Management of Pisotriquetral Instability.

Pisotriquetral instability is an often-overlooked condition that can lead to ulnar-sided wrist pain and dysfunction. Various case series and biomechanical studies have been published regarding the diagnosis and treatment of this condition. We review current methods for examining, diagnosing, and treating pisotriquetral instability.

Management of lunotriquetral instability: a review of the literature.

UNLABELLED: Lunotriquetral ligament injury is a relatively common cause of ulnar-sided wrist pain. Injury ranges from partial stable ligament tears to extensive perilunate instability. Clinical decision-making largely depends on the chronicity, instability and cause of the ligament injury. Conservative treatment is generally regarded as first choice of treatment of mild lunotriquetral instability; however, outcome studies on conservative treatment are lacking. Temporary arthroscopic pinning and/or debridement are minimally invasive procedures of preference. In the case of more dissociative injury, surgical interventions may be performed. The literature suggests that soft tissue reconstruction is an effective procedure in this group. Arthrodesis of the lunotriquetral joint is associated with high rates of non-union (up to 57%) and the indications for surgery should therefore be very clear. Methodological issues make it hard to draw firm conclusions from the data. Studies on the effectiveness of conservative management and prospective comparative studies will further improve clinical decision-making in lunotriquetral instability. LEVEL OF EVIDENCE: N/A.

Sex-related shape dimorphism in the human radiocarpal and midcarpal joints.

Previous research has revealed significant size differences between human male and female carpal bones but it is unknown if there are significant shape differences as well. This study investigated sex-related shape variation and allometric patterns in five carpal bones that make up the radiocarpal and midcarpal joints in modern humans. We found that many aspects of carpal shape (76% of all variables quantified) were similar between males and females, despite variation in size. However, 10 of the shape ratios were significantly different between males and females, with at least one significant shape difference observed in each carpal bone. Within-sex standard major axis regressions (SMA) of the numerator (i.e., the linear variables) on the denominator (i.e., the geometric mean) for each significantly different shape ratio indicated that most linear variables scaled with positive allometry in both males and females, and that for eight of the shape ratios, sex-related shape variation is associated with statistically similar sex-specific scaling relationships. Only the length of the scaphoid body and the height of the lunate triquetrum facet showed a significantly higher SMA slope in females compared with males. These findings indicate that the significant differences in the majority of the shape ratios are a function of subtle (i.e., not statistically significant) scaling differences between males and females. There are a number of potential developmental, functional, and evolutionary factors that may cause sex-related shape differences in the human carpus. The results highlight the potential for subtle differences in scaling to result in functionally significant differences in shape.

Anthropometric characteristics of wrists joint surfaces depending on lunate types.

It is well known that the lunate presents with two main types: lunate type I has one facet of its distal surface only for capitates, whereas lunate type II has two facets of the same surface for capitate and for hamate. Our previous anthropometric studies showed that the lunate type II wrists are of greater size than the lunate type I wrists. The aim of the present study was to determine whether the lunate types and the presence or absence of hamato-lunate joint correlate with anthropometric characteristics of the joint surfaces of other wrists. Sixteen sets of macerated wrists with the lunate type I and 21 with the lunate type II were studied. Two-thousand-four-hundred-and-forty-eight anthropometric measurements were done (for 68 anthropometric indicators) and 864 anthropometric indices were calculated (for 24 anthropometric indices) separately for the wrist joint surfaces. The absolute value of the anthropometric indicators of the joint surfaces of the separated wrists were greater in the wrists with the lunate type II, except for the indicators "Greatest length of the dorsal joint surface of pisiform", "Width of the proximal joint surface, measured in the middle" and "Greatest width of the proximal joint surface" for the trapezoid and "Greatest height of the ulnar joint surface" for the capitate. The enlargement of the joint surfaces for the scaphoid was mainly in proximo-distal direction. The enlargement for the triquetrum and pisiform was mainly in radio-ulnar direction. The enlargement for trapezium, trapezoid and capitate was mainly in dorso-volar direction (except for the ulnar joint surface of capitate). The enlargement for hamate was mainly in radio-ulnar and dorso-volar directions (except for the joint surfaces for capitate and triquetrum). The calculated indices illustrate the quantitative proportions of the variations mentioned above. The anthropometric differences are a good reason to make a clear distinction between both types of wrist joint complexes-with or without a hamato-lunate joint.

Visualisation of the pisotriquetral joint through standard portals for arthroscopy of the wrist: a clinical and anatomical study.

Disorders of the pisotriquetral joint are well recognised as the cause of pain on the ulnar side of the wrist. The joint is not usually examined during routine arthroscopy because it is assumed to have a separate joint cavity to the radiocarpal joint, although there is often a connection between the two. We explored this connection during arthroscopy and in fresh-frozen cadaver wrists and found that in about half of the cases the pisotriquetral joint could be visualised through standard wrist portals. Four different types of connection were observed between the radiocarpal joint and the pisotriquetral joint. They ranged from a complete membrane separating the two, to no membrane at all, with various other types of connection in between. We recommend that inspection of the pisotriquetral joint should be a part of the protocol for routine arthroscopy of the wrist.

An anatomic study of the triquetrum-hamate joint.

PURPOSE: To investigate the articulating surface of the triquetrum-hamate joint (TqH). METHODS: The carpal bones of 46 wrist specimens were examined. The shape of the TqH joint surfaces were investigated, with focus on variations in the shape of the hamate and corresponding triquetrum and the presence and position of convex and concave surfaces. RESULTS: Two distinct patterns of hamate TqH articular surfaces were identified, designated type I (31 of 46) and type II (15 of 46). The triquetral TqH articular surface also was found to have 2 distinct patterns, designated type A (18 of 46) and type B (15 of 46). Of the triquetrums examined 13 of 46 had characteristics that were a variable mixture of the 2 identifiable triquetral surface types, but these did not have sufficient similarity to constitute a third triquetrum surface type. The corresponding articulation patterns of these joint surfaces showed a strong trend for a type A triquetrum to articulate with a type I hamate (18 of 46 of all joints) and for a type B triquetrum to articulate with a type II hamate (13 of 46 of all joints). No association was seen between lunate types and type I or type II hamates. CONCLUSIONS: These findings suggest the existence of 2 distinct TqH joint patterns, which have been termed TqH-1 and TqH-2. There appears to be a spectrum of variation between these 2 identifiable types. As a result, the TqH is best described as a spectrum, with TqH-1 at one end and TqH-2 at the other. A TqH-1 joint is a helicoidal configuration. It is double-faceted, with the hamate and the triquetrum articular surfaces possessing complementary concave and convex parts. A TqH-2 joint has a predominantly oval convex shape, whereas the primarily concave triquetrum is better described as a dish for the flatter hamate. It has no hamate groove or distal ridge.