CT Scan versus Saline Load Test for Detection of Traumatic Wrist Arthrotomy

Background Traumatic arthrotomy of the wrist is most commonly detected using the saline load test (SLT); however, little data exists on the effectiveness of the SLT to this specific joint. The use of computed tomography (CT) scan has been validated as an alternative method to detect traumatic arthrotomy of the knee, as the presence of intra-articular air can be seen when there is violation of the joint capsule. Question/Purpose The purpose of this study was to determine the ability of CT scan to identify arthrotomy of the wrist capsule and compare the diagnostic performance of CT versus traditional SLT. Materials and Methods Ten fresh frozen cadavers which had undergone transhumeral amputation were initially used in this study. A baseline CT scan was performed to ensure no intra-articular air existed prior to intervention. After baseline CT, an arthrotomy was created at the 6R radiocarpal portal site. The wrists then underwent a postarthrotomy CT to identify the presence or absence of intra-articular air. Following CT, the wrists were subjected to the SLT to detect the presence of extravasation from the arthrotomy. Results Nine cadavers were included following baseline CT scan. Following arthrotomy, intra-articular air was visualized in eight of the nine cadavers in the postarthrotomy CT scan. Air was seen in the radiocarpal joint in eight of the nine wrists; midcarpal joint in seven of the nine wrists; and distal radioulnar joint in six of the nine wrists. All wrists (nine of the nine) demonstrated extravasation during the SLT. The mean volume of extravasation occurred at 3.7 mL (standard deviation = 2.6 mL), with a range of 1 to 7 mL. Conclusion CT scan correctly identified eight of the nine simulated traumatic arthrotomies. Injection of 7 mL during the SLT was necessary to identify 100% of the arthrotomies. Clinical Relevance CT scan is a sensitive modality for detection of traumatic arthrotomy of the wrist in a cadaveric model.

A Preliminary Model of the Wrist Midcarpal Joint

Background A challenge to deciphering the effect of structure on function in the wrist involves difficulty in obtaining in-vivo information. To provide a platform to study wrist mechanics using in vivo acquired forces, we developed a model of the midcarpal joint based on computed tomography (CT) scans of normal wrists. Finite element analysis (FEA) can enable application of in vivo collected information to an ex vivo model. Objectives The objectives of this study are to (1) create a three-dimensional model of the midcarpal joint of the wrist based on CT scans and (2) generate separate models for the midcarpal joint based on two distinct wrist types and perform a pilot loading of the model. Methods CT scans from a normal patient database were converted to three-dimensional standard template library (STL) files using OsiriX software. Five type 1 and five type 2 wrists were used for modeling. A simulated load was applied to the carpometacarpal joints in a distal-to-proximal direction, and FEA was used to predict force transfer in the wrist. Results There were 33% type 1 and 67% type 2 wrists. The midcarpal joint dimensional measurements estimated from the model had intermediate agreement between wrist type as measured on CT scan and as predicted by the model: 56% Cohen's kappa (95% confidence interval) = 0.221 (0.05–0.5). Surface stress on the carpometacarpal joints is different in type 1 and type 2 wrists. On loading the neutral wrist, the capitolunate angle was 90 degrees in type 1 wrists and 107 degrees in type 2 wrists (p < 0.0001). Conclusions The model predicted differences in movement and force transfer through the midcarpal joint dependent on structural type. This knowledge can improve our understanding of the development of disparate patterns of degeneration in the wrist.

Synovial Chondromatosis of the Midcarpal Joint: A Case Report and Brief Review of Literature

Objective Synovial chondromatosis is a rare benign proliferative disorder of synovium characterized by the formation of cartilaginous bodies in a joint. The condition typically affects one single large joint. The development of synovial chondromatosis in the joints of hand and wrist is extremely rare. Case description In this report, we present a case of synovial chondromatosis arising from the midcarpal joint and the arthroscopic treatment thereof. Literature review Owing to its rarity, literature on synovial chondromatosis occurring in the hand and wrist is extremely limited. To our knowledge, no report has been published describing the arthroscopic treatment of an isolated synovial chondromatosis of the midcarpal joint. Clinical relevance As synovial chondromatosis of the hand and wrist is extremely rare, and clinical and radiological findings can be nonspecific, the diagnosis might be overlooked initially. The condition does, however, require surgical treatment and thorough follow-up. Thus, awareness of this possible diagnosis among treating physicians is important.

Kinematics of the wrist in Kienböck’s disease: a four-dimensional computed tomography study

We studied the kinematics of 20 wrists affected by Kienböck’s disease using four-dimensional computed tomography (4-D-CT) scanning. Degenerative changes progressed from the lunate facet to the scaphoid fossa at the radiocarpal articulation, then involved the midcarpal joint. Lunate fracture types included coronal (14/20), sagittal (10/20) and ligament attachment-types (8/20). Findings specific to dynamic scanning included the nutcracker phenomenon (12/20), anterior radiolunate impingement (7/20), internal instability of the lunate (6/20), ulnar styloid triquetral impingement (3/20) and dynamic proximal row instability (2/20). Ulnocarpal translocation was found in 4/20 cases. Dynamic 4-D-CT has helped us to identify a subset of pathology in Kienböck’s disease on assessment of static imaging. Better understanding of these phenomena can improve our understanding of symptoms and may help direct surgical treatment. Level of evidence: IV

Capitate and Lunate Morphology in Normal Wrist Radiographs-A Pilot Study

Background: Morphology may provide the basis for the understanding of wrist mechanics. Methods: We used classification systems based on cadaver dissection of lunate and capitate types to evaluate a normal database of 70 wrist radiographs in 35 subjects looking for associations between bone shapes. Kappa statistics and a log-linear mixed -effects model with a random intercept were used. Results: There were 39 type-1, 31 type- 2 lunates, 50 spherical, 10 flat and 10 V-shaped capitates. There was a significant difference in lunate and capitate shape between the hands of the same individual p <0.001. This may be due to different loads on the dominant vs. nondominant hands in the same individual. Conclusion: Further study to better understand the development of radiographic parameters of the midcarpal joint may aid in our understanding of the morphology and mechanics of the wrist.

Translation of 2-Dimensional Wrist Radiographic Measurements to 3-Dimensional CT Scans

Background: Anatomical structure affects function. The morphology of articulations dictates the way forces will travel through the joint. A better understanding of the structure and function of the wrist will enhance our ability to diagnose and treat wrist conditions. Two wrist types have been described based on the morphology of the midcarpal joint. Biomechanically it is important to see if these 2-dimensional (2D) observations reflect articular contact areas. Our purpose was to assess the correlation between measurements performed on wrist radiographs (2D) to measurements performed on 3-dimensional (3D) computed tomography (CT). Methods: Retrospective review of a database of normal wrist radiographs and corresponding normal CT scans. Only imaging pairs with normal carpal alignment and technically optimal imaging were included. Evaluations included lunate, capitate and wrist type, capitate circumference, percent capitate circumference and volume that articulates with the lunate, scapholunate ligament, scaphoid, hamate, trapezoid, base of the index and middle and ring metacarpal bones. Results: Midcarpal joint radiographic measurements were positively correlated with measurements on CT scans. Correlations were 0.51 for capitate type and 0.71 for lunate type with both p < 0.001. Percent contact of the lunate with the hamate: r was 0.74 p < 0.001. Using logistic regression analysis, percent lunate-hamate contact on CT was a significant predictor of radiographic lunate type 2 p < 0.001. Percent contact area between lunate and hamate > 7.8% on CT scan achieved a sensitivity of 100% and specificity 79.4% for a type 2 lunate. Conclusions: 1) Good correlations found between CT and plain radiographs in lunate type, capitate type, and midcarpal joint contact support the use of plain radiographs to describe contact between the carpal bones in the clinical setting. 2) The retrospective nature of this study limited the technical quality of the measurements. Volumetric analysis may aid in a more exact evaluation of surface contact area.

Salvage of advanced carpal collapse: proximal row carpectomy with pyrocarbon resurfacing of the capitate versus four-corner arthrodesis

In this retrospective study we report on two comparable groups of patients with advanced carpal arthritis treated with either proximal row carpectomy combined with a pyrocarbon resurfacing of the capitate (31 patients) or a four-corner arthrodesis and dorsal plating (26 patients). Follow-up time was 46 months (24–118). Except for a modestly higher radial wrist deviation in the patients treated with four-corner arthrodesis, there were no significant differences in outcomes between the groups. Asymptomatic progression of osteoarthritis in the lunate fossa was observed in four cases in both groups. Two cases were converted to a total wrist arthrodesis in the pyrocarbon group compared with one case in the four-corner arthrodesis group. Although four-corner arthrodesis remains the reference standard in the treatment of wrist osteoarthritis with involvement of the midcarpal joint, proximal row carpectomy combined with pyrocarbon resurfacing of the capitate is an alternative option. It can even be used in selected cases with erosion of the lunate fossa. Level of evidence: III

Midcarpal Structure Effect on Force Distribution through the Radiocarpal Joint

Background Wrist structure is complicated by distinct anatomical patterns. Previous studies defined radiographic wrist types based on lunate and capitate shape within the midcarpal joint. We hypothesized that these disparate structural patterns will transfer forces differently through the wrist. Objective This study aims to correlate force transferred to the distal radius and ulna with morphological measurements in cadaver arms. Methods Radiographs from 46 wrists, previously tested for force transfer between the radius and ulna, were examined. The percentage of compressive force through the distal ulna was determined by mounting load cells to the radius and ulna, while 22.2 Newton (N) tensile forces were individually applied to multiple tendons. Each wrist was tested in a neutral flexion–extension and radial-ulnar deviation position. Results Wrist type and lunate type were associated with percentage of force transfer through the ulna (p = 0.002, p = 0.0003, respectively). Percentage of force transfer was correlated with capitate circumference (p = 0.02, r = 0.34). Conclusions This study supports distinct force transfer between morphological wrist types. Clinical Relevance Understanding the mechanical significance of different structural variations in the wrist bones will improve our ability to understand wrist function and the distinctive development of wrist pathology. Level of Evidence This is a Level II study.

Anatomical Wrist Patterns on Plain Radiographs

Background: Interpreting the structure in the wrist is complicated by the existence of multiple joints as well as variability in bone shapes and anatomical patterns. Previous studies have evaluated lunate and capitate shape in an attempt to understand functional anatomical patterns. Objective: The purpose of this study was to describe anatomical shapes and wrist patterns in normal wrist radiographs. We hypothesized that there is a significant relationship in the midcarpal joint with at least one consistent pattern of wrist anatomy. Methods: Seventy plain posteroanterior (PA) and lateral wrist radiographs were evaluated. These radiographs were part of a previously established normal database, had all been read by a radiologist as normal, and had undergone further examination by 2 hand surgeons for quality. Evaluation included: lunate and capitate shape (type 1 and 2 lunate shape according to the classification system by Viegas et al.), ulnar variance, radial inclination and height, and volar tilt. Results: A significant association was found between lunate and capitate shape using a dichotomal classification system for both lunate and capitate shapes (p=0.003). Type 1 wrists were defined as lunate type1and a spherical distal capitate. Type 2 wrists had a lunate type 2 and a flat distal capitate. No statistically significant associations were detected between these wrist types and measurements of the radiocarpal joint. Conclusion: There was a significant relationship between the bone shapes within the midcarpal joint. These were not related to radiocarpal anatomical shape. Further study is necessary to better describe the two types of wrist patterns that were defined and to understand their influence on wrist biomechanics and pathology.

Wrist Arthrography

Chapter 100 describes the indications, the technique, and the imaging findings of wrist arthrography. Wrist arthrography is selectively performed in routine clinical practice for MR arthrography (MRA), typically in younger patients. The main indications include evaluation of the intrinsic interosseous wrist ligaments (scapholunate and lunotriquetral) and triangular fibrocartilage complex (TFCC) injuries. Contrast should easily inject and disperse throughout the radiocarpal joint space. Complications from contrast injection are rare and include infection and bleeding. Full-thickness tearing of any of the 3 components of the scapholunate and/or lunotriquetral ligament allows abnormal communication with the midcarpal joint. Central tearing of the triangular fibrocartilage disc allows abnormal communication with the distal radioulnar joint.