Open Ulnar Shortening for Ulnocarpal Impaction

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RATIONALE AND BASIC SCIENCE PERTINENT TO THE PROCEDURE

Milch is credited with the first surgical description in 1939 of an ulnar diaphyseal shortening to treat an ulnar-plus deformity secondary to a radial fracture and subsequent epiphyseal arrest in a 16-year-old. Milch used a free-hand cutting technique and a rudimentary circlage wire fixation of the ulna. Dwyer introduced the concept of ulnar shortening with two-screw fixation of the osteotomized ulna to treat Madelung’s deformity in 1955. Darrow and Linscheid and associates popularized the addition of plate and screw fixation of the transverse free-hand osteotomy of the ulnar diaphysis. A dedicated system (Creative Medical Designs, Inc, Tampa, Florida) was subsequently introduced in 1993, permitting the performance of a precisely parallel 45-degree oblique osteotomy with a specialized saw blade, dynamic compression of the osteotomy, introduction of an interfragmentary screw at a precise 22-degree angle, and fixation with a dedicated ulnar plate. Using the dedicated system described in this chapter, precision ulnar shortening ranging from 3.5 to 18.1 mm became possible. Labosky and Waggy elegantly demonstrated the variation in the amount of ulnar shortening obtained as a consequence of altering the angle of the osteotomy. In addition, they highlighted the inconsistent amount of shortening that occurred as a result of the variable blade thickness and teeth offset (kerf) dependent on the saw blade manufacturer and even within a given manufacturer’s product line.

INDICATIONS FOR ULNAR SHORTENING

The initial indication for ulnar shortening is an ulnar impaction syndrome resulting from a positive ulnar variance and frequently following a distal radial fracture associated with subsequent metaphyseal subsidence. X-ray demonstration of cystic involvement of the lunate due to chronic impaction often accompanies this positive ulnar variance ( Fig. 17-1 ). Over time, many other indications have evolved, which are also amenable to treatment by ulnar shortening.

Triangular Fibrocartilage Tear

Triangular fibrocartilage lesions treated by arthroscopic debridement often are treated concurrently or as a secondary procedure with ulnar shortening in the presence of an ulnar positive or dynamic ulnar-plus variance.

Lunotriquetral Ligament Tear

Patients with lunotriquetral ligament tears may also be candidates for ulnar shortening in lieu of lunotriquetral fusion or capsulorrhaphy. Magnetic resonance arthrograms may clearly demonstrate occult ligament tears that are not necessarily associated with lunotriquetral joint instability and that would necessitate a more aggressive procedure such as a lunotriquetral arthrodesis.

Essex-Lopresti Injury

Patients who have sustained Essex-Lopresti injuries with radial head resection or arthroplasty with subsidence are also considered candidates for ulnar shortening. However, further proximal radial migration could contribute to a resultant secondary ulnar-plus variance, and patients should be adequately counseled.

Madelung’s Deformity

Patients with mild-to-moderate Madelung’s deformity ( Fig. 17-2 ) associated with an ulnar-plus deformity are also frequently considered appropriate candidates for ulnar shortening.

Radial Malunion Osteotomy with Persistent Ulnar-Plus Variance Intraoperatively

Radial malunion patients undergoing a radial metaphyseal osteotomy and grafting may maintain an ulnar variance intraoperatively due to the effect of soft tissue constraints and thus may be considered for a concurrent ulnar-shortening osteotomy.

Minimal Radial Ulnar Degenerative Arthritis

Minimal osteoarthritis of the distal radioulnar joint may also constitute an indication for ulnar-shortening osteotomy. The concept proposed by Scheker and Severo is to reduce pain by changing the contact area of the radioulnar articular surfaces as a result of the ulnar-shortening osteotomy.

Radial Malunion in the Elderly with Positive Ulnar Variance

Elderly patients with settled radial malunions and moderate radial articular dorsiflexion with resultant positive ulnar variance may be candidates for ulnar shortening despite a less than perfect radial reduction. An ulnar shortening is clearly less invasive compared with a radial malunion osteotomy and grafting and may provide the patient with significant ulnar-side pain reduction and increased functionality.

CONDITIONS FOR OSTEOTOMY

Age Range

Young women age 14 to 16 years and young men age 16 to 18 years with closed epiphyses constitute the starting age range for ulnar shortening for most surgeons. All older age groups including the active elderly patient 85 to 90 years old could be considered appropriate candidates for this procedure.

Timing

Once a clear-cut ulnar-plus variance ensues, there is little reason to delay shortening of the ulna. In some instances, as in the presence of a triangular fibrocartilage tear, ulnar shortening may be delayed, pending the results of a triangular fibrocartilage tear debridement. For some other surgeons, concurrent treatment is advocated particularly when a positive ulnar variance exists.

CONTRAINDICATIONS

Absolute

Significant osteoarthritis of the distal radioulnar joint is an important contraindication to undergoing ulnar shortening.

Relative

Cigarette smokers have a higher risk of delayed union and nonunion, and these patients should be adequately counseled about this possibility before surgery. Teenagers with open radial and ulnar epiphyses may be questionable candidates for ulnar shortening unless their potential for additional growth may be anticipated and calculated into the amount of shortening that is planned.

SURGICAL TECHNIQUE

Instrumentation

The Generation II surface mount saw guide or Generation I wrap-around saw guide permits the performance of precise 45-degree oblique osteotomies resulting in ulnar shortenings of 3.5 to 18.1 mm ( Fig. 17-3 ). The advantage of a precision saw guide that is surface-mounted (Generation II) is that the surgeon has the option of placing the guide on either the volar-ulnar or ulnar-subcutaneous surface. Although some surgeons have advocated dorsal placement, this author has no personal experience with this application.

The streamlined Generation II compression device that snugly straddles the plate provides for significant compression capabilities without fear of rotatory abnormalities ( Fig. 17-4 ). With digital manual pressure, the surgeon has the option of angulating the distal portion of the ulna dorsally or volarly during the compression procedure when the subcutaneous plate location is chosen. If the volar position is chosen, only radial-ulnar deviation of the distal fragment is possible owing to the orientation of the oblique osteotomy.

The angled drill guide and drill sleeve facilitate application of the interfragmentary screw at 22 degrees to the osteotomy. This guide fits into the circular recess of the fixed block of the compression device, and thus free-hand drilling of the interfragmentary hole is avoided in most instances. Plate benders with both pass-through and open slots permit plate contouring to configure the plate to the contour of the ulna. In the subcutaneous position, this contouring is usually convex away from the ulna, such that there is approximately 2 mm off of a flat surface in the midportion of the plate if the plate were placed on a flat surface. For volar plate placement, the ulna is often linear except for the distal portion, which angles dorsally for the distal portion of the plate ( Fig. 17-5 ). In this case, the plate needs to be contoured appropriately.

Patient Position

Patients are positioned supine with the elbow resting on the table and fingers held vertically toward the ceiling. Right-handed surgeons sit between the extremity and the patient’s body for a left ulnar shortening and between the extremity and the patient’s head for a right ulnar shortening. Left-handed surgeons find it easiest to sit between the patient’s head and the extremity for a left ulnar shortening and between the extremity and the patient’s body for a right ulnar shortening. This position also enables clear visualization of the blade in the proximal-to-distal orientation of the sagittal saw during the osteotomy.

Tourniquet

A tourniquet is advocated to permit excellent visualization during the procedure. This should be well padded and placed high in the axilla. The tourniquet pressure is set at approximately 100 mm Hg above the systolic pressure.

Incision Placement and Dissection

A 10-cm incision is made along the ulnar subcutaneous border between the extensor carpi ulnaris and the flexor carpi ulnaris. Soft tissues are retracted and a periosteal incision is made to reflect the periosteum from the ulna. Some surgeons may elect to keep the periosteum intact and place the plate directly on the periosteal surface. Soft tissues must be protected at all times, particularly at the site of the intended osteotomy. To ensure protection of soft tissues, a malleable Davis brain retractor may be placed around the ulna at the site of the intended osteotomy ( Fig. 17-6 ). This should assure the surgeon that all structures including the ulnar nerve and artery and the flexor and extensor tendons are protected at all times.

Saw Guide Placement

The distal end of the plate should be approximately 3 cm proximal to the distal ulnar articular surface. The ulnar subcutaneous surface is slightly convex, but plate placement is easily accomplished despite the absence of a completely flat surface. Surgeons desiring a more protected location may choose to place the plate anteriorly on the ulnar surface. Slightly more soft tissue retraction is required during the osteotomy process if this volar location is chosen. The ulnar plate may be first placed on the ulna and marked to ensure appropriate location for the saw guide placement ( Fig. 17-7 ). Hole number 2 of the surface mount saw hole is aligned over this mark ( Fig. 17-8 ). Once the straight drill guide is applied on the saw guide surface, hole number 2 is drilled with a 2.5-mm drill bit ( Fig. 17-9 ). A 3.5-mm cortical screw of appropriate length is applied after measuring and tapping the screw hole ( Fig. 17-10 ). Self-tapping screws are generally avoided because of concern over the screw cutting a new bone thread as a result of subsequent screw removal and reinsertion. The straight drill guide is reinserted to permit drilling of hole number 4 ( Fig. 17-11 ). A 3.5-mm cortical screw is inserted after the hole is measured and tapped ( Fig. 17-12 ). Final fixation of the saw guide is accomplished with application of screw number 3 ( Fig. 17-13 ).