Chapter 13 Arthroscopic Lunotriquetral Arthrodesis and Head of the Hamate Resection

10.1055/b-0035-121123

Chapter 13 Arthroscopic Lunotriquetral Arthrodesis and Head of the Hamate Resection

Introduction

Lunotriquetral arthrodesis is a controversial procedure but is sometimes proposed as a last resort for lunotriquetral instability. The standard open procedure has a nonunion rate of nearly 50% and leads to persistent pain in 50% of patients. Lunotriquetral arthrodesis is not well suited to wrists with positive ulnar variance or with a Viegas type II lunate due to changes induced in the triquetrum’s biomechanics and its mobility within the first row of carpal bones.1–3

The minimally invasive nature of an arthroscopic procedure can improve outcomes in several ways:

It minimizes capsule detachment, thereby sparing the local vasculature that is indispensable for fusion of the arthrodesis.
It allows the evaluation of any chondromalacia secondary to positive ulnar variance, which can be corrected through arthroscopic distal ulnar resection (Chapter 12) during the same procedure.
It allows other commonly associated injuries (triangular fibrocartilage complex [TFCC], hamate chondritis, synovial chondromatosis, etc.) to be treated.
It guides dynamic analysis of the radiocarpal and midcarpal joints once the arthrodesis has been performed, which allows the surgeon to treat any impingement with the ulnar head or head of the hamate by resecting the latter structure.

Operative Technique (Fontes)

Patient Preparation and Placement

The patient is placed in the standard position with the arm secured to the table. Regional anesthesia and a tour-niquet are used. Finger traps apply 5–7 kg of traction along the arm’s axis.

Radiocarpal Exploration

Radiocarpal joint exploration requires use of the 3–4 portal for the arthroscope and the 6R portal for the arthroscopy instruments. Any inflamed synovial tissue is removed, and the lunotriquetral ligament is inspected for damage. The arthroscope may need to be moved to the 6R portal for a better view of the ligament. The TFCC is also inspected, and the presence of positive ulnar variance or associated ulnar impaction syndrome is determined. If found, treatment is carried out through arthroscopic resection using the standard technique (Chapter 12).

Midcarpal Exploration

The arthroscope is moved into the midcarpal joint through the radial midcarpal (MCR) portal. Lunotriquetral instability is evaluated before this procedure, which is reserved for the most advanced stages of instability (Geissler stages 3 and 4). It is often necessary to excise reactive synovial tissue, or even to carry out arthrolysis to expose the damaged interosseous space ( Fig. 13.1 ). A radiofrequency probe can be useful during this step, along with a small-diameter, aggressive cutter used in the oscillating mode.

Analysis of Lunate Shape and Head of the Hamate Resection in Viegas Type II Wrists

In the next phase of the procedure, the lunate’s shape must be determined based on the presence or absence of an articular facet for the head of the hamate1 ( Figs. 13.2a, b and 13.3a, b ). A type I lunate does not articulate with the hamate; as a consequence, the head of the hamate very rarely develops osteoarthritis, and its shape does not interfere with lunotriquetral arthrodesis. A type II lunate has an extra-articular facet for the hamate; as a consequence, the head of the hamate can become arthritic (this is often found in golfers) ( Fig. 13.4 ). This extra facet interferes with fusion between the lunate and triquetral. The presence of lunohamate chondromalacia can also be the result of excessive pressure in the medial aspect of the wrist due to congenital or acquired positive ulnar variance. In this patient, the damaged head of the hamate must be resected using a small rotating bur inserted through the ulnar midcarpal (MCU) portal, with the scope in the radial midcarpal (MCR) portal ( Fig. 13.5 ).

**Fig. 13.1** Arthroscopic view of lunotriquetral instability. The probe passes easily between the lunate and triquetral.

**Fig. 13.2a, b** Drawing (a) and arthroscopic view (b) of a Viegas type I wrist where the distal lunate is evenly rounded. C, capitate; H, hamate; L, lunate; P, triquetrum.

**Fig. 13.3a, b** Drawing (a) and arthroscopic view (b) of a Viegas type II wrist where the lunate has a distal medial facet that articulates with the head of the hamate. C, capitate; H, hamate; L, lunate; T, triquetrum.

Systematic excision of the head of the hamate in Viegas type II wrists circumvents the need for a bone graft during lunotriquetral arthrodesis. This reduction in the transverse diameter of the first row has no effect on the midcarpal joint.

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