41 Total Wrist Fusion versus Denervation for Chronic Scaphoid Nonunion
In a perfect world, if every scaphoid fracture would readily unite following the appropriate treatment, there would be no need for salvage procedures.
In our era of unlimited enthusiasm for limited wrist fusions, other salvage procedures such as wrist denervation or total wrist fusion are often forgotten. These procedures have withstood the test of time and must be considered as valid alternatives. The surgeon, however, must be familiar with the expected outcomes and be well versed in the surgical techniques to achieve consistent results.
▪ Wrist Denervation
In 1966, Wilhelm1 described his technique of complete wrist denervation, which was based on numerous anatomical dissections investigating the innervation of the wrist joint. The principal indications for the procedure were scaphoid nonunions and Kienböck disease. In his study he reported on 14 cases of scaphoid nonunion. Postoperatively 10 of these patients were completely pain free and four had moderate pain. Since then almost 20 studies on wrist denervation have been published, although many combined the procedure with a partial wrist fusion or proximal row carpectomy. The most frequent indication for this procedure was scaphoid nonunion (48% of the studies).2 – 12 More recently Rothe et al13 presented the results of wrist denervation in 46 patients with either a stage II and III chronic scapholunate advanced collapse pattern (SLAC = 10) or scaphoid nonunion advanced collapse (SNAC = 36). Of 32 patients who were available for follow-up, 12 (32%) were pain free at an average follow-up of 6.2 years (range, 2.3 to 11.4 years), and seven reported a significant improvement. Fourteen patients continued to experience pain when load-bearing or with stress. Two patients experienced no analgesic benefit following wrist denervation, and four symptomatic patients underwent wrist arthrodesis at an average of 13.5 months postdenervation. The average postoperative disability of the arm, shoulder, and hand (DASH) score was 17.1. in the SNAC group.
An isolated wrist denervation procedure is best indicated in patients with chronic wrist pain due to a chronic scaphoid nonunion with radiocarpal and midcarpal arthritis with a well-preserved range of motion well exceeding the minimal functional requirements. A denervation may also be combined with other salvage procedures, such as a radial styloidectomy or a partial wrist fusion.
Absolute contraindications will include active infection, complex regional pain syndrome (CRPS), and scaphoid nonunions that are amenable to internal fixation. Relative contraindications would include patients who want a definitive procedure without the risk of needing revision surgery and patients who have no improvement following a preoperative diagnostic nerve block.
Wrist Denervation: Surgical Technique
The technique follows Wilhelm’s original description.1 The procedure is usually performed under regional anesthesia and under tourniquet control using five separate incisions. The first incision ( Fig. 41.1A ) is along the volar radial aspect of the radial styloid between the first extensor compartment and the radial artery. The radial artery is identified and stripped of all adventitia, and a 1 cm section of the venae comitantes is resected. The palmar fascia of the forearm is split radially to the flexor carpi radialis tendon and the pronator quadratus muscle is exposed and retracted proximally. The periosteum of the radius is then cauterized transversally distal to the pronator quadratus muscle up to the distal radioulnar joint. From the same incision deep subcutaneous and epifascial spreading dorsoradially allows for interrupting all small nerve branches, which take off the superficial branch of the radial nerve. Through a second incision ( Fig. 41.1B ), proximal and ulnar to the Lister tubercle, deep to the fourth extensor compartment the posterior interosseous nerve is exposed and resected over a length of 2 cm. The subcutaneous tissue is again undermined to cut all the small nerve branches that are derived from the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve. A third incision ( Fig. 41.1B ) is made at the ulnar border of the wrist over the ulnar head. The dorsal branch of the ulnar nerve is also undermined, and the subcutaneous tissue is separated from the fascia to join the second incision. Through a fourth incision ( Fig. 41.1B ), dorsally at the base of the first interosseous space, the recurrent branch of the dorsoradial nerve of the index finger is severed. Finally, through a fifth incision ( Fig. 41.1B ) over the base of the second and third interosseous space, the corresponding recurrent branches are cut. After hemostasis and simple skin closure a wrist splint is applied for comfort for several days postoperatively, and range of motion exercises are started as early as possible. More recently Berger described a partial wrist denervation consisting of sectioning only the anterior and posterior interosseous nerves for SLAC wrist,14 whereas Dellon resected only the distal portion of the posterior interosseous nerve15 for scaphoid nonunion ( Fig. 41.1C and Fig. 41.2 ).
Wrist Denervation: Author’s Results
In a retrospective study16 we reported the results of denervation for pain relief in 20 patients (19 male, one female) with 21 total wrist denervations due to SNAC wrist grade III. The mean age at the operation was 45.5 years [range 21 to 71 years, standard deviation (SD) 13.3], there were eight right and 13 left wrists (nine at the dominant side) operated. The mean follow-up was 10.8 years (range 1.4 to 23 years, SD 6.5). Four patients needed a second operation (one proximal row carpectomy, three total wrist arthrodeses) due to intractable pain. At the final follow-up five patients were pain free, six had few, six moderate, four considerable, and none extreme pain. Ten patients reported a considerable, three a slight, five a temporary, and three no postoperative improvement. Three patients had to change their profession, whereas the others resumed their former occupations (six heavy worker, six medium heavy worker, five light manual, one administration). Nine patients had no restrictions in their occupation or daily activities, five had little, four moderate, three considerable, and none extreme. The mean DASH score (best: 0, worst: 100) was 23 (range 0 to 49, SD 16). Sixteen patients would repeat the same procedure again, three would not, and one was undecided. There was no correlation of the results with the time of follow-up, and notably there was no deterioration in the favorable results over time.