UvA-DARE (Digital Academic Repository) Characterizing scaphoid nonunion deformity using 2-D and 3-D imaging techniques ten Berg, P.W.L. Link to publication Citation for published version (APA): ten Berg, P. W. L. (2017). Characterizing scaphoid nonunion deformity using 2-D and 3-D imaging techniques General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (http://dare.uva.nl) Download date: 23 Apr 2018
CHAPTER 6 Carpal Intraosseous Cyst Formation Following Scaphoid Nonunion P.W.L. ten Berg M. Foumani S.D. Strackee J Hand Surg Eur Vol. 2016 Sep; 41(7):769-71 (Short report letter)
ABSTRACT Development of carpal intraosseous cystic lesions may indicate advanced degenerative changes in the scaphoid nonunion wrist. Using CT and MRI scans from 76 scaphoid nonunion, we retrospectively analyzed the incidence and location of these cysts throughout the carpal wrist and compared this with cyst formations in intact wrists on the contralateral CT images, serving as control group. We also analyzed the relation of cyst formation with time from scaphoid injury to scan. Scaphoid nonunions of longer duration were associated with cyst formation in multiple carpal bones, except for the trapezial and pisiform bone. Compared to the control group, we observed an unusual high incidence of trapezoid cysts in injured wrists. We believed that these trapezoid cysts are induced by local mechanical stress of the medial aspect of the distal scaphoid fragment, and may serve as additional radiologic parameter indicating cartilage defect and erosion. 64 Chapter 6
INTRODUCTION Scaphoid cysts are often observed around sites of fracture nonunion, indicating a declining healing potential. 127 We often see cysts in carpal bones surrounding scaphoid nonunions. These cysts are classified as subchondral degenerative cysts if they are secondary to joint degeneration. 128 Their presence is not typically taken into account when staging scaphoid nonunion advanced collapse (SNAC) wrist. 58 The aim of this study was to report the sites and incidence of intra-osseous cysts shown on CT or MRI scans following scaphoid nonunion. MATERIALS AND METHODS We reviewed the CT or MRI scans of 73 patients with 74 scaphoid nonunions. There were seven women and 66 men with a mean age of 32 (range: 14 66) years. There were six unilateral and 58 bilateral pre-operative CT scans and 17 unilateral preoperative MRI scans. The opposite uninjured wrists in the bilateral scans served as controls. Cysts were measured with an onscreen measurement tool by two observers. Only relative large cysts (> 3 mm), 128 which were clearly distinguishable, were included for analysis. This study was approved by our Ethical Committee. RESULTS 6 In 21 (28%) patients, bone cysts were only visible in the scaphoid. In 15 (20%) patients there was cystic development in other bones in the wrist (Table 6.1). There were nine (12%) trapezoid, six (8%) capitate, four (5%) hamate, two (3%) lunate and two (3%) triquetral cysts. There were no trapezium or pisiform cysts. Based on the Mann-Whitney U test, older nonunions were associated with cystic development more widely in the wrist (p =.008). All cysts outside the scaphoid showed cortical penetration to the joint space. Most trapezoid cysts were eccentrically on the ulnar side (Figurre 6.1). In the capitate bone, besides cysts facing the trapezoid/distal scaphoid fragment, there were also cysts facing the hamate bone ulnarly and lunate proximally. In the healthy wrists we saw eight cysts (14%): four in the capitate; two in the lunate; one in the scaphoid bone; and one in the trapezium (Table 6.1). Carpal Intraosseous Cyst Formation Following Scaphoid Nonunion 65
Table 6.1 Incidence of bone cysts in wrists with a scaphoid nonunion, and in healthy wrists. Total No cysts Cysts in Scaphoid only Other Carpal Cysts Injured wrists (number) 74 (100%) 38 (51%) 21 (28%) 15 (20%) Time from scaphoid injury 25 (4 508) 16 (4 373)* 21 (5 508) 189 (4 362)* (months; median(range)) Healthy wrists (number) 58 (100%) 50 (86%) 1 (2%) 7 (12%) *Significant difference in time between groups: p =.008 DISCUSSION The exact pathogenesis of subchondral degenerative cysts in osteoarthritic joints is unclear. 128 One theory suggests that elevated intra-articular pressure may cause intraosseous herniation of synovium. The other suggests that mechanical stress results in micro-fractures and vascular insufficiency causing cystic necrosis. 129 It is difficult to differentiate between degenerative cysts and pre-existing intraosseous ganglia. Our finding that scaphoid nonunions of longer duration were associated with cysts in multiple carpal bones, except for the trapezium and pisiform, suggests that at least some of the cysts have formed after scaphoid injury. Furthermore the incidence of carpal cysts varies considerably when comparing healthy wrists to injured wrists. Schrank et al 128 evaluated intraosseous ganglia in 208 cadaveric wrists without scaphoid injury using radiographs and MRI scans. They found an overall incidence of 9.6%, with trapezoid ganglia in only 0.7%. Most ganglia were located in the lunate and capitate, which is consistent with the data in our control group. Waizenegger 130 reviewed 14 case series; none of the 147 ganglions were located in the trapezoid. In the injured wrists in this study trapezoid cysts occurred in 12%. Although causality cannot be proven, we believe that trapezoid cysts are induced by local mechanical stress of the distal scaphoid fragment, and therefore may serve as additional radiologic parameter indicating degenerative changes. 66 Chapter 6
6 Figure 6.1 (A) and (B) Coronal CT slides of scaphoid nonunions of, respectively, 25 years and 21 years duration, showing trapezoid cysts, facing the capitate bone ulnarly. (C) and (D) Coronal MRI images of scaphoid nonunions of, respectively, five months and 15 years duration, showing trapezoid cysts, facing the capitate bone ulnarly as well. Carpal Intraosseous Cyst Formation Following Scaphoid Nonunion 67