Although midcarpal instability was first described almost 45 years ago, this uncommon condition is still poorly understood by most clinicians today. Adding to the confusion, it is known by 2 different names: midcarpal instability and carpal instability nondissociative. In this article, we describe the history of the recognition of instability of the midcarpal joint, including its pathomechanics, classification, and treatment. We hope that a more complete understanding of the etymology and kinematics of the disorder will facilitate its future recognition and assist in appropriate treatment decision making.

Variation in lunate morphology can exist based on the absence (Type I) or presence (Type II) of medial facet on the distal articular surface of the lunate that contacts the proximal pole of the hamate. This additional lunatohamate articulation can affect load transmission across the radiocarpal joint and exert an influence on carpal kinematics. A Type II lunate is protective against carpal instability patterns associated with scaphoid nonunions and scapholunate dissociations. It may also play a role in the progression of carpal collapse that occurs in Kienböck disease. This review summarizes the effect of lunate morphology in the outcomes of non-operative and operative treatment of carpal disorders.

METHODS: Scoping review.
BACKGROUND: Dart thrower\'s motion (DTM) of the wrist primarily arises from the midcarpal joint, and minimizes stress to the scapholunate interosseous ligament (SLIL). After SLIL injury or surgery, early controlled DTM may reduce the effects of prolonged immobilization, while protecting SLIL integrity.
OBJECTIVE: To summarize the literature on the effects of DTM on the injured and surgically repaired SLIL and the extent to which various DTM orthotic designs promote SLIL recovery.
METHODS: A systematic literature search was conducted within 6 databases for articles published between 2003 and March 2018. Eligible studies examined DTM in the context of SLIL injury or repair. Relevant data were extracted by 2 independent reviewers.
RESULTS: Of 425 identified articles, 15 were eligible for inclusion. Five biomechanical studies examined the influence of DTM on the injured SLIL, whereas 5 articles described DTM orthotic designs. Also included were five articles that reported outcomes when DTM was used in the rehabilitation protocol.
CONCLUSIONS: The included studies suggest limiting end ranges of DTM in the injured/repaired SLIL, while blocking orthogonal plane movements. Custom orthotic designs may accomplish this goal. DTM has been used in comprehensive therapy programs in small case studies reporting short-term and intermediate clinical outcomes.
CONCLUSIONS: Caution should be exercised with using DTM on the torn SLIL as gap increases, particularly at the end-range motion. Orthosis designs have potential to limit this motion to midrange, while allowing early movement. Further high-level research is needed to understand the influence of DTM on injured and postsurgical populations.

Background: The purpose of this study was to identify factors associated with unplanned reoperation after surgery for scapholunate interosseous ligament (SLIL) insufficiency. Methods: Using Current Procedural Terminology (CPT) codes from 3 hand surgery centers across 2 metropolitan areas, we identified 316 patients undergoing surgery for SLIL insufficiency from 2000 to 2014. Medical records were manually reviewed to collect data on factors that might be associated with unplanned reoperation, including age, sex, tobacco use, occupation, acuity of treatment, and reconstruction method. Results: Thirty-eight patients (12%) had an unplanned reoperation; most of them (65%) were a secondary reconstruction or salvage procedure (eg, 6 proximal row carpectomies, 9 revision reconstruction, and 10 partial carpal arthrodeses), while 5 (13%) were for unplanned screw removal. The median time between the index and second surgery was 16 months (range, 2-97 months). The type of index procedure was not associated with reoperation. The only factor associated with reoperation was cigarette smoking, and this association persisted when looking specifically at reoperations for revision or salvage. Conclusions: Patients should be counseled that smoking is associated with reoperation after SLIL surgery. Smoking cessation or decreasing nicotine usage may be beneficial prior to surgery. With the numbers available, there was no association between surgical technique and reoperation.

Scapholunate (SL) instability is the most common dissociative carpal instability condition. It is the most frequent cause of wrist osteoarthritis, defined as scapholunate advanced collapse or SLAC wrist. Familiarity with the SL ligament complex is required to understand the various features of SL instability. Damage to the SL interosseous ligament is the main prerequisite for SL instability; however the extrinsic, palmar and dorsal ligaments of the carpus also come into play. When more than 6 weeks has passed since the initial injury event, SL instability is considered chronic because ligament healing is no longer possible. Before osteoarthritis sets in and when the SL instability is still reducible (scaphoid can be reverticalized), ligament reconstruction surgery is indicated. Since the end of the 1970s, various ligament reconstruction or tenodesis techniques have been described. These techniques are used in cases of chronic, dynamic or static reducible SL instability, when no repairable ligament stump and no chondral lesions are present. The aim is to correct the SL instability using a free or pedicled tendon graft to reduce pain while limiting the loss of mobility and protecting against osteoarthritis-related collapse in the long-term. We will perform a systematic review of the various tenodesis techniques available in the literature.

The aim of this study was to analyse lunate fractures and any associated osseo-ligamentous injuries. A systematic review identified 34 cases. We identified carpal instabilities at the radiocarpal and midcarpal joints in volar and dorsal directions. Radiocarpal instabilities (10/34) were usually dorsoradial (8/10), with a transverse lunate fracture, best seen on a coronal image. Midcarpal instabilities (24/34) were usually volar (14/18), with a volar lunate shear fracture, best seen on a sagittal image. Instabilities were sub-classified into non-displaced, subluxated and dislocated. Associated fractures of the scaphoid and the radial and ulnar styloid processes were common. Lunate fractures without subluxation or dislocation had good outcomes with cast immobilization or fixation of associated fractures. Lunate fracture-subluxations are unstable injuries that are best managed with fixation of the carpal fractures. Lunate fracture-dislocations are complex injuries, requiring stabilization of the lunate, associated fractures and ligament injuries; complications are common and acute or delayed salvage procedures may be required.

Dislocation of all 5 carpometacarpal (CMC) joints of a single hand is a rare injury.
The literature regarding CMC fracture-dislocations was reviewed and a case was presented.
The relevant literature was consolidated to clinically relevant categories including \'Clinical Presentation and Diagnosis,\' \'Management of CMC Fracture Dislocation and Hamate Fractures,\' and \'Outcomes.\'
The mechanism associated with this injury is often high energy that causes multiple simultaneous life- or limb-threatening injuries that could distract the examiner from identifying this injury. The case we present involves an axial dislocation of the carpus that resulted in dorsal dislocations of all CMC joints, dislocation of the hamate-capitate articulation, as well as fractures of the first metacarpal and the hamate.

The management of scaphotrapeziotrapezoidal (STT) joint osteoarthritis (OA) remains controversial. This systematic review aims to review the evidence for surgical interventions specific to STT OA.
Medline and Embase libraries were searched using a pre-defined search strategy in October 2014. All study designs and languages were included and evaluated by two reviewers (VMD and LM) against the inclusion/exclusion criteria. The study eligibility criteria included papers discussing surgical treatment of STT OA, and the review was conducted using the PRISMA guidelines.
295 unique results were identified from the search strategy after duplicates were filtered. 21 articles met the eligibility criteria.
Trapezial excision and partial trapezoidal excision is an effective treatment with low morbidity and complications, although can lead to weakness of the thumb. Distal scaphoid excision remains an effective pain relief treatment with improved grip and pinch strengths post-operatively. The procedure is technically less demanding than arthrodesis, does not carry the risks of non-union and complication rate of STT joint arthrodesis, and has a shorter immobilisation requirement. It produces reliable results, but is contraindicated if there is either scapholunocapitate pathology or midcarpal instability. STT joint fusion has a place, typically producing 75% range of movement of the non-operated wrist. However it has a higher associated complication rate, and simultaneous radial styloidectomy is recommended to reduce ongoing pain from impingement. Implant arthroplasty using a graphite-coated pyrocarbon implant has been used more recently. The patients gained significant pain relief, although there have been reports of implant dislocation secondary to surgical errors. A reduction in post-operative wrist extension and radial deviation has been noted. From this systematic review, we have composed a treatment algorithm for the surgical management of STT joint OA.

Scapholunate reconstruction procedures are best stratified according to preoperative stages of dissociative instability, injury chronicity, and arthrosis. In general, procedures aimed at correcting scapholunate instability focus on reestablishing ligament continuity in order to normalize carpal biomechanics; however, many existing interventions have shown differential success when performed on patients with varying stages of instability and degrees of carpal malalignment. The Mayo dorsal intercarpal ligament capsulodesis has proven most effective for preserving range of motion, whereas the Blatt capsulodesis has been associated with substantial improvements in terms of the postoperative pain rating and perceived functional capacity.

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.
METHODS: N/A.