Arthrodesis

Fig. 1

Dorsal approach 3–4, capsulotomy design

The radiocarpal and midcarpal intervals are examined to exclude a cartilage lesion with subchondral osseous lesion, which – if present – is a contraindication to this arthrodesis. The scapholunate ligament remnants are excised to allow optimal reduction of the scaphoid. Scaphocapitate interval surfaces are freshened down to cancellous bone. Rotatory subluxation of the scaphoid is reduced with a 10/10-mm Kirschner wire introduced into the proximal pole of the scaphoid and used as a ‘joystick’ (Figs. 2, 3 and 5). A temporary scaphocapitate arthrodesis using a 12/10-mm Kirschner wire maintains this reduction. Good scaphocapitate congruence is verified: the radioscaphoid angle should be about 45° on lateral view on intraoperative fluoroscopy.

Fig. 2

Joystick K-wire in the pole of the scaphoid is used for reduction of rotatory subluxation

Fig. 3

Scaphocapitate freshening

A cancellous bone graft is harvested from the radius at the tubercle of Lister after radial corticotomy through the same approach. The graft is used to improve congruence at the arthrodesis interface. The fixation is secured using 2–4 standard or shape memory scaphocapitate staples (Fig. 4). Intraoperative wrist mobilization is done to exclude dorsal conflict with the hardware. A radial styloidectomy may be performed if a styloscaphoid conflict is detected. The capsule and retinaculum are reconstructed. Skin is closed in two planes with a suction drain. The preoperative forearm wrist splint is replaced by a fibreglass splint until radiological consolidation as judged by the surgeon is achieved. This is around 10 weeks. Rehabilitation is then begun.

Fig. 4

Scaphocapitate arthrodesis using bipodal staples

3 Surgical Indications of Scaphocapitate Arthrodesis

In chronic scapholunate instability, a complete description of ligament lesions, cartilage lesions and scaphoid reducibility should be precise and documented by CT arthrogram and arthroscopy. A reducible scaphoid is essential for the success of soft issue stabilization techniques [6] (Fig. 5).

Fig. 5

Restoration of radioscaphoid congruence by scaphoid reduction

Scaphocapitate arthrodesis is indicated in late, fixed chronic scapholunate instability with a scaphoid that is hardly reducible or irreducible. This corresponds to stage 5 in the algorithm of Garcia-Elias et al. [6]. It is also indicated if surgical approaches at the dorsum of the wrist preclude soft tissue procedures. It can also be used after failure of stabilization or failed primary ligament repair. Radioscaphoid arthritis and more advanced arthritis are contraindications to scaphocapitate arthrodesis.

4 Clinical Series

4.1 Material

Our study is retrospective monocentric including 58 scaphocapitate arthrodesis procedures for chronic scapholunate instability performed in our unit between 1999 and 2007. Thirty-one arthrodeses in 30 patients (24 men and 6 women) were reviewed by an independent examiner. Mean age at operation was 43 years (20–65). Mean follow-up was 5 years (8 months–8 years). The dominant hand was affected in 70 % of cases. Distribution of injury mechanisms was as follows: indirect wrist trauma 74 % (23/31) with associated high-energy lesions in 16 % (3 articular distal radius fractures, 1 perilunate dislocation, 1 distal radius fracture with perilunate dislocation), without trauma in 26 % (7/31) and with one case after trapezectomy for basal thumb arthritis. The series included 57 % work accidents. All patients presented with symptomatic chronic scapholunate instability, with 35 % after failed primary ligament surgery – either by attempt at reinsertion or after bone-ligament-bone procedures. The arthrodesis was performed at an average of 25 months after the first surgery (8–72). All patients had clinical and radiological evidence of scapholunate instability. Diagnostic arthroscopy was performed in 23 wrists to exclude a possibility for ligament reinsertion and any contraindication to scaphocapitate arthrodesis as in radiocarpal or midcarpal arthritis. Scapholunate instability was of grade 3 in 61 % and grade 2 in 39 % according to the classification of Dréant and Dautel [7]. The delay between the onset of symptoms and the surgery was on average 15.8 months (1–48). The mean time-off work duration was on average 5.2 months (0–36).

4.2 Method

Follow-up included clinical examination, radiologic and functional assessment.

Bilateral wrist examination was used to compare mobility of the operated wrist to the contralateral one, grip strength and pinch grip using the Jamar dynamometer. Preoperative and follow-up X-rays were used to compare carpal height and index of lateral deviation in the frontal view [8] before and after. Radioscaphoid, radiolunate and scapholunate angles were also compared. The duration of consolidation, the degree of nonunion, radiocarpal or midcarpal arthritis and styloscaphoid conflict were assessed. Complications to the procedure were documented.

Functional assessment was done using DASH and PRWE scores [9].

The PRWE evaluates overall wrist disability more precisely, comparing it to healthy wrist. The patient reports on pain at rest or on activity and the ability of performing specific activities involving the wrist. Values are reported as disability percentages. The time-off work was noted, as well as return to same position versus vocational reclassification.

4.3 Results

Scaphocapitate arthrodesis diminishes wrist mobility (Table 1). Flexion was at 41° (−37 % of contralateral) and extension 39° (−29 %). Radial inclination was limited to 11° (−52 %), and ulnar inclination is at 32° (−18 %). Flexion-extension range was at 80°, and radioulnar inclination was 43°.

Table 1

Scaphocapitate arthrodesis series

	Delay (months)	n-SLI	Follow-up (months)	Age	% TOW	F°	E°	RI°	UI°	Jamar (kg/force)	Nonunion %
Pisano et al. [11]	16	11–4	23.4	32	–	32	42	10	24	29	12
Chantelot et al. [12]	16	13–13	26	40	38	28	48	13.8	25.8	14	23
Saffar [19]	18	33–33	26	39.4	40	37.2	51.3	10.3	29.2	–	15
Delétang et al. [27]	16	31–31	60	43	57	41	39	11	32	32.5	13(8)

Mean grip strength Jamar was 35.5 kg (−19 %), and the pinch grip was minimally affected at 6 kg (−10 %).

DASH score was 27 %. PRWE score showed global disability of 25 % compared to the healthy side. Pain at rest was absent in 50 % of fused wrists and scored 1.5/10 for the other patients. It increased with increased loading or repetitive movements, reaching a maximum of 4/10. Ninety-four percent of patients were satisfied with the procedure and would choose to have it done again. Return to work was 71 % with 22 % professional reclassification. The mean time-off work postoperative was 5.8 months.

Radiologic analysis showed duration of consolidation to be 10.1 weeks postoperative [6–13]. The carpal height and index of deviation on front view were conserved at follow-up – they were normal preoperatively. Radioscaphoid angle went from 60° preoperative to 55° postoperative; the radiolunate angle showed little change, −6° to −9°. The mathematical resultant – the scapholunate angle – showed a small shift from 66° to 63° postoperative.

In 84 % of cases, there was no radioscaphoid arthritis. A radial styloscaphoid conflict was found in 22 % of wrists with little clinical impact. A complementary styloidectomy (same setting) had been performed in 32 % of operated cases to avoid styloscaphoid conflict.

Radiocarpal or midcarpal arthritis was found in 16 % of operated wrists; these had all presented with distal radius fractures +/− perilunate dislocation. Two wrists required an additional palliative procedure: four-corner arthrodesis in one and total wrist arthrodesis in the other due to symptomatic progression of arthritis.

The fixation was performed using bipodal staples with no shape memory in 86 % of cases. A radial cancellous bone graft was used in 81 % of fusions.

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