Carpal bossing - review and an unrecognized variation. Poster No.: P-0053 Congress: ESSR 2014 Type: Authors: Keywords: DOI: Educational Poster K. B. Puhakka, L. Roemer, B. Munk; Aarhus C/DK Developmental disease, Diagnostic procedure, CT, Musculoskeletal system, Extremities 10.1594/essr2014/P-0053 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.essr.org Page 1 of 8
Learning objectives To draw attention to carpal bossing as cause of pain and functional disability, and to present and discuss a not previously described anatomic variation of the condition. Background Carpal bossing is a bony prominence on the dorsal aspect of the second and/or third metacarpal joint. The etiology has been suggested to be traumatic, degenerative, congenital, or caused by an accessory ossicle. Rarely the cause can be a coalition between the second metacarpal bone and the trapezoid, but other variations are known: coalition of the third metacarpal-capitate joint, the capitate-trapezoid joint, and the second/third metacarpal joint. Carpal bossing can lead to i.e. pain, limited motion, tenosynovitis, and osteoarthritis. Other rare complications have been described, i.e. rupture of the extensor tendon. Carpal bossing can be mistaken for a ganglion, and precise diagnosis is necessary for treatment. This can be either conservative (NSAIDs and/or immobilization), or surgical excision of the mass. The latter though with the risk of instability of the involved joints leading to persistent or worsened symptoms. Imaging findings OR Procedure Details Using conventional X-ray examination specific carpal boss views can be made, but in spite of this, it can be difficult to profile the joints properly. CT-scanning provides an excellent characterization of the condition, both by depicting exact anatomical details and by evaluating degenerative changes. Figure 1 shows CT of a normal joint between the third metacarpal bone and the trapezoid in a 35 year old man. In figure 2 we present an example of membranous coalition between the third metacarpal bone and the trapezoid. Figure 3 is a sagittal view of the changes bridging the joint space with only a narrow space left. The patient was a 36 year old man with four months of complaints and signs of carpal bossing. Page 2 of 8
Anatomical studies describe the presence of small ligaments between the third metacarpal and the trapezoid, but coalition in this position has to our knowledge not yet been described in the literature. One reason of carpal bossing can be a persistent congenital ossicle, the os styloideum (figure 4, 61 year old man). A possible cause of the unusual coalition described in figure 2 and 3 could be a variation, in which the os styloideum has been partially fused. Images for this section: Fig. 1: Normal joint between the third metacarpal and the trapezoid. Page 3 of 8
Fig. 2: Membranous coalition between the third metacarpal and the trapezoid. Page 4 of 8
Fig. 3: Sagittal view of the membranous coalition shown in fig. 2. Page 5 of 8
Fig. 4: Os styloideum. Page 6 of 8
Conclusion Carpal bossing should be considered a possible differential diagnosis in patients with pain and a protruding mass at the dorsal aspect of the wrist. CT-scanning is recommended to describe the condition in details, especially before planning surgery. Rare anatomical variants can occur. References Alemohammad AM, Nakamura K, El-Sheneway M, Viegas SF. Incidence of Carpal Boss and Osseous Coalition: An Anatomic Study. J Hand Surg 2009; 34A: 1-6. Clarke AM, Wheen DJ, Visvanathan S, Herbert TJ, Conolly WB. The Symptomatic Carpal Boss. Is Simple Excision Enough? J Hand Surg 1999; 24B: 591-595. ConwayWF, Destouet JM, Gilula LA, Bellinghausen HW, Weeks PM. The Carpal Boss: An Overview of Radiographic Evaluation. Radiology 1985; 156: 29-31. Hazlett JW. The third Metacarpal Boss. International Orthopaedics. 1992; 16: 369-371. Loréa P, Scgmitz S, Aschilian M, Chirla-Dobrea A, Petrea AD. The Preliminary Results of Symptomatic Carpal Boss by Wedge Joint Resection, Radial Bone Grafting and Arthrodesis with a Shape Memory Staple. J Hand Surg Eur 2008; 33E: 2: 174-178. Nakamura K, Patterson RM, Viegas SF. The Ligament and Skeletal Anatomy of the Second to Fifth Carpometacarpal Joints and Adjacent Structures. J Hand Surg 2001; 26A: 1016-1029. Park MJ, Namdari S, Weiss AP. The Carpal Boss: Review of Diagnosis and Treatment. J Hand Surg 2008; 33A: 446-449. Williams MR, Fullilove SM. Re: A carpal Boss leading to Extensor Tendon Ruptures - A case Report. J Hand Surg 2008; 33: 223. Page 7 of 8
Personal Information Page 8 of 8