What Is Midcarpal Instability (Wrist Instability)?

What Is Midcarpal Instability (Wrist Instability/Carpal Instability)?:

Effects of Carpal Instability

Abstract: \"This review addresses the pathoanatomical basics as well as the clinical and radiological presentation of instability patterns of the wrist.

Carpal instability mostly follows an injury; however, other diseases, like CPPD arthropathy, can be associated.

Instability occurs either if the carpus is unable to sustain physiologic loads (\"dyskinetics\") or suffers from abnormal motion of its bones during movement (\"dyskinematics\").

In the classification of carpal instability, dissociative subcategories (located within proximal carpal row) are differentiated from non-dissociative subcategories (present between the carpal rows) and combined patterns.

It is essential to note that the unstable wrist initially does not cause relevant signs in standard radiograms, therefore being \"occult\" for the radiologic assessment.

This paper emphasizes the high utility of kinematographic studies, contrast-enhanced magnetic resonance imaging (MRI) and MR arthrography for detecting these predynamic and dynamic instability stages.

Later in the natural history of carpal instability, static malalignment of the wrist and osteoarthritis will develop, both being associated with significant morbidity and disability.

To prevent individual and socio-economic implications, the handsurgeon or orthopedist, as well as the radiologist, is challenged for early and precise diagnosis.\&quot;<br><br>Post edited by: Scott_1984, at: 2009/02/08 09:41

Understanding Mid Carpal Instability/Palmar Midcarpal Instability (MCI/PMCI)

The concept of midcarpal joint instability (MCI) has evolved slowly since it was first described by Mouchet and Belot1 in 1934.

Subsequent researchers have not agreed about whether the differing personal observations of MCI represent distinct clinical entities or rather different manifestations of the same (or very similar) conditions.

Lacking unanimity in regard to the etiology and pathomechanics of this disorder it is easy to understand why there is also a lack of agreement on terminology and treatment for instability of the midcarpal joint.

Even the name “midcarpal instability” is not accepted universally as the proper designation for this condition.

It is hoped that this review has provided a sufficient overview of the subject to enable the reader to see some common integral threads in the published material and to encourage investigators to accelerate the process of clinical and biomechanical verification of the various published observations regarding MCI.

Unless this process begins soon and leads to a more scientific approach we will continue to rely for many years on a very hazy picture of MCI when trying to determine the appropriate diagnosis and treatment options in the clinical setting.<br><br>Post edited by: Scott_1984, at: 2009/02/08 09:46

Master Skills: Wrist and Elbow Arthroscopy and Reconstruction: CHAPTER 13: Midcarpal Instability:

Master Skills: Wrist and Elbow Arthroscopy and Reconstruction: CHAPTER 13: Midcarpal Instability:

The first description of a “snapping wrist,” diagnosed as anterior midcarpal subluxation,1 was recorded in 1934, although “dorsal luxation of the capitate” had been presented in a congress in Paris in 1919.

However, it was Lichtman’s2 paper in 1981 that brought this particular condition to the attention of our profession.

Of all the forms of carpal instability, midcarpal instability (MCI) has been the most confusing.

The two main reasons for this are that MCI is a mixed bag of conditions and that their

pathophysiology is not well understood.

The management of MCI remains controversial.

The term MCI covers a range of conditions characterized by a painful clunk, usually felt in ulnar deviation of the wrist.

It has been suggested that the term “instability of the proximal carpal row” would be a more accurate description,3 since the mechanical problem is a carpal instability nondissociative (CIND), affecting the radiocarpal or the midcarpal joints or both.

The scaphoid, lunate and triquetrum move like one unit, but not in a predictable smooth manner.

Most patients with MCI respond to nonoperative treatment.

Combinations of immobilization, splints, anti-inflammatories, activity modification and exercise have been prescribed with diverse success.

Surgical treatment suggested for MCI includes soft tissue stabilizations, limited carpal arthrodesis, corrective osteotomies and arthroscopic thermal capsulorraphy.

The role of propioception in carpal instability is starting to be recognized, but again is not yet fully understood.

What Causes the Clunk?:

Clunking of the wrist can be caused by congenital laxity of the wrist ligaments, bone or joint dysplasia, lunotriquetal injury, distal radius malunion or insufficiency of the extrinsic ligament affecting the radiocarpal or the midcarpal joint, or both.

In a normal wrist during radial deviation, the proximal carpal row goes into flexion, and during ulnar deviation it extend in a smooth transition (Figure 1a).

In a wrist with palmar MCI, the proximal carpal row will remain flexed during ulnar deviation, causing a subluxation at the midcarpal joint and, at a certain point, will jump from flexion to extension.

This causes the so called “catch-up clunk” felt by the patient and often clearly seen and heard by observers (Figure 1b).

Midcarpal Instability CHAPTER 13:

This paper as kindly been supplied by:

The Pulvertaft Hand Centre,
Derbyshire Royal Infirmary,
London Road,
Derby,
DE1 2QY,

I'd like to say a \&quot;BIG THANK YOU\&quot; to: Mr Tommy Lindau MD, PhD-Consultant Hand Surgeon &amp; Carlos Heras-Palou, MD, for allowing me to publish this Midcarpal Instability Chapter on my website.

wristinstability.multiply.com/notes/item/6 & msngroup.aimoo.com/PalmarMidcarpalInstabilityPMCIRSD

Post edited by: Scott_1984, at: 2009/02/08 09:52

Mid Carpal Instability (MCI)/Palmar Midcarpal Instability (PMCI) also known as:

Ulnar Midcarpal Instability,
CLIP-Wrist,
Wrist Instability,
Capitolunate Instability Patterns,
Capito Lunate Instability Pattern,
Ulnocarpal Instability,
Midcarpal Instability,
Mid Carpal Instability (MCI),
Palmar Midcarpal Instability (PMCI),
Wrist Pain,
Carpal Instability,
Inter-Carpal Instability,
Scaphoid Instability,
Capitolunate Scaphoid Instability,
Wrist Sprains,
Wrist Sprain,
Ulnar-Sided Wrist Pain,
Ulnar Wrist Pain,
MCI/PMCI,
MCI,
PMCI,<br><br>Post edited by: Scott_1984, at: 2010/05/16 00:37

Carpal Instability: www.maitrise-orthop.com/corpusmaitri/ort...3_saffar/index.shtml

There is no muscular attachment to the proximal carpal row.

It is an intercalated segment stabilized only by ligaments.

Proximal carpal row motion is the consequence of movements of the distal carpal row and forearm bones.

The intracapsular wrist volar ligamentous plane is thick and strong (Fig 1): stretching of this structure is difficult to assess but probably plays a role in carpal instability.

The dorsal ligamentous plane is thinner and less important for carpal stability.

Description of the “carpal instability” entity is more than 25 years old (Linscheid et Dobyns, 1972).

It was defined as carpal malalignment on X-rays or by carpal ligamentous tears and controversy still exists regarding this definition.

We have been interested in pathology of carpal instability since it was described.

New imaging techniques for the carpus have helped the surgeons to pre-operatively define carpal ligament injuries and to plan precisely the best treatment.

What are the principal features ?:

*1: New anatomical descriptions of carpal ligaments including their course and attachments (Taleisnik, 1976) were performed. Studies of their biomechanical role and pathomechanics followed. These intracapsular or intra-articular ligaments are not visible during the surgical approach of the wrist joint, which explains why they were described only recently.

*2: Assessment of partial or total injury of each ligament and the consequences of each on this complex joint is possible. These injuries improperly called “wrist sprain” are each now well-known diagnoses and each ligament injury results in a particular pathology.

*3: Wrist osteoarthritis (O.A.) is post-traumatic in 95% of the cases (Watson, 1984) and in 75% secondary to a carpal instability.

Carpal Ligament Instability: www.emedicine.com/orthoped/topic380.htm

INTRODUCTION: www.emedicine.com/orthoped/topic380.htm

The human wrist joint is a complex arrangement of small bones and ligaments that form a mobile yet stable link from the powerful forearm to the hand.

The normally functioning carpus can position the hand precisely relative to the forearm and provides remarkably stable transmission of forces.

Motion and stability of the carpus provide the critical foundation for maximum hand function from precise fine motor control to power grip activities.

When the normal mechanics of the wrist are disrupted, the instability of the carpal bones results in weakness, stiffness, chronic pain, and often arthritis if not treated appropriately.

Although the early clinical and radiographic findings may be subtle, an understanding of wrist kinematics and instability patterns can facilitate early diagnosis and management.

Unfortunately, selecting the optimal treatment remains a difficult judgment in most cases.

Linscheid et al described traumatic carpal instability in 1972.

Since the early reports, anatomic and biomechanical studies have provided a foundation for understanding carpal motion, stresses, and pathologic instability.

Building on these studies, various models have been suggested to explain the remarkable strength and mobility of this complex joint and the predictable patterns of failure.

This article presents the current understanding of pathologic carpal instability, the common classification patterns, and early treatment options that may avoid protracted dysfunction. Appropriate hand therapy is essential to maximize recovery but requires an appreciation of the limitations of carpal instability dysfunction and the goals of various treatment options.

Problem:

Carpal instability is defined as any malalignment of the carpus. This may be evident on plain radiography as a static deformity; alternatively, the situation may be a dynamic one, which becomes evident only when external forces are placed on the wrist.

The malalignment may appear after a single traumatic event or may be secondary to chronic attenuation of supporting ligaments after a traumatic event or secondary to an underlying disease process (eg, rheumatoid arthritis, pseudogout).

Frequency:

In 1975, Dobyns et al reviewed their experience and found that 10% of all carpal injuries resulted in instability.

In 1988, Jones evaluated 100 consecutive patients with wrist sprains by using dynamic radiography (clenched-fist views) and found that 19 had an increased scapholunate gap.

The incidence of carpal instability that is associated with other specific fractures is relatively high.

Reviewing 134 distal radius fractures, Tang in 1992 found radiographic evidence of carpal instability in 30% of the cases.

Geissler and Freedland prospectively reviewed 60 displaced intra-articular distal radius fractures that were being treated with arthroscopic assisted reduction and internal fixation (Geissler, 1996). They found 43% had concomitant tears in the fibrocartilage complex, while 32% also had tears in the scapholunate ligament.

Weber reviewed 36 patients with acute scaphoid waist fractures and found that 28% had a dorsal intercalated-segment instability (DISI) deformity (Weber, 1980).

Etiology:

Carpal instability results from an injury to one or more ligamentous or bony constraints in the wrist. Depending on the force, rate, and point of impact and on the position of the wrist, a fall on an outstretched wrist can result in a range of injuries. This spectrum includes wrist sprains, distal radius fractures, and fractures to the scaphoid and other carpal bones.

This type of trauma can also result in injury to one or more ligamentous structures in the wrist, causing carpal instability.

Perilunate instability is described as progressing from the scapholunate and the capitolunate to the lunotriquetral joint.

Using a cadaveric trauma model, Mayfield et al observed progressive injury patterns when the wrist was loaded in extension, ulnar deviation, and carpal supination (Mayfield, 1980).

This perilunar instability is divided in 4 stages (see Image 5). Stage I refers to injury to the scapholunate interosseous ligament (SLIL).

Further trauma results in dorsal subluxation of the capitate relative to the lunate, or stage II.

As the load increases, the lunotriquetral interosseous ligament (LTIL) is injured, causing a perilunate dislocation in stage III. Finally, stage IV is characterized by dislocation of the lunate from the radiolunate fossa.

However, if the carpus is pronated and the hypothenar area is struck first, an ulnar traumatic pattern may be observed.

Specifically, disruption of the ulnotriquetral ligament complex and the LTIL occurs (Stanley, 1994).

As the triquetrum no longer holds the lunate, it falls into a flexed position because of pressure from the capitate and its connection with the scaphoid.

With attenuation or injury to the dorsal intercarpal ligament, a volar intercalated-segment instability (VISI) pattern ensues; this can be visualized on lateral radiography.

An LTIL tear most commonly results in a VISI deformity.

In addition to a direct loading type of trauma, rotational force to the wrist can also result in ligamentous injuries, eg, the forces that occur when holding a power drill while the drill bit is jammed.

This type of trauma can result in injuries to the LTIL and ulnar-triquetral ligament complex and result in the lunotriquetral instability (Ruby, 1996).

Some instability patterns arise after chronic attrition of supporting ligaments.

One traumatic event may result in some subtle ligamentous injury but no clear instability initially.

However, over time, continued normal daily loading of the wrist can result in symptomatic instability.

An example is seen with scaphoid fractures, where a DISI deformity tends to appear late after the initial traumatic event.

Supporting ligaments can also be important in preventing carpal instability in the presence of other significant ligamentous injury.

For example, many cadaveric studies have shown that isolated sectioning of the SLIL does not result in frank radiographic scapholunate gap or dissociation.

In 1986, Johnson and Carrera described a midcarpal instability in which the capitate dorsally subluxes out of the cup of the lunate during a fluoroscopic dorsal-displacement stress test.

This is associated with a painful snap or click that reproduces the patient's symptoms.

They attributed the cause of this instability to attenuation of the radioscaphocapitate ligament after prior trauma.

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.