What Is Midcarpal Instability (Wrist Instability)?

Mid-Carpal Instability: www.wheelessonline.com/ortho/mid_carpal_instability & wristinstability.multiply.com/journal/item/3

*patients may note wrist clicking and pain while lifting heavy objects;

*grasping in supination may provoke symptoms;

*symptoms may include tenderness over lunocapitate and triquetrohamate joints;

*the later is thought to be the more affected joint;

*painful audible snap often results from active ulnar deviation w/ forearm pronation;

*the flexion subluxation of the proximal carpal row causes the reduction clunk (proximal row extension) as the wrist moves into ulnar deviation;

*some loss of palmar flexion is usually present;

*grip strength can be decreased by as much as 50%;

*ref: Quantitative assessment of the midcarpal shift test.<br><br>Post edited by: Scott_1984, at: 2009/02/08 09:54

Ulnar midcarpal instability-clinical and laboratory analysis (September 1981): lib.bioinfo.pl/pmid:7276484

Patients with ulnar midcarpal instability have a characteristic pattern of clinical signs and symptoms related to the midcarpal joint.

The usual presenting complaint is a painful wrist click which can be reproduced by ulnar deviation, axial compression, and pronation of the wrist.

Routine x-rays are usually normal, but cinefluoroscopy reveals sudden dissociation between the proximal and distal carpal rows resulting in a dorsiflexion collapse deformity.

In six of our patients, conservative therapy sufficed to relieve symptoms.

Four other patients required surgical stabilization.

We close to stabilize the triquetrohamate joint because it was a relatively easy procedure and eliminated instability in most instances.

Laboratory studies aided in understanding the pathomechanics of midcarpal instability, which consisted of dorsal subluxation of the capitate and hamate on the lunate and triquetrum.

We believe that midcarpal instability is not a rare condition but may often be confused clinically with more common carpal dissociations.

A Clinical Analysis of Pathomechanics of Extrinsic Midcarpal Instability (1999): sciencelinks.jp/j-east/article/200012/000020001200A0235739.php

Abstract: sciencelinks.jp/j-east/article/200012/000020001200A0235739.php

There has recently been increasing interest and recognition regarding the midcarpal instability (MCI).

MCI is classified into three types, that is palmar MCI, dorsal MCI, and extrinsic MCI (EMCI) with a Z deformity of the carpus after Colles' fracture. The purpose of this study is to clarify the pathomechanics of EMCI clinically.

In 3 cases with clinical findings of EMCI we observed movement of the carpus by cineradiography, comparing with normal wrist joints and those with malunited distal radius fracture.

The range of motion of the wrist is almost normal after Colles' fracture with EMCI.

The average age of patients with EMCI was younger than that of malunited fractures without wrist instability.

There was no relationship between the occurrence of EMCI and severity of malalignment of the distal radius.

In EMCI the cineradiography of the lateral view in maximum ulnar deviation showed that the lunata rapidly dorsiflexes and shifts in the palmar direction considerably, and the capitate simultaneously shifts in the dorsal direction.

On the other hand, the motion of the lunate was small in malunited cases without wrist instability.

These clinical findings suggest the rupture and laxity of the palmar carpal ligaments in EMCI.

We concluded that the pathomechanics of EMCI are the major change of the distal radius with severe dorsal tilt and the dorsiflexed position of the lunate with palmar translation in ulnar deviation.

In this position, the capitate translates dorsally for the ruptured and lengthened palmar ligament.

The axis of the capitate is not colinear with the lunate, and sudden clicks or painful subluxation occurs. (author abst.)

Ulnar-Sided Wrist Pain: www.emedicine.com/orthoped/topic619.htm

INTRODUCTION: www.emedicine.com/orthoped/topic619.htm

Wrist pain often proves to be a challenging presenting complaint.

Determining the cause of ulnar-sided wrist pain is difficult, largely because of the complexity of the anatomic and biomechanical properties of the ulnar wrist.

The objectives of this article are to provide an overview of the most common problems encountered in the diagnosis of ulnar-sided wrist pain and to review anatomy, diagnostic modalities, clinical presentation, and various treatments available.

Over the last several years, great advances have occurred in imaging techniques.

Although these imaging techniques are often invaluable, at times they are expensive and unnecessary.

The majority of diagnoses involving ulnar wrist pain may be established with detailed history taking, thorough physical examination, and standard radiography.

When a diagnosis cannot be established by using the standard methods, more advanced diagnostic modalities should be considered.

For excellent patient education resources, visit eMedicine's Hand, Wrist, Elbow, and Shoulder Center: www.emedicinehealth.com/script/main/art.asp?articlekey=60053

Also, see eMedicine's patient education article Wrist Injury: www.emedicinehealth.com/wrist_injury/article_em.htm

ABSTRACT: www.orthosupersite.com/default.asp?page=view&rid=2392

The evaluation of chronic wrist pain can be a diagnostic dilemma.

Lidocaine injections combined with corticosteroids often are used for therapeutic and diagnostic purposes.

This study determined whether a midcarpal injection of lidocaine could serve as a diagnostic tool in patients with chronic wrist pain.

Specifically, the relationship of pain relief from the injection and improvement of grip strength were compared to intracarpal pathology as confirmed by wrist arthroscopy.

Forty-five patients with chronic wrist pain underwent a midcarpal injection of lidocaine with or without corticosteroids.

Improvement of pain and improvement of grip strength were determined. Each patient subsequently underwent a radiocarpal and midcarpal arthroscopy, and the pathologic findings of arthroscopy were compared to the improvement of pain and grip strength.

These data were compared to a cohort of six volunteers without history of wrist pain or trauma who underwent midcarpal injection of lidocaine.

Statistical analysis was performed using Receiver-Operator-Characteristic analysis.

The average age of patients with chronic pain was 30.3 years, with an average of 9.8 months of wrist pain.

The ultimate diagnoses included carpal dissociative instability (n=35), nondissociative instability (n=2), complex instability of the carpus (n=7), extensor carpi ulnaris tendinitis (n=3), and deQuervain's tenosynovitis (n=1).

After lidocaine injection, the normal cohort had a mean loss of 2 kg (25.3%) (P=.02) in grip strength whereas the experimental cohort had a mean improvement in grip strength of 5.73 kg (34.4%).

Improvement of pain after injection did not correlate with pathologic arthroscopic findings (P=.92).

Improvement in grip strength after midcarpal lidocaine injection of 6 kg or 28% had a 73% sensitivity and 70% specificity (P=.02) of having intracarpal pathology at arthroscopy.

Of the chronic wrist pain patients, only 4 had a normal arthroscopy, and the remainder had at least 1 area of significant pathology attributing to their pain.

A midcarpal injection of lidocaine serves as an effective diagnostic tool in the evaluation of patients with chronic wrist pain.

A 28% improvement of grip with or without pain relief is highly correlated with intracarpal pathology. www.orthosupersite.com/default.asp?page=view&rid=2392

Quantitative assessment of the midcarpal shift test:

The subjective, clinical midcarpal shift test was compared with a quantitative measurement of carpal volar/dorsal translation versus ulnar deviation using a mechanical testing system.

Testing was performed on 19 healthy volunteers (mean age, 33 years) and 3 patients (four wrists; mean age, 23 years) who had been diagnosed with ulnar midcarpal instability, a nondissociative form of carpal instability.

During physical examination, each subject's wrist was graded I to V using the previously described classification of the degree of laxity and clunk observed with the midcarpal shift test.

Each subject was also evaluated using a quantitative mechanical testing system that simulates the subjective clinical test.

The testing system measures displacement of the distal carpal row, more specifically, the capitate, as the wrist is moved from neutral to ulnar deviation under a constant axial load of 44 N directed volarly at the head of the capitate.

Reflective markers were attached to the skin above the proximal and distal ends of the third metacarpal and at the point where the 44-N load was applied to the carpus.

Motion of the markers was used to calculate ulnar deviation and dorsal/volar translation of the carpus.

The maximum slope of the carpal translation versus ulnar deviation curve was measured for each subject and compared with the results of the clinical midcarpal shift test.

Higher maximum slopes were seen in subjects with the higher grades of carpal laxity.

There were also differences with regard to the point at which the clunk occurred; the higher the clinical grade of laxity, the greater the ulnar deviation of the wrist at the point at which the clunk was observed.

These differences were not significant, however.

These data confirm the validity of the clinical test and establish its usefulness as a diagnostic indicator of midcarpal nondissociative carpal instability.

The mechanized test also may be useful as a biomechanical marker, enabling the results of ligament sectioning to be effectively compared with defined clinical laxity.