Assessment of rotation in proximal humeral osteotomy

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Acta Radiologica ISSN: 024-11 (Print) 1600-04

com/loi/iard20 Assessment of rotation in proximal

Broström To cite this article: Veli Söderlund, M.

Broström (1994) Assessment of rotation in proximal

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1 Acta Radiologica ISSN: (Print) (Online) Journal homepage: Assessment of rotation in proximal humeral osteotomy Veli Söderlund, M. Kronberg & L.-Å. Broström To cite this article: Veli Söderlund, M. Kronberg & L.-Å. Broström (1994) Assessment of rotation in proximal humeral osteotomy, Acta Radiologica, 3:3, 2-0 To link to this article: Published online: 04 Jan 20. Submit your article to this journal Article views: 4 Full Terms & Conditions of access and use can be found at

2 Arm Radiologiro 3 (1994) Fusr. 3 Printed in Denmurk. AN rights reserved Copvright 0 Actu Rudiologica 1994 ACTA R A D I 0 LOG1 CA ISSN 0-11 FROM THE DEPARTMENTS OF DIAGNOSTIC RADIOLOGY AND ORTHOPEDIC SURGERY, KAROLINSKA HOSPITAL, STOCKHOLM, SWEDEN. ASSESSMENT OF ROTATION IN PROXIMAL HUMERAL OSTEOTOMY V. SODERLUND, M. KRONBERG and L-A. BROSTROM Abstract The correlation between the shift measured on bone surface in rotatory osteotomy and the radiologic change of the retroversion angle was analyzed. The humeral head retroversion was measured radiographically in isolated humeri by means of a semiaxial projection. All bones were then osteotomized and the humeral head rotated in order to increase and decrease the retroversion. The retroversion was measured radiographically for each new rotational position of the head. The relationship between the measured shift in rotatory osteotomy and the change of retroversion was found to be linear. Twelve patients with recurrent anterior shoulder joint dislocations and a small humeral head retroversion were operated on in order to increase the retroversion. In all patients the increase of retroversion angle was smaller (%) than expected on the basis of the shift in osteotomy and humeral diameter. The mean increase of retroversion was 2'-/mm shift (range "/mm). Key words: Humerus, osteotomy; -, rotation. There are many different types of treatment available for shoulder instability. Excellent results can be expected in the traumatic type of instability from soft-tissue repair, but less frequently in generalized joint laxity and in particular not in patients with multidirectional instability. We have presented reference values for normal humeral head retroversion, and shown that many patients with anterior shoulder instability have a decreased humeral head retroversion (1, 4). In these patients soft tissue reconstruction will not stabilize the shoulder (3,, ). A rotational osteotomy of the proximal humerus to increase the retroversion of the head stabilizes the joint and gives excellent functional results with a normal range of motion (2). There are no reports on how to measure the intraoperative change of the angle. We have therefore investigated whether the angle change can be assessed by measuring the rotational shift during osteotomy. Material and Methods Humeral head retroversion was assessed in isolated humeri from skeletons using one radiograph exposed in the semiaxial projection (6). All humeri were osteotomized 6 cm below the top of the head, to achieve a level of osteotomy corresponding to an extracapsular proximal humeral osteotomy. The diameter of the humerus was measured in the osteotomy in a.p., lateral and two 4" oblique views (Table 1). A measuring tape graded in millimeters was placed on the lower edge of the osteotomy. The middle of the scale was over the medial ridge of the sulcus of the biceps tendon. Along the ridge, perpendicular to the osteotomy, a line was marked on the upper edge of the osteotomy (Fig. 1). The shaft of the humerus was firmly fixed to a stable stand. The humeral head was elastically attached to the shaft to allow rotation. The humeral head was rotated at the osteotomy in steps of 1-mm shifts to increase and decrease the retroversion of the head. The axis of the rotation was kept as central in the shaft as possible. The retroversion was assessed by radiography of each rotational position. A consecutive series of patients ( men, 2 women, mean age 3 1 years, range 20-4 years), with recurrent anterior shoulder dislocation in combination with a decreased humeral head retroversion (mean 14", range -'), were operated with an extracapsular rotational osteotomy of the proximal humerus. Four patients had surgery on the right dominant shoulder and on the left nondominant side. The humeral diameter was measured on an a.p. radiograph 6 cm below the head convexity and corrected for the magnification of 1.1. All shoulders were exposed through a deltopectoral approach. Perpendicular to the transverse osteoto- Accepted for publication October

3 2 v. S~DERLUND ET AL. plates (2). The shift between the marks was measured in millimeters after fixation (Table 2). Overhanging edges of the osteotomy were evened out to avoid wear of tendons. The shoulder joint was immobilized in internal rotation and adducted position with a sling for 4 weeks, before active exercises were allowed. Finally, the new retroversion was measured radiographically. Results There was a close to linear relationship between shift and version change (correlation coefficient 0.99) (Fig. 2). Some measurements of the bones A, B and C were excluded because the points for assessment of the retroversion angle were obscured with increasing rotation. The mean retroversion angle of the bones was 2" (range 20-41"). The mean change of version was 4.6"/mm shift. The mean diameter of the humeri in the patients in the a.p. view was mm (range mm). The mean humeral head retroversion was 14" before surgery and " after surgery. Mean shift of the osteotomy was mm (range - mm). A translation in the osteotomy was not measurable because of evened out edges in ihe osteotomy. Three months after surgery, all shoulders had a full range of motion and were stable. On follow-up radiographs there were no signs of loosening of the osteosynthetic material and all osteotomies were healed. Fig. 1. Schematic picture of measurement of the shift between marks on both sides of the osteotomy. Table 1 Isolated humeral diameters from measurements of bones. Diameter in frontal view (DAp). lateral view diameier (D1J and two 4." oblique diameters (Dobl) Bone A B C D E F G Mean SD DAP Bone diameters, mm I.2 my plane a mark was made on the lateral ridge of the sulcus of the biceps tendon. The osteotomy was performed extracapsularly 6 cm below the top of the humeral head. The humeral head was rotated in order to increase the retroversion. The osteotomy was closed with 2 semitubular Discussion Radiologic assessment of the humeral.head retroversion can be done with high precision on a semiaxial view radiograph (6). In a theoretical surgical rotation procedure, the humerus is considered circular, and the change of rotation is linear to the shift and inversely correlated to the diameter of the object. The transverse form of the proximal humerus is elliptic as the diameter varies in different projections (Table 1). The change of version was nearly liflear in all bones. The small variation can be explained by.a small error in the shift measurement and a slightly inconstant axis in the rotatory procedure of the noncircular tubular bone. There is a difference in the expected version change per millimeter shift in the bones and patients, because of larger diameters in patients (mean change 4.6"/mm and 2.0 /mm, respectively). In the patients, however, there was a change of rotation smaller than expected. The mean calculated retroversion angle (CI= x 360"/nD) was 43", but the observed mean angle was ", which is % of that expected. This could not be explained by the elliptic form of the humerus or the small errors in the rotatory procedure as shown in the isolated bones. During the operation the shift can be difficult to measure accurately within 1 mm. A 1-mm error in measurement

4 ~~~ ROTATION IN PROXIMAL HUMERAL OSTEOTOMY 29 0 Change of retroversion, degrees Shift, mrn Fig. 2. Change of rotation, "/mm shift for the isolated humeri. Each graph is displaced mm from the closest one (a). Retroversion changes of all bones with the anatomic position of the head in origo (b). Table 2 Change of retroversion angle afer rotarion osreotomy in patients. The diameter measured on radiographs in frontal view, corrected for magnijkation (1. I) Pat. Diameter, Preoperative Shift, Calculated Postop. Difference Observed Difference Change, mm retroversion, mm retroversion, observed calculated- change, pre-/post- degrees/ degrees degrees retroversion, observed %, of operative mm degrees retroversion calculated retroversion shift change I I Mean SD I I O

0 v. SODERLUND ET AL. Shift B = Shift A The shift can give a translation and a rotation in the osteotomy. The translation can cause the change of retroversion to be smaller than the calculated.

5 0 v. SODERLUND ET AL. Shift B = Shift A The shift can give a translation and a rotation in the osteotomy. The translation can cause the change of retroversion to be smaller than the calculated. The surgical technique with edge smoothening, however, makes the postoperative measurement of translation difficult. A derotation in the postoperative period is not a likely explanation. There were no signs of loosening of the osteosynthetic material on the postoperative radiographs and the shift was measured immediately after the fixation of the osteotomy. The rotatory procedure leads to a smaller change of the retroversion angle than calculated. The error most probably consists of a translation and an off-centered axis of rotation. ACKNOWLEDGMENTS This study was supported by grants from the Karolinska Institute Research Foundation and the Gustav and Ulla af Ugglas Foundation. p=a/2 Fig. 3. Centered and off-centered rotation. If the axis of rotation is displaced from A to B, the diameter is doubled and with the same shift angle p will be half of angle u. gives an average error of.% when the mean shift is mm, but is too small to explain the results in patients. If the axis of rotation is not kept in the center of the shaft axis during the procedure, but is located at the cortex opposite the site of shift measurement, the diameter is doubled. This leads to an angle change half of that with the axis at the center (Fig. 3). The observed change of retroversion is % of that calculated. This means that during operation the theoretical diameter of the rotation procedure is 1. times larger than the measured diameter. The axis of rotation is thus located between the shaft axis in the center and the opposite cortex. Request for reprinfs: Dr. Veli Soderlund, Department of Diagnostic Radiology, Karolinska Hospital, S-4 01 Stockholm, Sweden. REFERENCES 1. KRONBERG M. & BROSTROM L.-A.: Humeral head retroversion in patients with unstable humeroscapular joints. Clin. Orthop. 6 (191),. 2. KRONBERC M. & BROSTOM L.-A.: Proximal humeral osteotomy to correct the anatomy in patients with recurrent shoulder dislocation. J. Orthop. Trauma 0 (1990), KRONBERG M., BROSTROM L.-A. & POSCH E.: Stability in relation to humeral head retroversion after surgical treatment of recurrent anterior shoulder dislocation. Orthopedics 3 (1993), KRONBERG M., BROSTROM L.-A. & SODERLUND V.: Retroversion of the humeral head in the normal shoulder and its relationship to the normal range of motion. Clin. Orthop. 3 (1990), 1.. SAHA A. K.: Dynamic stability of the glenohumeral joint. Acta Orthop. Scand. 42 (191), SODERLUND V., KRONBERG M. & BROSTROM L.-A.: Radiologic assessment of humeral head retroversion. Description of a new method. Acta Radio]. (199), 01.. WEBER B. G.: Operative treatment for recurrent dislocation of the shoulder. Injury 1 (1969),.

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