Ulnar Head Implants: Unconstrained

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CHAPTER 36 Ulnar Head Implants: Unconstrained

The ulnar head is the keystone for mobility and stability of the ulnar-sided wrist as well as the forearm. It not only is one of the joint partners creating the distal radioulnar joint (DRUJ) but also represents an integral part of the wrist joint. Biomechanically, it represents the only fixed, nonmoving anatomical structure at the wrist level. It, therefore, supplies the bony support around which the radius with the wrist and hand rotates in the DRUJ. Arthrotic destruction of the DRUJ will lead to painful limitation of forearm rotation and reduction of grip strength and therefore compromise hand function. Arthrotic derangement may be the result of intra-articular fractures of the DRUJ either with direct damage of the cartilage of the ulnar head or the sigmoid notch in comminuted fractures or secondary destruction due to intra-articular malunion of the joint line. However, the most common origin consists of the malunited extra-articular distal radius fracture. The dorsal or palmar angulation of the distal radial fragment with loss of the physiological ulnar inclination and shortening of the radius will lead to incongruity of the DRUJ and over time result in arthrotic derangement of this joint. I, therefore, consider the malunited extra-articular distal radius fracture a prearthrotic deformity of the DRUJ.¹

Several salvage procedures have been described to reduce the pain and restore forearm rotation in patients with symptomatic DRUJ destruction, including ulnar head resection ²^–⁴ and the hemi-resection interposition technique.⁵ Partial loss of the ulnar head sacrifices the attachment of the palmar ulnocarpal ligaments and the force transfer from the radius onto the ulnar head. Loss of the ligament attachment will result in a palmar drop of the ulnar-sided wrist with a supination deformity of the hand and a dorsally prominent distal end of the ulna. In a way this is comparable to the well-described caput ulnae deformity in rheumatoid patients. The deformity does not truly represent an “instability of the distal end of the ulna” but an instability of the ulnar-sided wrist. Loss of the bony support of the radius in the DRUJ leads to radioulnar narrowing or impingement during forearm rotation and wrist loading and can radiologically be demonstrated on the transverse loading stress views described by Lees and Scheker (Fig. 36-1).⁶

FIGURE 36-1 A, Posteroanterior radiograph after hemi-resection interposition arthroplasty of the DRUJ. B, Transverse loading view demonstrating radioulnar impingement.

A completely different concept to treat the painfully destroyed DRUJ consisting of fusion of the DRUJ and segment resection proximal to the ulnar head to restore forearm rotation was described by Sauvé and Kapandji in 1936.⁷ With this procedure the supination deformity and the instability at the DRUJ level is prevented as the attachments of the ulnopalmar ligaments and the triangular fibrocartilage complex (TFCC) remain. However, in pronation underloading of the hand the dynamic dorsal stabilizers of the radius and the wrist may not be sufficient to prevent palmar drop of the wrist and hand in relation to the distal end of the ulna, therefore leading again to a dorsally prominent distal ulnar stump. Furthermore, on transverse loading of the hand there is no anatomical structure to prevent the radius to fall onto the distal end of the ulna, resulting in radioulnar impingement (Fig. 36-2).^8,⁹

FIGURE 36-2 Radioulnar impingement after a Sauvé-Kapandji procedure.

The concept to prevent development of this instability using an ulnar head spacer in rheumatoid patients was first described by Swanson.¹⁰ This is no longer recommended because of the high failure rate of the Silastic spacer material and secondary Silastic-induced synovitis.¹¹^–¹⁵

To overcome the secondary “painful instability of the distal ulna,” several stabilizing soft tissue procedures using part of the flexor and/or the extensor carpi ulnaris tendon have been described. None of these procedures was found to reliably restore the stability or reduce symptoms in biomechanical ¹⁶ or clinical^17,¹⁸ studies. Wide resection of the ulna¹⁹ as well as lengthening procedures after excessive shortening of the ulna²⁰ have been advocated but did not resolve the symptoms in my own or other surgeons’ experience.¹⁷ Considering the biomechanical and clinical shortcomings of the above-described resection procedures, Herbert developed the concept of restoring stability to the DRUJ as well as the wrist joint and the continuity of the ulna by means of an ulnar head prosthesis.

Based on the results of anatomical, radiological, and biomechanical studies of the distal ulna, the ulnar head, and the DRUJ between 1992 and 1994, Timothy Herbert doveloped together with me a two-component modular system for ulnar head replacement in cooperation with Martin-Medizin-Technik (Tuttlingen, Germany). It consists of three sizes of replacement heads and three stem sizes. To restore an adequate length of the ulna after a previous resection arthroplasty, each stem size of the prosthesis is provided with three collar lengths. To avoid the problems associated with cement, particularly in small bones, we decided to use a noncemented stem, allowing osseous integration. Porous-coated titanium was chosen because of its biocompatibility and a modulus of elasticity very similar to that of bone. The head of the prosthesis is composed of ceramic (zirconium oxide) because it was believed to be the most suitable material for articulation with joint cartilage due to its biocompatibility.

Following the development of the prosthesis a three-phase clinical study design was developed. Initially, three patients with painful instability of the wrist and forearm after resection arthroplasty were treated in 1995 with promising early results.²¹ The second phase consisted of a prospective multicenter study limited to another 20 patients. Because of the excellent mid-term results of these patients,²² the prosthesis was released to other surgeons. The third phase consisted of the evaluation of the long-term results, and all patients with a follow-up of more than 5 years are currently under review.

Indications

Before further outlining the indications for the ulnar head prosthesis, it is important to emphasize that no implant will ever function as well as the original ulnar head. Therefore, ulnar head excision is only justified if the joint surface of the DRUJ is irreversibly destroyed. In any other pathological process of the DRUJ every attempt must be made to restore the DRUJ and therefore prevent the possible development of arthrotic joint destruction.

Originally the procedure was developed to solve the unsolvable and to overcome the problems associated with painful instability of the wrist and forearm after previous resection arthroplasties of the DRUJ. Increasing experience with this procedure and the lasting excellent results over the past 12 years have led us to extend the indication to other pathological processes. As clinical experience demonstrated that stability of the forearm can be restored with this prosthesis, the indications were extended to primarily use the ulnar head replacement in patients with painful osteoarthritis of the DRUJ.

Post-traumatic Osteoarthrosis of the DRUJ

Distal forearm fractures are the most common cause of problems at the DRUJ. Arthroplasty should be considered only if forearm rotation remains painful after the corrective osteotomy or if there is evidence of irreversible joint damage of the DRUJ at the time of the osteotomy. Anatomical alignment of the radius and the ulna is a prerequisite for ulnar head replacement. Any significant radial deformity represents a contraindication for this procedure. In particular, any malunion of the radial or ulnar shaft must be corrected either before or at the time of ulnar head replacement. Mild deformities of the radial metaphysis (10 degrees of dorsal angulation) may be accepted but any more significant or a palmar malangulation of the radial metaphysis requires correction to allow reconstruction of the DRUJ with the ulnar head prosthesis. In patients with significant painful arthrosis of both the radiocarpal and distal radioulnar joints, partial (i.e., radioscapholunate) or complete fusion of the radiocarpal joint and ulnar head replacement may be performed at the same time.

Other Indications

In acute trauma, primary ulnar head replacement may be considered in cases with irreducible, comminuted fractures of the ulnar head requiring ulnar head excision.

Primary osteoarthrosis of the DRUJ is a rare condition but represents an ideal indication for ulnar head replacement because there is no additional DRUJ pathological process that must be addressed at the time of surgery. It frequently affects middle-aged active patients who expect normal performance of the wrist and hand in their professional and private life (Fig. 36-3). The same applies for patients with a giant cell tumor of the ulnar head requiring ulnar head resection.

FIGURE 36-3 A, Radiograph of a 55-year-old patient with painful arthrosis of the DRUJ. B, Radiograph 46 months after primary ulnar head replacement.

The DRUJ is frequently affected in patients with rheumatoid arthritis. I consider ulnar head replacement only in the younger and active rheumatoid patient with the arthrotic or ankylotic type of rheumatoid arthritis, minimal other joint involvement, a stable DRUJ, and a sufficient antirheumatoid medication. Hemi-resection arthroplasty of the DRUJ still represents the best treatment option for the majority of rheumatoid patients because either the insufficient stabilizing soft tissues or the osteoporosis will not allow prosthetic ulnar head replacement, and the patients’ reduced activity level will most probably not lead to symptoms arising from any instability after this procedure.

Another major indication for ulnar head replacement is as a revision procedure in patients with painful instability of the wrist and forearm after previous resection arthroplasties (hemi-resection or complete resection of the ulnar head) or a Sauvé-Kapandji procedure. The long-term experience with this difficult group of patients has proved that reconstruction of the DRUJ using the ulnar head prosthesis is an effective method to cure the problem. However, revision surgery is often difficult and less predictable than when the operation is carried out as a primary procedure. In patients with painful instability after a Sauvé-Kapandji procedure two options for reconstruction are available. Resection of the fusion mass and insertion of the prosthesis is recommended if either the fusion has not healed completely or the original fusion has been performed in an ulnar-positive variance situation leading to additional symptoms of ulna impaction syndrome. In all other cases a spherical head, designed by Fernandez and colleagues,²³ may be used to articulate within the previously fused ulnar head after reaming of a socket into the proximal fusion mass.

Age of the patient as such does not affect my decision for the procedure. In particular, young and active patients with a high demand on the performance of their hand and wrist will most likely develop a symptomatic instability after one of the salvage procedures and therefore benefit from primary reconstruction of the DRUJ using the ulnar head prosthesis. Older patients in their retirement frequently have the same expectations for their private and sport activities. Salvage procedures should therefore be reserved for patients with low functional demands, in whom instability is unlikely to become symptomatic.

Contraindications

Ulnar head replacement is contraindicated in marked osteoporosis or cystic bone disease and whenever the bone quality is inadequate to allow osseous integration of the stem of the prosthesis.

Insufficient soft tissues may result in instability of the DRUJ after reconstruction. Therefore, ulnar head replacement is contraindicated in the majority of rheumatoid patients. It may be contraindicated in patients with severe ligamentous laxity or if several operations have been performed previously. In these patients it has to remain an intraoperative decision of the surgeon, and the patient has to be informed before the surgery that the procedure may not be possible.

Persisting instability or dislocation of the DRUJ after an Essex-Lopresti injury or previous radial head excision is a contraindication for ulnar head replacement because in my experience the distal local soft tissue flap is not suitable to resist the forces in these longitudinal instabilities of the forearm and will lead to recurrence of instability or dislocation at the DRUJ.

DRUJ reconstruction should not be carried out unless any deformity of the radius or ulna has been corrected. This may be performed either before or simultaneously with the ulnar head replacement.

Surgical Technique

Preoperative preparation includes radiographs of the wrist in two planes. In revision surgery, radiographs of the opposite wrist are required to determine the individual ulnar variance. In patients with a history of radial or ulnar shaft fractures or elbow involvement, radiographs of both forearms are required to assess the longitudinal alignment of both forearm bones and to decide whether additional corrective osteotomies are necessary.

Radiographic templates are used to plan the appropriate resection level and implant.

The operation is carried out with the patient in a supine position on the operating table and under tourniquet control. The arm is resting in full pronation on a side table. An image intensifier is required to control the resection level of the ulna, the positioning of the prosthesis, and the ulnar variance at the wrist level during the procedure. Small joint power equipment is required for the procedure.

Primary Ulnar Head Replacement

A slightly curved longitudinal incision is placed directly over the DRUJ and the fifth extensor compartment. The skin flaps are raised off the extensor retinaculum. The sensory dorsal branches of the ulnar nerve are identified and protected throughout the procedure. The fifth and sixth extensor compartments are identified, and the fifth extensor compartment is longitudinally opened along the length of the incision. The extensor digiti minimi (EDM) tendon is mobilized and retracted radially, exposing the dorsal capsule of the DRUJ.

An ulnar-based capsuloretinacular flap is outlined and raised as previously described.^21,^22,²⁴ It includes the extensor retinaculum, the dorsal capsule of the DRUJ, and the sixth extensor compartment, including the extensor carpi ulnaris tendon. The incision is placed along the floor of the fifth extensor compartment and extends from the dorsal shaft of the ulna proximally to the dorsal ulnocarpal joint distally. The dorsal rim of the TFCC is identified, and the flap is carefully raised in one layer along the dorsal radioulnar ligament toward the ulnar styloid process, completely exposing the ulnar head proximally and the ulnocarpal joint distally. The floor of the sixth extensor compartment should be kept intact or repaired to protect the tendon from direct contact with the prosthesis.

At this stage the bone quality and the soft tissue flap are checked. Additionally, the joint surfaces of the DRUJ are inspected to confirm the diagnosis of osteoarthritis and to make the final decision on ulnar head replacement (Fig. 36-4).

FIGURE 36-4 Arthritically destroyed cartilage of the ulnar head.

The hook of the resection guide is now engaged over the distal end of the radius and the resection level, as preoperatively determined using the radiographic template, is marked on the neck of the ulna (Fig. 36-5). With a small power saw the osteotomy is performed perpendicular to the long axis of the ulna.

FIGURE 36-5 Determination of the level of the ulnar osteotomy.

The ulnar head is now grasped with the bone holder and in a combination of blunt and sharp dissection freed from all the connecting tissues. By rotating the ulnar head the underside of the TFCC is exposed and subperiosteally detached from its insertion on the ulnar head. If there is a united fracture of the ulnar styloid, this should be removed.

After removal of the ulnar head the distal ulna is lifted dorsally using the special soft tissue retractor provided. The medullary canal of the ulnar shaft is opened using the broach and then reamed to the appropriate diameter with the hand reamer according to the preoperatively determined size (Fig. 36-6). The reamer should completely fit into the medullary canal to allow later insertion of the shaft of the prosthesis.

FIGURE 36-6 Reaming of the ulnar shaft.

After inspection, the sigmoid notch is cleared of any scar tissue or osteophytes. In rare cases it may be appropriate to deepen the sigmoid notch using a small power bur. Care should be taken not to open the medullary cavity of the radius.

Two drill holes are now placed through the dorsal rim of the sigmoid notch, and strong nonabsorbable sutures are passed to allow later reattachment of the flap (Fig. 36-7).

FIGURE 36-7 Transosseous sutures through the dorsal rim of the sigmoid notch for reattachment of the soft tissue flap.

The inner side of the soft tissue “cap” is now inspected. The roof of this cap consists of the TFCC. Any tear should be closed using fine, nonabsorbable sutures. Should there be a major deficiency or tear of the TFCC, this is repaired by means of either a local flap raised from the palmar capsule or from the extensor retinaculum. The floor of the extensor carpi ulnaris tendon sheath is once again inspected. Any tears that occurred during the bone preparation are sutured. Two fine, nonabsorbable sutures are placed through the dorsal rim of the TFCC, allowing later reattachment to the underside of the flap.

The appropriate trial prosthesis is now inserted and reduced into the sigmoid notch (Fig. 36-8). Seating of the head of the prosthesis within the sigmoid notch as well as the tension of the TFCC over the head in full pronation is now examined. The elbow is now flexed into a 90-degree position, and the position of the prosthesis as well as the ulnar variance is checked using the image intensifier. Radiologically, ulnar variance should measure −1 to −2 mm at the wrist level in neutral forearm rotation. If necessary, the trial prosthesis should be removed and a more proximal resection of the ulna is performed. In case of a too-proximal resection of the ulna with excessive ulnar-negative variance, this can be corrected by reverting to a stem with a built-up collar.

FIGURE 36-8 Insertion of the trial prosthesis and suture for reattachment of the dorsal radioulnar ligament under the soft tissue flap.

The soft tissue flap is now manually advanced over the head of the prosthesis and held down to the dorsal rim of the sigmoid notch. Forearm rotation and stability of the DRUJ are assessed. If the flap is too tight to be attached to the dorsal rim of the sigmoid notch or limits forearm rotation, one should either change to a smaller head size or release the flap. In the case of undue laxity of the flap not allowing stabilization of the DRUJ, a larger head size should be chosen. In these cases ulnar variance has to be reconfirmed radiologically because the larger head will increase the length of the ulna and may require further shortening of the ulna.

After the final determination of the appropriate size of the shaft and head, the arm is rested on the side table again. The definitive prosthesis is implanted using the impactor. The collar of the shaft should completely sit on the distal ulna. Undue forces to implant the shaft should be avoided. If there is any difficulty during implantation, removal of the shaft and further reaming is advised.

The cone end of the shaft is now cleaned to ensure a good interference fit between the two components; then the head is impacted onto the stem (Fig. 36-9).

FIGURE 36-9 Insertion of the definitive prosthesis and the head of the prosthesis on the cone of the shaft.

The elbow is again flexed into a 90-degree position with the forearm elevated and in 30 degrees of supination. The dorsal rim of the TFCC is reattached to the underside of the flap using the previously placed sutures. The flap is advanced and reattached under the appropriate tension to the radius using the transosseous sutures (Fig. 36-10). The repair is completed by suturing the remainder of the flap to the ulnar rim of the extensor retinaculum of the fourth extensor compartment, leaving the EDM tendon subcutaneous.

FIGURE 36-10 Reattachment of the soft tissue flap.

Before insertion of a suction drain and wound closure the stability of the DRUJ and the forearm rotation are assessed. Final radiographs and any necessary adjustments are performed.

Revision Surgery after Resection Arthroplasties

In this situation the operative technique is similar to that of a primary procedure with some exceptions.

In revision surgery, radiographs of both wrists have to be available. Analysis of the radiographs includes a determination of the individual ulnar variance at the wrist level and the amount of length of the distal ulna that has to be covered to create a new DRUJ. With the use of the radiographic templates, a decision needs to be made whether there remains sufficient ulnar length for a standard stem or whether a revision stem will be required (Fig. 36-11). In cases of excessive previous shortening of the ulna a custom-made prosthesis with additional length of the collar of the shaft of the prosthesis may be required.

FIGURE 36-11 Radiographic templates for preoperative determination of the adequate type and size of the prosthesis.

Whenever possible, the skin incision is placed using the scar from previous surgery. The scar tissue from previous surgery makes definition and preparation of the stabilizing soft tissue flap more difficult than in primary surgery, and some of the scar tissue in the resection cavity has to be used to create a solid flap.

In cases in which a revision or custom-made prosthesis is required, the level of resection of the ulna is best determined by laying the trial prosthesis in the correct position alongside the ulna and then marking off the appropriate level for the osteotomy.

The sigmoid notch has to be completely cleared of any remaining scar tissue to allow a stable reduction.

The anatomical structures defining the flap have to be outlined. The TFCC frequently requires reconstruction.

Revision Surgery after Sauvé-Kapandji Procedures

To resolve a painful instability after a Sauvé-Kapandji procedure two options are possible that must be decided on before surgery. Either the arthrodesis of the ulnar head is taken down and a prosthesis is used in a similar manner to that of revision surgery for failed resection arthroplasties or a bony ball-and-socket joint is created underneath the fused ulnar head using the prosthesis with a special spherical head as described by Fernandez and associates.²³

Removal of the ulnar head is indicated in cases in which fusion of the DRUJ has been performed in an ulnar-positive variance situation, leading to additional symptoms of ulna impaction syndrome or if the fusion has not healed completely. In all of these cases a prosthesis with a revision shaft will be required because the previous resection level is far proximal to the neck of the ulnar head (Fig. 36-12). In some cases a custom-made shaft may be required to restore the length of the ulna, which must be determined before the surgery using the radiographic templates. The procedure is performed in a similar manner as that for revising a resection arthroplasty with the following exceptions.

FIGURE 36-12 A, Posteroanterior radiograph of a 39-year-old patient with painful radioulnar impingement and symptoms of ulnar impaction syndrome after a Sauvé-Kapandji procedure. B, Intraoperative photograph after resection of the fused ulnar head, reaming of a new sigmoid fossa, and preparation of the ulnar shaft. C, After insertion of the revision stem of the ulnar head prosthesis. Posteroanterior (D) and lateral (E) radiographs of the same patient 3.6 years after reconstruction of the DRUJ with the ulnar head prosthesis.

Previous surgery is frequently performed using a lateral approach to the ulnar head. In these cases I do not use the scar from the previous surgery but tend to perform the revision using my standard dorsal approach. Creating the soft tissue flap is difficult, and strict subperiosteal dissection of all the soft tissues from the dorsal aspect of the fused ulnar head is advised before resection of the fused ulnar head is performed using small chisels. In cases in which complete fusion of the DRUJ had been achieved, a new sigmoid notch has to be created using small power burs. In cases with incomplete fusion, the sigmoid notch has to be cleared of all remaining osteophytes to create a smooth cavity for the head of the prosthesis. In most patients the TFCC has not been violated from the previous surgery but may be deficient from an ulnar impaction syndrome and require reconstruction.

If the ulnar head has been fused in an anatomical position, stability may be restored by creating a ball-and-socket joint under the fusion mass (Fig. 36-13). A longitudinal incision is placed dorsally over the ulnar head extending proximally to the dorsal aspect of the distal end of the ulnar shaft. The distal end of the ulna as well as the proximal end of the fusion mass is exposed. With the use of a special power reamer a spherical cavity is created underneath the proximal end of the fused ulnar head to later contain the spherical head of the prosthesis. Preparation of the ulnar shaft and determination of the appropriate-sized shaft of the prosthesis is performed in a similar fashion to that of a primary procedure. Because in this procedure bony stabilization rather than soft tissue stabilization is the aim, the spherical cavity will have to cover at least one third of the spherical head of the prosthesis. After implantation of the shaft and impaction of the spherical head on the cone of the prosthesis, reduction of the head into the bony cavity may not be possible. Osteotomy of the radius with additional plate osteosynthesis may be needed after reduction of the prosthesis.

FIGURE 36-13 A, Posteroanterior radiograph of a 67-year-old patient with painful radioulnar impingement after a Sauvé-Kapandji procedure. B, Intraoperative demonstration after insertion of a revision stem of the prosthesis into the ulnar shaft and reposition of the spherical head of the prosthesis under the fusion mass by means of a ball-and-socket joint. C, Postoperative radiograph of the same patient 27 months after the stabilization using the ulnar head prosthesis.

Rehabilitation

The wound and soft tissue repair should be protected from undue strain. Therefore, at the end of the operation an above-elbow plaster splint with the elbow in 70 degrees of flexion, the wrist in 20 degrees of extension, and the forearm in 40 degrees of supination is applied. Active mobilizing exercises for the fingers and the thumb are begun the first postoperative day. The suction drain is removed on the second day after surgery. After 2 weeks the suture material is removed and a forearm “gutter” splint is applied, allowing 40 degrees of pronation and supination. After 6 weeks, radiographs are obtained, the splint is removed, and active as well as passive mobilizing exercises are begun to achieve full forearm rotation. Full unprotected work and activity is allowed after 12 weeks.

Depending on the stability that has been achieved at the end of the operation as well as the quality of the soft tissue repair, this rehabilitation program may be individually modified.

Complications

The following potential complications have been noticed and require particular attention. Most of these complications can be avoided and are due to either wrong patient selection, incorrect planning of the operation, faulty operative technique, or inadequate postoperative immobilization.

Recurrent Instability

The most common cause for this problem is an uncorrected radial deformity, in particular of the radial shaft. The soft tissue flap is not strong enough to overcome a dislocation of the DRUJ caused by a bony deformity.

Failure of the soft tissue flap is most commonly due to improper patient selection. Insufficient soft tissues due to rheumatoid patients or as a result of several previous procedures at the DRUJ represent a contraindication for the procedure. This may need to be determined intraoperatively and may necessitate abandoning the procedure. Choice of the correct-sized head of the prosthesis as well as thorough preparation and repair of the flap are crucial for the success of the operation.

Stem Loosening

This problem might occur in patients with severe osteoporosis, which prevents osseous integration of the shaft of the prosthesis.

Other causes include over-reaming of the stem during the operation or selection of an undersized stem that does not allow primary, press-fit stability of the stem in the ulnar shaft.

Secondary loosening of the stem of the prosthesis has been noticed in cases with persistent dislocation of the DRUJ owing to uncorrected radial deformities. This may be explained by the nonphysiological forces and stress applied on the prosthesis.

Ulnar Impaction Syndrome

This problem can always be avoided and is purely due to faulty operative technique. The aim of the procedure is to achieve a DRUJ with an ulnar-negative variance situation of 1 to 2 mm at the wrist level.

Prolonged Pain after the Procedure

Persistent pain for several months after the procedure has been noticed in patients where reaming of the sigmoid notch down to the subchondral bone had to be performed, in particular after a Sauvé-Kapandji procedure. It frequently correlates with radiological signs of remodeling of the sigmoid notch. These symptoms may persist for several months but have always stopped once the bone remodeling process was finalized.

Results

After the development of this prosthesis I started to perform the previously described procedures in 1995. Initially, and until 1999, I only used the prosthesis as a revision procedure in patients with symptomatic instability after previous resection arthroplasties of the DRUJ. All these patients were followed up radiologically and clinically. The lasting and excellent results in this difficult group of patients, and therefore growing confidence in the performance of this prosthesis, led me to start using it as a primary procedure in the treatment of the destroyed DRUJ. My personal series consists of 76 patients whom I have treated with this method.

Clinical Results

At the last follow-up examination, 16 of my 76 patients had a follow-up period of more than 5 years with a mean of 95 (61 to 124) months. All of these patients had suffered from painful instability after a resection arthroplasty of the DRUJ (Fig. 36-14A,B). Overall function of their hands had significantly improved after reconstruction of the DRUJ, and all patients would have had the operation again. Twelve patients returned to their original profession, and 4 patients retired due to their age. With the use of a visual analog scale (from 0 to 10), pain was found to be remarkably reduced from a mean of 8.7 preoperatively to 2.0 at the latest follow-up. Preoperative grip strength averaged 42% compared with the contralateral side and increased to a mean of 74%. Not only was forearm rotation found to be significantly improved after the procedure from a mean of 126 to 144 degrees, but overall wrist range of motion was found to have improved to a similar amount as well. Overall satisfaction with the outcome of the procedure was found to be very high, with a mean of 8.4 on a visual analog scale from 0 to 10.

FIGURE 36-14 A, Posteroanterior radiograph of a 36-year-old patient 11 years after a hemi-resection interposition arthroplasty and secondary shortening of the distal ulna. B, Transverse loading view of the same patient demonstrating the painful radioulnar impingement. C, Posteroanterior view 6 weeks after DRUJ reconstruction. D, Posteroanterior radiograph 7 months after ulnar head replacement showing bone resorption of the distal ulna under the neck of the prosthesis as well as initial remodeling of the sigmoid notch toward the head of the prosthesis. E, Posteroanterior radiograph 6.3 years after the procedure demonstrating the final remodeling of the sigmoid notch as well as the new bone formation filling the gap under the neck of the prosthesis.

Radiological Results

It is quite normal to find some early bone resorption at the distal end of the ulna under the collar of the prosthesis (see Fig. 36-14C, D). It averaged 2 mm and occurred in 6 of these 16 patients. In 4 patients the resorption area secondarily filled up with new bone over time (see Fig. 36-14E). Additionally, it is common to find some reactive bone remodeling at the sigmoid fossa, and I did notice this in 5 of the 16 patients. These bone reactions were harmless and were found to be completed in all patients after 12 to 18 months. Most importantly, there has been no sign of late loosening of the stem of the prosthesis but obvious osseous integration.

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