POLSKI 2013, 85, 10,

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1 POLSKI PRZEGLĄD CHIRURGICZNY 2013, 85, 10, /pjs Radiological investigation of relationship between lunate type and ulnar variance Ahmed Elsaftawy Department of General Surgery, Subdepartment of Limb Replantation, Microsurgery and Hand Surgery, St Hedwig Hospital in Trzebnica Ordynator: prof. dr hab. J. Jabłecki Some variances and anatomical proportions of the wrist may contribute to development of avascular necrosis of the lunate. Kienböck s disease is more often encountered in young males, who suffer, among others, from type II of the lunate (with two joint surfaces for the capitate and hamate) and/or negative variance of ulna in relation to radius. The aim of the study was to investigate whether there exists interdependence between the simultaneous occurrence of individual types of the lunate with one of the variances of ulna in both genders. Material and methods. A retrospective analysis of 394 (n=394) radiological tests of the wrist in 174 (44%) women and 220 (56%) males aged years (average age 39 years). From the entire pool, 265 X-rays were educed in 104 females and 161 males, and no fractures or wrist instability features were could be observed. The X-rays were obtained from computer lab and archive data base at St Hedwig Hospital in Trzebnica from the beginning of January 2011 to the end of December Results. 196 cases (74%) were found with type I of the lunate and 69 cases (26%) with type II. Ulnar variance amounted to from +4.7 mm to 4.2 mm (mean value +0.9 mm). Positive ulnar variance was stated in 44 patients (16.6%), negative in 63 (23.7%) and neutral accounted for the biggest group of other 158 (59.7%) patients. Conclusions. Neutral variance of ulna is the one that occurs most often in the Polish population. There is no correlation between gender and ulnar variance. There is also lack of direct connection between occurrence of individual lunate types and ulnar variance. Key words: ulnar variance, lunate types, Kienböck s disease, avascular necrosis Anatomical variances such as negative variance of ulna so-called ulna minus, excessive falling out of the lunate from radial surface or the presence of type II of the lunate may contribute to vascularity disorder and development of avascular necrosis of the lunate (fig. 1, 2). The concept of lunate at risk refers to lunate with singular vascularity (dorsal or palmar) without an advanced network of intraosseal vessels and with negative ulnar variance. Variance of ulna is the proportion of joint surface of the radius to ulna. Positive ulnar variance in turn may occur along with the following conditions: 1) scapholunate instability, 2) ulnar impeachment syndrome, 3) triangular fibrocartilage complex injury (TFCC), 4) lunate-triquetral ligament injury. In addition, the presence of type II of the lunate with two joint surfaces both for the capitate and hamate may be connected to worse vascularity of the bone due to, among others, bigger joint surface, which is not permeated by the vessels. Injuries like fracture of distal radius, epiphyses of distal bones of the forearm, radial head may also contribute to pathological setting of ulna in relation to radius, this is why this study has excluded patients with injuries of this kind. Position of the patient s limb is also an important element when defining the ulnar variance. Position with excessive rotation of the wrist may show a false result of positive ulnar variance, and excessive supination of the wrist a false negative variance of

2 Radiological investigation of relationship between lunate type and ulnar variance 577 Fig. 1. Kienböck s disease in IIIa degree along with ulna minus variance (own materials) ulna. Correct position for defining ulnar variance should take into account 90º shoulder abduction, 90º flexion in ulnar joint with neutral position of the wrist with palmar side directed towards the X-ray cassette (1, 2, 3). Material and methods Analysis of 394 (n=394) radiological tests of the wrist in 174 (44%) females and 220 (56%) males aged years (average age 39 years). From the entire pool of radiological examinations there were distinguished 265 X-rays in 104 females and 161 males, which didn t show any fractures or wrist instability features in order to eliminate a possibility of mistake in estimation of ulnar variance. These examinations were carried out based on archive sources and computer data base at St Hedwig Hospital in Trzebnica. The tests were conducted at hospital lab from the beginning of January 2011 to the end of December These were patients admitted both in emergency mode as well as at hospital outpatient hand surgery clinic. The examinations were carried out both with 90º shoulder abduction and at 90º flexion of the ulnar joint with forearm in neutral rotation. Estimation of ulnar variance (proportion of joint surface of the radius to ulna) was done based on linear technique- distance between the line running from ulnar edge of joint surface of the radius in the direction of ulnar bone, and joint surface of ulna (fig. 3). However this technique shows a small proportion of mistake that amounts to Fig. 2. Kienböck s disease in IIIb degree along with ulna minus variance and with lowering the height of the wrist and visible rotary subluxation of the scaphoid (own materials) approximately 0.6 mm (4), that is why in order to minimalize the possibility of mistake in the results, as neural variance are considered the results within the limits from 1 to +1 mm. Evaluation of the lunate was done based on visible joint surfaces for the capitate and hamate (fig. 4, 5). Statistical tests were carried out in order to examine possible dependencies between gender, lunate type and ulnar variance. Results Radiological tests of the wrist were performed in 104 females (~40%) and 161 males (~60%). Type I observed in 196 cases (74%) (one joint surface for the capitate) and 69 Fig. 3. Ulnar variance proportion of joint surface of the radius to ulna

3 578 A. Elsaftawy Fig. 4. Different variances of ulna with type I of the lunate, A ulna neutral, B ulna plus, C ulna minus (own materials) Fig. 5. Different variances of ulna with type II of the lunate, A ulna neutral, B ulna plus, C ulna minus (own materials) cases (26%) with type II of the lunate (with two joint surfaces for the capitate and hamate). Ulnar variance amounted from +4.7 mm to 4.2 mm (mean value +0.9 mm). Positive ulnar variance was identified in 44 patients (16.6%), negative in 63 (23.7%), and neutral variance was observed in the biggest group of 158 (59.7%) patients. The table below includes results of examining dependencies between lunate type and ulnar variance. For the table above a Chi-squared test was conducted, its p-value of does not allow for rejecting the null hypothesis on independence between gender and ulnar variance. Therefore there is lack of statistically significant dependence between gender and ulnar variance. In the table below there are listed results of investigating dependencies between lunate type and ulnar variance. For the table above the Chi-squared test was also performed. p-value of 0.35 does not allow for rejecting the null hypothesis saying that there is no dependence between lunate type and ulnar variance. The dependency is thus random. Figure 6 shows the occurrence of lunate type II in single ulnar variances. Discussion Searching for a relationship between the co-existence of negative lunate variance and type II of the lunate is not coincidental. Radiological changes occurring in Kienböck s disease (avascular necrosis of the lunate) are more frequent among others with these anatomical variations of the wrist (5-8). A more frequent co-existence of negative lunate variance with the type II of the lunate increases the risk of incidence of the illness, which most often affects young males at productive age. Only early diagnosis and treatment (in early stages of the disease- up to IIIA ) may guarantee very

4 Radiological investigation of relationship between lunate type and ulnar variance 579 Fig. 6. Occurrence (in %) of lunate type II with individual ulnar bone variants good long-term results (9, 10, 11). Changes in Kienböck s disease may be visible on a regular X-ray as early as from II degree of disease advancement based on Lichtman (1, 2, 7, 11). Non-typical pains of dorsal, central part of the wrist may occur much earlier. Knowledge of anatomical variances of the wrist, typical of Kienböck s disease may turn out to be very helpful in detecting the disease in its early stages, when the image of avascular necrosis may be visible only when performing MRI test (12, 13). As far as examining the ulnar variance alone, either in publications that study anatomical variances of the wrist or in works Table 1. Numbers of patients with respect to gender (F,M) and Ulna ulnar variance Gender Ulna plus Ulna minus Ulna neutral U + U - U0 K / F M Table 2. Numbers of patients with a specified lunate type (I, II) and Ulna ulnar variance Lunate type Ulna plus U + Ulna minus U - Ulna neutral U0 I II concentrating on characteristics of Kienböck s disease, the literature is more than abundant. Ulnar variance average in these publications, among different populations ranged from 0.84 mm to mm (14-21). Most authors exploring ulnar variance in Kienböck s disease paid most attention to negative variance, where values were contained within the range from 3.1 mm to 1.22 mm. That is why results not exceeding the range 1 to +1 mm became considered as neutral variance in order to reduce the risk of mistake (22-26). Literature is however very poor as far as works exploring the co-existence of both negative ulnar variance with type II of the lunate (27) are concerned; in the above-mentioned publications, this work included, statistically there is no difference in the simultaneous occurrence of type II of the lunate and negative lunate variance. In order to exclude false results of ulnar variance, a correct position of the patient during radiological examination of the wrist ought to allow for the 90º flexure of ulnar joint with forearm positioned in neutral rotation. Despite the lack of statistically significant difference in occurrence of any of the lunate type with individual ulnar variances, in half of the cases negative lunate variance co-occurred along with second type of the lunate. These are patients who need to be given special attention because theoretically they may be more prone to contracting the disease (3, 7, 9). Conclusions 1. Neutral variance of ulna is the most frequently occurring one. 2. There is no correlation between gender and ulnar variance. 3. There is also no direct connection between occurrence of individual types of the lunate and ulnar variance. 4. Type I of the lunate is the most frequent. references 1. Thienpont E, Mulier T, Rega F et al.: Radiographic analysis of anatomical risk factors for Kienböck s disease. Acta Orthop Belg 2004; 70(5): Schuind F, Eslami S, Ledoux P: Kienböck s disease. J Bone Joint Surg Br 2008; 90(2): Dubey PP, Chauhan NK, Siddiqui MS et al.: Study of vascular supply of lunate and consider-

5 580 A. Elsaftawy ation applied to Kienböck disease. Hand Surg 2011; 16(1): Tomaino MM: Ulnar impaction syndrome in the ulnar negative and neutral wrist. Diagnosis and pathoanatomy. J Hand Surg (Br) 1998; 23: Kienbock R: Uber traumatische Malazie des Monatbeins und ihre Folgezustande: Entartungsfomen und Kompressionsfrakturen Fortschrit Rontgenstrallen 1910; 16: Jensen CH: Interosseous pressure in Kienbock s disease, J Hand Surg 1993; 18A: Lutsky K, Beredjiklian PK: Kienböck disease. J Hand Surg Am 2012; 37(9): Luch A, Garcia-Elias M: Etiology of Kienböck disease. Tech Hand Up Extrem Surg 2011; 15(1): Ledoux P, Lamblin D, Wuilbaut A et al.: A finiteelement analysis of Kienböck s disease. J Hand Surg Eur 2008; 33(3): Gelberman RH, Taleisnik J, Panagis JS et al.: The arterial anatomy of the human carpus: I. the extraosseous vascularity. J Hand Surg Am 1983; 8: Saunders BM, Lichtman D: A classificationbased treatment algorithm for Kienböck s disease: current and future considerations. Tech Hand Up Extrem Surg 2011; 15(1): Afshar A, Eivaziatashbeik K: Long-term clinical and radiological outcomes of radial shortening osteotomy and vascularized bone graft in kienböck disease. Hand Surg Am 2013; 38(2): Blanco RH, Blanco FR: Osteotomy of the radius without shortening for Kienböck s disease: a 10-year follow-up. J Hand Surg Am 2012; 37(11): Chan K., Huang P: Anatomical variations in radial lenghths in the wrists of chinese. Clin Orthop 1971; 80: Gelberman R, Salamon P, Jurist J et al.: Ulnar variance in Kienböck s disease. J Bone Joint Surg 1975; 57-A: Kristensen S, Thomassen E, Christensen F: Ulnar variance and Kienbock s disease. J Hand Surg 1986; 11-B: Czitrom A, Dobyns J, Linscheid R: Ulnar variance in carpal instability. J Hand Surg 1987; 12-A: Mandelbaum B, Bortolozzi A, Dary C et al.: Wrist pain syndrome in gymnast. Am J Sports Med 1989; 17: Nakamura R, Tanaka Y, Umaeda T et al.: The influence of age and sex on ulnar variance. J Hand Surg 1991; 16-B: Afshar A, Aminzadeh-Gohari A, Yekta Z: The association of Kienböck s disease and ulnar variance in the Iranian population. J Hand Surg Eur 2013; 38(5): Hulten O: Uber anatomische variation der handgelenkknochen. Acta Radiol 1928; 9: Sundberg S, Linscheid R: Kienböck s disease: results of treatment with ulnar lengthening. Ciln Orthop 1984; 187: Nathan P, Meadowq K: Ulnar-minus variance and Kienböck s disease. J Hand Surg 1987; 12-A: Wun-Schen C, Marotta J, Powell J: Ulnar variance and Kienböck s disease. Clin Orthop 1990; 225: Kataoka T, Moritomo H, Omokawa S et al.: Ulnar variance: its relationship to ulnar foveal morphology and forearm kinematics. J Hand Surg Am 2012; 37(4): doi: /j.jhsa Epub 2012 Mar Laino DK, Petchprapa CN, Lee SK: Ulnar variance: correlation of plain radiographs, computed tomography, and magnetic resonance imaging with anatomic dissection. J Hand Surg Am 2012; 37(1): Schuurman AH, Maas M, Dijkstra PF, Kauer JM: Ulnar variance and the shape of the lunate bone. A radiological investigation. Acta Orthop Belg 2001; 67(5): Received: r. Adress correspondence: Trzebnica, ul. Prusicka 53/55 elsaftawyahmed@gmail.com