Arthroscopic Ligament Plication for Palmar Midcarpal Instability

Introduction Palmar midcarpal instability (PMCI) is a painful condition characterized by a kinematic dysfunction of the proximal carpal row (PCR). Although its etiology is still poorly understood, it is believed to be due to congenital (or traumatic) laxity of the ligaments that stabilize the PCR, primarily, the dorsal radiotriquetral (DRT) ligament and the ulnar arm of the palmar arcuate ligament. This laxity causes an unphysiologic coupling of the midcarpal joint, which is clinically evident as a painful clunk with ulnar wrist deviation. Most symptomatic PMCI patients benefit from nonoperative management, which is based on splinting and proprioceptive neuromuscular rehabilitation. However, patients that do not respond to nonoperative management are candidates for surgical treatment. Cases with mild to moderate symptoms may be treated with soft tissue procedures, such as dorsal capsular reefing (Lichtman, 2006) or arthroscopic shrinkage (Mason, 2007; Lichtman, 2003). The purpose of this study was to present our results with a personal technique of arthroscopic ligament plication (ALP) for PMCI.

Materials and Methods The technique is performed with a standard wrist arthroscopy setup and consists of dorsal and palmar ligament plication at the radiocarpal joint. The dorsal ALP is a modification of Lichtman's dorsal capsular reefing, in which the DRT and dorsal intercarpal (DIC) ligaments are tightened with two stitches of strong, nonresorbable sutures, instead of being divided and re-sutured as originally described. In cases showing evident carpal pronation and ulnar sag, ALP of the proximal part of the ulnar arm of the palmar arcuate ligament, that is, the palmar ulno-carpal ligaments, is also performed (modified all-inside Savoie technique). The patient is placed in a short arm cast for three to four weeks, then an intensive proprioceptive rehabilitation program is started, including use of dynamic splinting that restricts mobility of the PCR to the plane of the dart throwing motion only for an additional four weeks.

Results Seven patients (4 male, 3 female; ages 20 to 29) complaining of painful PMCI that was unresponsive to conservative treatment, have been operated on since 2008. At an average follow-up of 1.7 years, the Mayo Modified Wrist score was excellent in two cases, good in 4, and fair in 1. Clinical complaints were relieved in all patients. All but one patient returned to heavy work. None of the patients required further surgical treatment.

Conclusion Our results suggest that ALP may be an effective option of treatment for PMCI. On a medium term follow-up, ALP was shown to restore stability of the PCR, with the advantages of a minimally invasive procedure, resulting in slight loss of motion and patient satiscfaction. We suppose that restoration of stability of the PCR is due not only to the direct mechanical effect of ligament tightening, but also to a concurrent dynamic effect produced by the stimulation of the mechanoreceptors located in the DRT and DIC. The DRT and DIC are among the most innervated ligaments of the wrist, with an abundance of mechanoreceptors, including Ruffini receptors and the so-called ”Golgi-tendon-like organs.” Both types of mechanoreceptor react to changes in tensile strain rather than compressive forces, thus, they are in need of ligaments with normal tensile characteristics to function properly. In joints with increased ligament laxity, such as in PCMI wrists, the proprioceptive function is disturbed. The ALP increases mechanical stability of the PCR and is effective in reducing symptoms of PMCI by enhancing the conscious neuromuscular control of the wrist, thereby facilitating proprioceptive reeducation of the wrist.