Analyzing the reduction quality of the distal radioulnar joint after closed K-wire transfixation in a cadaver model: is supination or neutral position superior?

INTRODUCTION: Distal radioulnar joint (DRUJ) instabilities are challenging and their optimal treatment is controversial. In special cases or when reconstruction of the stabilizing triangular fibrocartilage complex (TFCC) fails, K-wire transfixation can be performed. However, no consensus has been reached regarding the rotational position of the forearm in which this should be done. Therefore, it was investigated whether anatomical reduction would best be achieved by transfixation in neutral position or supination of the forearm. MATERIALS AND METHODS: Twelve cadaveric upper limbs were examined before dissection of the DRUJ stabilizing ligaments and after closed transfixation in both positions by C-arm cone-beam CT. Whether this was first done in neutral position or in supination was randomized. The change in the radioulnar ratio (RR) in percentage points (%points) was analyzed using Student's t-test. RR was used since it is a common and sensitive method to evaluate DRUJ reduction, expressing the ulnar head's position in the sigmoid notch as a length ratio. RESULTS: The analysis showed an increased change in RR in neutral position with 5.4 ± 9.7%points compared to fixation in supination with 0.2 ± 16.1%points, yet this was not statistically significant (p = 0.404). CONCLUSIONS: Neither position leads to a superior reduction in general. However, the result was slightly closer to the anatomical position in supination. Thus, transfixation of the DRUJ should be performed in the position in which reduction could best be achieved and based on these data, that tends to be in supination. Further studies are necessary to validate these findings and to identify influential factors.

Evaluation of radiological instability signs in the distal radioulnar joint in children and adolescents with arthroscopically-verified TFCC tears.

INTRODUCTION: Recent reports in the adult literature reported the use of standardized radiographic measurement techniques to determine distal radioulnar joint (DRUJ) instability. The aim of this study was to evaluate the efficacy and accuracy of (1) the MRI-based modified radioulnar ratio technique and (2) the pisoscaphoid (PiSca) and radioulnar (RaUl) distances in true lateral radiographs in children and adolescents with arthroscopically-verified TFCC tears. MATERIALS AND METHODS: We retrospectively assessed lateral wrist radiographs and axial MRI sequences of 18 adolescent patients (22 wrists) who had arthroscopically-confirmed TFCC tears and compared them to similar imaging of a control group of 28 healthy patients (28 wrists). Three raters assessed the images twice in a 2-week interval. Intraclass correlation coefficients (ICCs), unifactorial ANOVA, and ROC analysis were performed with regards to the different radiographic variables. RESULTS: The interrater ICCs were almost perfect for all measurements except RaUl1, which showed a substantial agreement (0.751) among the three observers. The intrarater ICCs were almost perfect when measuring PiSca and MRI, and substantial to almost perfect for RaUl. Pearson's correlation showed a moderate, positive correlation between PiSca and RaUl distances (r = 0.608; p < 0.001), and a moderate, negative correlation between RaUl distance and MRI shift (r = - 0.486; p = 0.010). When the three core groups (peripheral, central tear, controls) were compared to each other regarding the radiographic instability parameters, only the MRI shift revealed a statistically significant difference (p = 0.003). Comparisons revealed significant differences between patients and controls (p = 0.004) and peripheral tears vs. controls (p = 0.001 and p = 0.010). The ROC analysis revealed a significant AUC only for the MRI (AuC 0.787 and p = 0.002). CONCLUSIONS: Children and adolescents with peripheral TFCC tears showed significantly increased instability parameters in MRI compared to controls. These measurement techniques are no replacement for a thorough clinical examination but may be helpful for indicating diagnostic wrist arthroscopy in ambiguous cases. LEVEL OF EVIDENCE: Level III; Diagnostic.

Corrective osteotomy for malunion of distal diaphyseal/metaphyseal radius or ulna fracture affecting stability of the distal radioulnar joint.

BACKGROUND: We postulated that residual distal radioulnar joint (DRUJ) instability after distal diaphyseal or metaphyseal fracture in the radius or ulna may occur due to malaligned or malunited bony structures as well as primary or secondary soft issue stabiliser. Here, we report the outcomes of corrective osteotomy in a retrospective study. METHODS: Patients undergoing the osteotomy for DRUJ instability between March 2000 and February 2018 were included in the study. Thirteen patients were evaluated. The initial injury occurred at a mean age of 12.3 years and corrective osteotomy was performed at a mean age of 20.8 years. The mean follow-up period was 33.1 months. The male to female ratio was 8:5 and the corrected radius/ulna ratio was 11:2. DRUJ instability was diagnosed clinically and radiologically based on the stress/clunk test and the distance between the cortex of the radius, and the radioulnar ratio. All osteotomies in the radius and ulna were of the open wedge type and were performed using plates/screws. RESULTS: The radioulnar ratio was significantly higher than the normal ratio (p < 0.001). All osteotomies healed well without any serious complications. The preoperative distance between the cortex of the radius and ulna was significantly decreased at the final follow-up, from 4.74 ± 0.82 to 1.16 ± 0.46 mm (p < 0.001). Positive findings of two instability tests were all converted to negative. The ranges of motion of the flexion-extension and pronation-supination arcs were significantly improved. Finally, preoperative VAS pain and DASH scores improved to 0.23 ± 0.44 and 3.92 ± 1.84, respectively (p < 0.001). CONCLUSIONS: Malunited radius or ulna plays a role in DRUJ instability, affecting the bony geometry in terms of the relationship between the sigmoid notch and ulnar head. Treatment of malunion by corrective osteotomy represents a useful option for resolving instability. LEVEL OF EVIDENCE: Level IV, Retrospective therapeutic study.