa de incidencia del tipo semilunar en la población de Anatolia fue similar a la de la población árabe.

A study of clinical anatomy of the safe zone for the volar approach for wrist arthroscopy.

OBJECTIVE: The current study was to perform an anatomical observation of the volar approach for wrist arthroscopy and to establish the safe zone for this approach. METHODS: Eight preserved specimens and 2 fresh specimens were used to simulate the medial-to-lateral operation and to mark the volar approach. Based on anatomical measurements of the volar approach, the closest distances from the 1/2, 6R, 6U, VR, VR' and VU approaches to the adjacent important structures were established. RESULTS: The closest distance from the 1/2 approach to the superficial branch of the radial nerve was 2.4±1.5mm. The closest distances from the 6U and 6R approaches to the dorsal carpal branch of the ulnar nerve were 16.2±1.3mm and 9.0±2.4mm, respectively. The closest distances from the VR and VR' approaches to the palmar cutaneous branch of the median nerve were 6.7±1.1mm and 2.8±0.9mm, respectively; the closest distances to the radial artery were 6.3±4.0mm and 10.0±3.4mm, respectively. Moreover, both of the two approaches passed through the base of the flexor carpi radialis tendon. The closest distance from the VU approach to the ulnar artery and flexor digitorum profundus tendon were 3.3±1.4mm and 0.3±2.5mm, respectively. CONCLUSIONS: In conclusion, a safe zone could be located for the establishment of the volar approach for wrist arthroscopy. LEVEL OF EVIDENCE: III; retrospective study with no control group.

The distance between the distal margin of the flexor retinaculum and the radiocarpal joint as a landmark in CTS surgery: A cadaver study.

BACKGROUND: The most frequent peripheral entrapment neuropathy is compression of the median nerve in the carpal tunnel, known as carpal tunnel syndrome. The most effective treatment is surgery, where the flexor retinaculum (FR) is divided. Nevertheless, after this operation, a significant number of patients suffer from persistent symptoms due to incomplete FR distal release. It may be difficult to identify the distal boundary of the FR due to the minimal skin incision. We aimed to identify an anatomical landmark to avoid incomplete distal FR release. The radiocarpal (RC) joint can be palpated, and lies in close proximity to the boundaries of the FR. Thus, the distance between the RC joint space and the distal FR margin - the RC-FR distance - could be a reliable and individual morphologic measurement from easily acquired regional anthropological measurements. METHODS: During this study, 39 radiocarpal regions of 23 embalmed cadavers were dissected, and measurements were taken. Linear regression corresponding to the ulnar length and the RC-FR distance was established. RESULTS: The mean RC-FR distance from the RC joint space to the distal FR margin was 3.8 cm (95 % CI 3.5-4.0), and the range was 2.3-5.1 cm. This distance was 1.1 cm (95 % CI 0.8-1.4) longer in males than in females (p < 0.00001), and there were no side-specific differences. The individual projection of the distal FR margin in centimeters can be calculated by measurement of the ipsilateral ulnar length divided by 4 and reduced by 2.9, p < 0.005. CONCLUSIONS: The side-equal and sex-specific position of the distal flexor retinaculum margin could be calculated from the palpable radiocarpal joint space based on the ipsilateral ulnar length.

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).

An Anatomical Study of the Palmaris Brevis, Transverse Carpal Ligament, and the Recurrent Motor Branch of the Median Nerve.

Background: The anatomical structures in relation to the carpal tunnel release are the palmaris brevis muscle (PBM), transverse carpal ligament (TCL), and the recurrent motor branch of the median nerve (RMBMN). Our aim is to describe the gross morphology in the Korean population of the PBM, TCL, and RMBMN specifically looking for anomalies, and to determine the muscles encountered during a standard carpal tunnel release. Material and Methods: A total of 30 cadaveric hands were dissected. A longitudinal line drawn from the third web space to the midpoint of the distal wrist crease served as the reference line (RL). The PBM and TCL were classified according to its shape and location. The length, width, and thickness of the TCL were measured. The ratio of the lengths of PBM and TCL to RL was calculated. The course of the RMBMN was dissected specifically looking for anomalies. We also looked at the muscle fibers encountered during a standard carpal tunnel release to identify the muscle. Results: PBM was classified into three different types based on the shape. The average thickness of the PBM and TCL were 0.89 ± 0.16 mm and 1.43 ± 0.40 mm, respectively. The distal border of the TCL was thicker than the proximal border. The average ratio of the length of the PBM to the RL was 25.65 ± 8.62% and TCL to the RL was 24.00 ± 3.37%. The distribution of the RMBMN was classified into three different types. A few accessory branches of the RMBMN were also noted. And 36 muscle fibers were noted within the TCL in line with the RL. Conclusion: We clarified findings and added quantitative information about the anatomical structures surrounding carpal tunnel. A thorough knowledge of the anatomy and anomalies around the carpal tunnel is helpful for surgeons to ensure optimal surgical results.

Ulnar-Sided Wrist Pain in the Athlete: Sport-Specific Demands, Clinical Presentation, and Management Options.

ABSTRACT: Ulnar-sided wrist injuries are common in sports that require repeated pronosupination, wrist radial/ulnar deviation, axial loading, and gripping equipment. Common anatomic structures affected include the triangular fibrocartilage complex, extensor carpi ulnaris tendon, distal radioulnar and ulnocarpal joints, and hamate bone. Presenting symptoms include pain with activity, swelling, possible snapping or clicking, and reproduction of symptoms with provocative maneuvers. Imaging may confirm or rule out pathologies, but abnormal findings also may present in asymptomatic athletes. Initial treatment is usually nonoperative with splinting, load management, activity modification, strengthening the components of the kinetic chain of the particular sport, and pain management. Surgery is usually indicated in ulnar-wrist pain pathology such as hook of hamate fractures and required in associated instability. Future research should address specific treatment and rehabilitation protocols, emphasizing the complete kinetic chain along with the injured wrist.

Examination of the Wrist.

LEARNING OBJECTIVES: After reading this article and reviewing the supplemental videos, the participant should be able to: 1. Identify common wrist conditions that may be encountered on evaluation. 2. Describe provocative maneuvers used to confirm a diagnosis of wrist disorder. 3. Develop a systematic approach to examination of the wrist. 4. Determine appropriate diagnostic maneuvers for radial, central, and ulnar wrist pain. SUMMARY: The wrist is a complex structure, and providers caring for hand and upper extremity conditions need to have an understanding of the wrist examination and provocative maneuvers for conditions that are encountered. Fractures, tendonitis, arthritis, and instabilities are all commonly encountered, and the provider should have an idea of the diagnosis based on clinical examination and use imaging as needed to confirm or stage a diagnosis.

Five Wrist Operations That Give the Best Results.

LEARNING OBJECTIVES: After reading this article and viewing the videos, the participant should be able to: 1. Recognize the following five wrist operations as consistent options for different wrist injuries: carpal tunnel release, medial femoral condyle bone flap for scaphoid nonunion associated with carpal collapse and avascular necrosis, scaphocapitate arthrodesis for Kienböck disease, percutaneous screw fixation of nondisplaced scaphoid fracture, and four-corner arthrodesis. 2. Know the state-of-the-art of these five procedures. 3. State the indications of each operation. 4. List the surgical steps of these five procedures. SUMMARY: The wrist is a complex joint that concentrates different types of tissues (e.g., bone, cartilage, ligaments, nerves, vessels) and a broad different spectrum of diseases. Treatment of wrist injuries has improved during recent years, mainly because of improvement in strategy, techniques, microsurgical equipment, understanding anatomy and improvements in technology. In this article, we present the five operations (i.e., carpal tunnel release, medial femoral condyle bone flap for scaphoid nonunion associated with carpal collapse and avascular necrosis, scaphocapitate arthrodesis for Kienböck disease, percutaneous screw fixation of nondisplaced scaphoid fracture, and four-corner arthrodesis) that have consistently given good outcomes in patients suffering from different wrist injuries/maladies.

Imaging study of coronal structural matching of the distal radius in normal adults.

BACKGROUND: As an important anatomical basis, coronal structural position matching of the distal radius has long been lacking in terms of a quantitative understanding, and such matching is correlated with the postoperative functional recovery of patients with distal radius fracture. The purpose of this study was to explore the degree of coronal structural matching of the distal radius in a normal population and to improve the detailed anatomical knowledge of the distal radius. METHODS: The reconstructed 3D data were analysed using 3-matic research software from thin-film CT images of 80 normal adults, and the coronal structural matching of the distal radius was studied from two aspects: 1) self-matching of the distal radius; and 2) matching between the distal radius and ulna (i.e., the joint space of the distal radioulnar joint). Specific research methods: 1) The relative position of the medial wall of the distal radius with respect to the lunate was determined as the percentage (%) of the vertical distance from the medial wall of the radius to the most prominent ulnar point of the lunate in the corresponding plane from the ulna to the radius. 2) A total of 9 sets of data were collected for evaluating the palmar lateral spacing, median spacing, and dorsal lateral spacing at the distal, middle, and proximal levels of the radius. RESULTS: In the study, 9 sets of data were obtained. And the data of self-matching of the coronal structural of distal radius was also obtained, was 45.0% ± 16.2%. The P values in the above data were all greater than 0.05, showing no statistical significance. Finally, data of coronal bone structural matching of distal radius in 80 normal adults were obtained. CONCLUSIONS: Our study refines the anatomical data of the degree of coronal bone structural matching of the distal radius in a normal population. To explore the relationship between coronal alignment and function in cases of distal radius fracture, a standardized approach was established. Thin- film CT may help diagnose patients with dysplasia around the lunate and radioulnar joint that is difficult to diagnose on MRI.

Wrist Arthroscopy Scope for the Best and Plan for the Worst.

Wrist arthroscopy is a useful surgical technique that has been steadily gaining popularity since the 1980s. In addition to being a valuable diagnostic tool, wrist arthroscopy can be used for an expanding array of therapeutic interventions and is an attractive, minimally invasive treatment modality for patients. However, wrist arthroscopy is not without its complications, and a detailed understanding of the relevant anatomy, instrumentation, and methodology is critical for success.

Safe zones in volar portals for wrist arthroscopy, evaluation of central portal : a cadaveric study.

The purpose of this cadaveric study is to determine safe zones utilizing volar portals for wrist arthroscopy, by quantitatively describing the neurovascular relationships of a volar radial and a volar ulnar wrist arthroscopy portals in comparison with those of a newly described volar central portal (7) , considering the advantages in visualization of volar portals for wrist arthroscopy over the standard dorsal (19) . The neurovascular structures and the tendons of nine frozen human cadaveric upper limbs were exposed, while the aforementioned volar portal sites were pointed out with pins. The horizontal distance between the portals and the closest neurovascular branch or tendon was measured with a digital caliper, followed by statistical analysis of the data. The median interquartile range distances from portals to structures at risk were measured and safe zones around each portal were established. This study provides a safe approach to the volar radial and ulnar aspects of the radiocarpal and midcarpal joints, while volar radial and ulnar portals should be considered for inclusion in the arthroscopic examination of any patient with radial and ulnar sided wrist pain respectively (17,18) . Regarding the volar central portal, it is reproducible, safe and both the above joints can be inspected through one single incision (7) .

Image-Based Comparison Between the Bilateral Symmetry of the Distal Radii Through Established Measures.

PURPOSE: Anthropometric assessment of bony structures in the body is important for preoperative computer-aided surgery, implant design, finite element modeling, and biomechanical studies investigating joint structure and function. The use of the contralateral limb in surgery and clinical practice relies on the assumption that the right and left limbs of an individual are symmetric. Therefore, the purpose of this study was to quantify the bilateral symmetry of the bony structures of the distal radius using 3-dimensional (3D) computed tomography. METHODS: We collected computed tomography images of 37 paired, fresh-frozen, healthy cadaveric male upper limbs (aged 75.4 ± 8.3 years). Three-dimensional reconstructed models were created using semiautomatic segmentation. Using the 3D models, we measured 3D radial inclination, 3D volar tilt, 3D radial height, medial volar cortical angle, middle volar cortical angle, and lateral volar cortical angle and compared them between sides. RESULTS: There were no statistically significant differences measured between right and left distal radius in 37 paired wrists. Mean radial height was 12.81 mm (SD, 1.74 mm) on the left and 12.88 mm (SD, 1.72 mm) on the right. Mean volar tilt was 10.74° (SD, 3.74°) and 10.77° (SD, 3.19°) and radial inclination was 24.05° (SD, 2.63°) and 24.18° (SD, 3.41°) on the left and right, respectively. Mean volar cortical angle across the radius was 140.9° (SD, 7.9°) on the left and 140.1° (SD, 7.9°) on the right. CONCLUSIONS: Direct bilateral comparison of the distal radius and wrist joints is useful to predict normal anatomy of the injured radius, because bilateral similarities exist. CLINICAL RELEVANCE: This article provides a comprehensive list of measurements of the distal radius compared bilaterally using a 3D model. From this study, we found that the contralateral radius can be used as a benchmark with which to compare fracture reduction and to manage malunions during the preoperative planning of corrective osteotomies. It can also be used to define normal anatomy.

Volar Midcarpal Portals in Wrist Arthroscopy.

PURPOSE: To describe the placement of volar midcarpal portals using the inside-out technique, and the surrounding anatomical structures at risk. METHODS: Five fresh-frozen cadavers were used. Volar ulnar midcarpal (VUMC) and volar radial midcarpal (VRMC) portals were placed using an inside-out technique. The distance between these portals to surrounding anatomical structures was measured in millimeters using a caliper. RESULTS: The VUMC portal pierced the flexor digitorum profundus tendon to the middle finger in 1 specimen. The portal was an average 3.7 and 8.4 mm away from the ulnar artery and nerve, respectively. The VRMC portal pierced the palmaris longus in 2 specimens. It usually was between the flexor pollicis longus, the palmaris longus, and the median nerve. It was an average of 1.0 and 1.95 mm away from the median nerve and palmar cutaneous branch of the median nerve, respectively and in 1 specimen, was in contact with the median nerve after piercing the mesoneurium. CONCLUSIONS: With increasing use of volar midcarpal arthroscopy, the surgeon needs to have an understanding of the structures at risk when placing the VUMC and VRMC portals. CLINICAL RELEVANCE: When developing the volar midcarpal portals, the surgeon needs to pay close attention to the anatomical structures at risk and, in particular, the median nerve from the VRMC portal.

An Extensile Approach to the Radial Aspect of the Carpus: "The Link Incision".

The structures on the radial side of the wrist and thumb base can be approached by a longitudinal incision on the radial side of the wrist. However, longer longitudinal scars can be cosmetically unacceptable and can result in a scar contracture. It is preferable to curve longer incisions along the Langer's skin lines to achieve better scar characteristics. Curving the incision also enables an extensile approach and provides easy access to the thumb base, radial carpus, and radial wrist joint. We describe our approach as a "Link" between the most common approaches that surgeons are familiar with; the dorsoulnar approach to the thumb metacarpophalangeal joint for ulnar collateral ligament repair and the flexor carpi radialis approach for distal radial fracture fixation. The zone between these two incisions is not as frequently approached. Our incision connects these two well established incisions and we have described a step by step approach to this unfamiliar area. This "Link zone" overlies the thumb trapeziometacarpal joint, scaphotrapeziotrapezoid joint, and the radial styloid. It contains superficial branches of the radial nerve, first extensor compartment tendons, and the deep branch of radial artery in the anatomic snuff box. The "Link incision" is an extensile approach in both the proximal and distal directions.

Normal values of distal radioulnar translation assessed by three-dimensional C-arm scans: a cadaveric study.

We investigated whether mobile C-arm cone beam computer tomography (CBCT) could be used to measure radioulnar translation. The study was conducted on 31 Thiel-fixed intact cadaver arms. Three-dimensional scans of each wrist were carried out in pronation and supination. Four established measurement methods were used (radioulnar line, subluxation ratio, epicentre and radioulnar ratio methods) to measure radioulnar translation. The intraclass correlation coefficient for inter-observer and intra-observer reliability were excellent in three of four methods (>0.94). The reference ranges for physiological radioulnar translation were between -30% and 91% (radioulnar line method), -32% and 87% (subluxation ratio method), -40% and 23% (epicentre method), and 2% and 73% (radioulnar ratio method). Our results indicate that radioulnar translation in the distal radioulnar joint can be determined reliably using mobile C-arm CBCT. The normal values provide a basis for further experimental and clinical studies.

An Anthropometric Assessment of the Proximal Hamate Autograft for Scaphoid Proximal Pole Reconstruction.

PURPOSE: Fragmentation of the scaphoid proximal pole secondary to avascular necrosis presents a difficult reconstructive problem. This anthropometric study assesses the utility of the ipsilateral proximal hamate for complete osteochondral scaphoid proximal pole reconstruction. METHODS: Twenty-nine cadaveric specimens underwent computed tomography scanning and 3-dimensional reconstruction of the carpus and distal radius. Scaphoid height was measured and a third of its height was used to simulate resection of the proximal scaphoid pole and extent of hamate autograft required. The proximal scaphoid and hamate were divided into 6 sections, and compared using an iterative point-to-point distance algorithm. Average distance between the scaphoid and the hamate surfaces was determined. An interbone algorithm was used to assess radioscaphoid joint congruency and articular contact surface of the native scaphoid compared with the scaphoid reconstructed with hamate autograft. RESULTS: The mean height of scaphoid proximal pole excision and proximal hamate autograft height was 9.3 mm. Comparing the morphology of the native scaphoid and hamate autografts, the absolute distances were the largest in the volar radioscaphoid, dorsal radioscaphoid, and dorsal scaphocapitate segments. Without osteotomy, the hamate autograft may cause impaction in the dorsal-radial aspect of the distal radius. The hamate autograft also shifted the articular contact point of the radioscaphoid joint toward the dorsal-radial position. Nine hamate autografts were classified as poor-fitting. Poor-fitting specimens had a greater radial styloid to distal radioulnar joint distance. These specimens also had wider hamates and scaphoids in the radial-ulnar dimension and wider scaphoids in the volar-dorsal dimension. Lunate type did not correspond to anthropometric fit. CONCLUSIONS: The proximal hamate osteochondral graft was poor fitting in 31% of cases (9 of 29 specimens). Wrists with radial-ulnar hamate width less than 10 mm, radial-ulnar scaphoid width less than 10 mm, and volar-dorsal scaphoid width less than 16 mm demonstrate better anthropometric fit. CLINICAL RELEVANCE: This study provides an anthropometric assessment of the recently described proximal hamate autograft, a new bone graft option for proximal scaphoid pole reconstruction.

Distal radius fluoroscopic skyline view: extension-supination versus flexion-supination.

The aim of our study was to compare the vertical fluoroscopic view of the wrist in extension and supination (ES) to the view in flexion and supination (FS) and determine which of the two views allowed the best visualization of four selected anatomical landmarks SDLR (radial styloid, dorsal radius cortex, Lister's tubercle and distal radioulnar joint). Our case series included 50 patients who had suffered a distal radius fracture and undergone an open reduction and internal fixation procedure with a volar locking plate. For each case, two fluoroscopic views were taken: ES (wrist extension and supination) (group I) and FS (wrist flexion and supination) (group II). Ten observers had to recognize the SDLR anatomical landmarks on 100 fluoroscopic skyline views (time 1) and 15 days later (time 2). The rate of recognition of the four anatomical landmarks was 78% in group I and 66% in group II (p < 0.001). The concordance rate of recognition of the four anatomical landmarks was mediocre (κ = 0.411). In conclusion, the vertical fluoroscopic skyline view in wrist extension and supination seems to be the most adequate view to assess the quality of the fracture reduction, the distal radioulnar joint and the length of the screws in open reduction and internal fixation of distal radius fractures with volar locking plates.