Defining postoperative stability in children with radial polydactyly.

UNLABELLED: There is little fundamental data on paediatric metacarpophalangeal joint instability in radial polydactyly following surgical reconstruction. We evaluated 27 thumbs in a healthy paediatric population (Group A: eight girls and 19 boys with a mean age of 9.7 years (range 2.7-14.2)) and 12 thumbs following Wassel-IV reconstruction (Group B: eight girls and four boys with a mean age at follow-up of 10.6 years (range 2.7-13.2)). Metacarpophalangeal joint radial deviation, ulnar deviation on stress testing, interphalangeal joint and metacarpophalangeal joint alignment on posterior-anterior radiographs were measured and scored according to parameters defining joint instability. The aim of our study was to provide fundamental data on thumb metacarpophalangeal joint mobility patterns and alignment for further postoperative evaluations in children. The average ulnar deviation and radial deviation on stress testing of the healthy (Group A) metacarpophalangeal joints was 25° (10°-45°) and 30° (10°-55°), respectively. In the operated (Group B) thumbs, the ulnar deviation and radial deviation was greater at 35° (10°-55°) and 30° (10°-70°). Ulnar deviation (UD) of the proximal phalanx at the metacarpophalangeal joint on posterior-anterior radiographs was a mean of 10° (range -10°-30°) in Group B; this was significantly greater than in Group A at a mean of 5° (range -5-20°) (p = 0.029). The mean radial alignment of the interphalangeal joint (distal phalanx relative to the proximal phalanx) was significantly higher in Group B (15°) than Group A (0°) (p = 0.221). In the literature on radial polydactyly, cut off values defining metacarpophalangeal joint instability in children range from 5° to 20°. According to our results, high but physiological metacarpophalangeal joint mobility of the thumb needs to be taken into consideration when evaluating children following reconstruction. Ulnar or radial deviation greater than 30°, in combination with the lack of a definite end point on metacarpophalangeal joint stress testing, may be regarded as unstable. Based on our study on healthy paediatric and reconstructed thumbs, comparison of joint stability with the healthy contralateral hand is recommended in order to define pathological instability. LEVEL OF EVIDENCE: II.

Supporting the collateral ligament complex in radial polydactyly type Wassel IV.

Despite anatomical metacarpophalangeal joint (MCPJ) reconstruction in radial polydactyly (RP) Wassel IV, the prevention of long-term deformity and instability is still an issue. We report on clinical results following our modified surgical procedure with additional support of the hypoplastic radial collateral ligament complex (RCLC) after musculoligamentous MCPJ reconstruction. Fourteen patients (male: 10, female: 4) with radial resection of isolated RP Wassel IV (1987-2006), average age at surgery 1.7 years (0.6-8.6) were included. Distribution to group A and B depended on the procedure for MCPJ reconstruction. In group A (N = 7), RCLC reinsertion + reinforcement using autologous tendon grafts was performed (follow-up: 4.6 years (1.4-6.9)). Group B (RCLC reinsertion without support) consisted of N = 7 patients; follow-up: 9.6 years (8.2-20.2). The healthy contralateral hand (control A/control B) served as a control. Results were evaluated using our modified Tada-score considering: range of motion (ROM), interphalangeal joint (IPJ) and MCPJ stability on stress examination, palmar abduction and grip strength. Better score results (maximum 10) were seen in A: 7.3 (6-9) compared to B: 6.6 (4-10). Subscore 'stability' A: 1.1 (0-2); B: 0.9 (0-2) and 'alignment' A: 0.86 (0-2); B: 0.57 (0-2) showed greatest influence on the score result. Ulnar angulation at MCPJ level compared to healthy thumbs (control A + B) was greater (p < 0.05), with 11.4° (10-20) in group A and 14.3° (-5 to 30) in group B compared to 0° in control A and 5.7° (0-17) in control B. MCPJ ulnar deviation in A + B: 25° (0-35) compared to healthy thumbs control A + B was higher (p < 0.05). Ulnar deviation was higher in B 45° (30-60) compared to 34° (20-50) in A. In B, instability was evident in four, in A, only in one patient. In B, one patient required two re-operations due to MCPJ instability. Equivalent results were recorded regarding pinch grip and palmar abduction. Anatomical MCPJ reconstruction in combination with autologous support of the hypoplastic RCLC to enhance long-term stability is recommended.

Optical and electromagnetic tracking for navigated surgery of the sinuses and frontal skull base.

BACKGROUND: New hardware and software algorithms in electromagnetic tracking for computer assisted surgery (CAS) have been developed. We aimed to compare electromagnetic tracking for navigated procedures in frontal skull base surgery to optical tracking. METHODS: Target registration error (TRE) was determined in 6 anatomic specimens in an experimental wet-lab. As targets, 6 titanium screws were evenly distributed over the surgical areas of interest from the frontal sinus to the clivus. Optical tracking and electromagnetic tracking was evaluated in identical software environment using a last generation commercially available navigation system. RESULTS: Submillimetric application accuracy could be achieved with both tracking modalities. Optical was more accurate than electromagnetic tracking and its reliability was better. Target position did not influence TRE, however TRE varied significantly from skull to skull. CONCLUSIONS: Although less accurate than optical tracking, electromagnetic tracking still offers excellent accuracy and reliability for anterior skull base surgery. Electromagnetic tracking is not dependent on direct line of sight between its hardware components and therefore easily integrated even in cluttered operating theatres.