Distinct patterns of fracture propagation in distal radial fractures and the relationship to the ulnar head.

BACKGROUND: The aim was to assess the direction of distal radius fractures and their relationship to the ulnar head. METHODS: We reviewed the 160 wrist radiographs. The fracture line was measured on the postero-anterior and lateral radiographs relative to the long axis of the forearm and the relationship to the ulnar head. FINDINGS: PA radiographs: the fracture line ran distal ulnar to proximal radial (ulnar to radial) in 11%, transverse in 74% and distal radial to proximal ulnar (radial to ulnar) in 16%. Lateral radiographs: the fracture line ran distal volar to proximal dorsal in 88%, transverse in two 1% and dorsal to volar in 11%. Radial shift (7.5%) only occurred with ulnar to radial or transverse fractures. The ulnar to radial fracture line started at the proximal end of the ulnar head/distal radio-ulnar joint in 88%. The radial to ulnar fracture line started ended a mean of 2.5 mm proximal to the distal radio-ulnar joint (p < 0.01). The transverse fracture line started at the base of the distal radio-ulnar joint in 53% and proximally in 47%. INTERPRETATION: There are two distinct coronal patterns: radial to ulnar ending c. 2 mm proximal to the distal radio-ulnar joint; ulnar to radial starting at the proximal distal radio-ulnar joint. There may be third pattern - transverse fractures; these may be variants of the above. Sagittally the main direction is volar to dorsal but 11% are obverse. This is the first description of distinct fracture patterns in extra-articular distal radius fractures. In addition the fracture patterns appear to correlate with different directions of force transmission which fit with our understanding of falling and the relatively uncontrolled impact of the wrist/hand with the ground. These patterns of fracture propagation help understand how the biomechanics of wrist fractures and may enable prediction of collapse.

Distal radio-ulnar implant arthroplasty: a systematic review.

The use of implant arthroplasty in the hand and wrist is increasing, often with little evidence of outcomes in the literature. We therefore undertook a systematic review of the outcomes of distal radio-ulnar joint arthroplasties following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Papers were assessed for outcomes, implant survival and methodological quality. Fourteen papers assessed ulna head replacements. The implant survival rate was 93% at a mean follow-up of 45 months. One paper assessed a partial ulna head replacement. Fourteen papers assessed total distal radio-ulnar joint replacements; all but two used the Aptis prosthesis. These implants had a survival rate of 97% at a mean of 56 months. Complications rates were 28% in both groups, and many were major. Although these data are impressive, worldwide there are many more implants placed and not followed up. All studies were level IV and V studies with low Coleman scores. This systematic review demonstrates that implant arthroplasty for the distal radio-ulnar joint has produced acceptable results in small numbers of patients. Whilst these short term outcomes are encouraging, the indications should be carefully considered and there should be proper consideration of the potential for later failure. LEVEL OF EVIDENCE: III.

Bony mallet finger injuries: assessment of stability with extension stress testing.

UNLABELLED: Bony mallet injuries with a large dorsal fracture fragment may sublux giving a poor outcome. The hypothesis that was tested was that subluxation could be predicted by extension stress lateral radiographs. It was anticipated that the main distal fracture fragment would glide and be stable or pivot and be unstable. There were 32 bony mallet injuries with dorsal fracture fragments of >1/3 in 31 patients. There were three patterns shown on lateral extension stress radiographs: gliding, pivoting, and tilting - a combination of the former two. Defining stability as congruence or subluxation ⩽1 mm at final radiographs and instability as subluxation >1 mm, there was a very strong association with pivoting and subluxation, and gliding and congruence (p < 0.001). Tilting gave mixed results. There was significant difference in the size of the fracture fragment in stable (mean 49%) and unstable injuries (54%) (p = 0.044). Extension stress testing has a sensitivity of 89% and a specificity of 100%. Extension stress testing highlights that instability is not just a function of fracture fragment size and is a more reliable method of predicting subluxation than any previously described. LEVEL OF EVIDENCE: V.

In-vivo three-dimensional measurement of distal radioulnar joint translation in normal and clinically unstable populations.

UNLABELLED: Assessment of distal radioulnar joint instability is clinically difficult and subjective. The distal radioulnar joint is postulated to 'tighten' in ulnar/radial deviation and pronation/supination. Using a rig, we measured mean distal radioulnar joint translation in neutral forearm rotation and neutral wrist radial and ulnar deviation, as well as extremes of wrist radial and ulnar deviation and forearm rotation. We tested the rig on ten cadaver forearms to validate the measurements we made. We tested 50 normal adults and 50 patients with clinical distal radioulnar joint instability. Distal radioulnar joint stability in men and women and on contralateral sides were comparable. Distal radioulnar joint translation decreased significantly with wrist radial and ulnar deviation and forearm pronation and supination, matching clinical practice and further validating the rig. The data in normal patients is comparable with previous computed tomography-based studies. Translation in all positions was statistically increased within the clinical instability group and did not cross-over with the normal ranges. Distal radioulnar joint translation is a physically measurable phenomenon. Our device appears to be a valid test of distal radioulnar joint translation, establishing normal data in vivo. LEVEL OF EVIDENCE: III.

A biomechanical study of the effects of simulated ulnar deviation on silicone finger joint implant failure.

Silicone finger arthroplasties are used widely, especially for metacarpophalangeal joint replacement in patients with inflammatory arthritis. Implant failure is well recognized. The rates of failure in vivo differ substantially from experience in vivo. One cause of failure is felt to be post-operative ulnar deviation. The aim of our study was to test the effect of ulnar deviation testing on silicone finger implants. We tested 12 implants in three groups of four implants. The implants were submerged in a bath of Ringer's solution at 370 °C throughout the experiment and tested in a rig held in 0°, 10° and 20° deviation. The rig was cycled at 1.5 Hz from 0°-90°. The implants were inspected every 500,000 cycles until a total of 4 million cycles. There was consistently increased wear and supination plastic deformity in going from 0°-20° deviation. This study confirms the adverse effects of ulnar deviation on silicone finger implant wear. It is likely that this combines with lateral pinch forces and sharp bone edges to cause catastrophic silicone implant failure. LEVEL OF EVIDENCE: III.

The non-operative management of hand fractures.

Most hand fractures can be treated non-operatively. Some hand fractures, such as open injuries or markedly displaced intra-articular fractures, are almost always treated operatively. The treatment of many fractures, such as proximal interphalangeal joint fracture subluxations or spiral phalangeal fractures, is unclear. The aim of this review is to establish those injuries where the outcome of non-operative treatment is unlikely to be improved with surgery. This may help to prevent unnecessary surgery, concentrate work on finding the sub-groups that may benefit from surgery and to establish which injuries do so well with non-operative treatment that the only valuable clinical research in future will be large cohort studies of non-operative treatment or randomized controlled trials comparing operative and non-operative treatments. The relevant fractures are spiral metacarpal fractures, transverse metacarpal shaft and neck (boxer's) fractures, base of proximal phalanx avulsion fractures, thumb metacarpophalangeal joint ulnar and radial collateral ligament injuries and bony mallet injuries. For the majority of these injuries, current knowledge suggests that the outcome of non-operative treatment cannot reliably be improved upon with surgery.

Staples for intra-operative skin retraction in hand surgery.

In certain situations staples are a quick and effective method of retracting the skin to give access to the operative site. Staples, once placed, are more reliable and predictable than an assistant with a skin hook. Furthermore, their use frees up the assistant to perform other tasks including further deeper tissue retraction. Staples pinch the skin rather than piercing it and this is especially of value in patients on steroid treatment or with thin skin that may bruise easily. They leave no discernible marks on removal.

Biomechanical study of the efficacy of a new design of wrist guard.

BACKGROUND: Upper extremity injuries are frequent in the elderly or those undertaking extreme sporting activities. Commercially available wrist guards reduce the frequency of wrist fractures but are not widely used as they greatly restrict movement. METHODS: A new wrist guard was developed which provided protection to the "impact area" but does not restrict wrist or digital movement. A human hand model and a biomechanical test rig, which allowed the simulation of an adult fall from height, were developed. The ability of the new guard, which was tested with different levels of padding, to reduce peak impact forces and absorb energy on impact was measured and compared to a commercially available wrist guard. FINDINGS: The use of any guard reduced peak impact forces by a minimum of 31.8%. The new guard, despite a substantially reduced impact surface area, demonstrated the same reductions in peak force (48%) and ability to absorb energy on impact as the standard guard when fitted with comparable levels of padding. INTERPRETATION: These results indicate that the new guard, which allows movement of the wrist and digits, demonstrates the same ability to reduce impact forces and absorb energy as a commercially available guard despite its substantially reduced impact area. Such a guard may provide a better compromise between joint flexibility and protection than the status quo.

In-vivo measurement of distal radio-ulnar joint translation.

Distal radio-ulnar joint (DRUJ) instability is increasingly recognised and assessment can be subjective and difficult. Previous research has used cadaveric models or in-vivo with CT, with variable results. A test device was designed to establish normal values of in-vivo DRUJ dorso-palmar translation. Twenty volunteers were recruited. Those with previous wrist/forearm injuries were excluded. The device held the elbow at 90° flexion and neutral forearm rotation, with the distal ulna secured. A dorso-palmar shear force was applied to the distal radius and displacement measured three times on each wrist alternately by the same operator. The mean translation of the DRUJ is 5.5 mm. Same-sided mean measurements for two subjects taken days apart varied by 1 mm. The intra-class correlation coefficient was 0.93. The device is reliable, reproducible and appears to be a simple valid test. Contralateral sides were comparable. It will primarily be a research device to guide clinical practice in DRUJ instability.

An in vitro biomechanical study comparing the spiral linking technique against the pulvertaft weave for tendon repair.

A new spiral linking technique for tendon repair in which one end of the tendon is spiralled around the other end has been developed. Using pig trotter extensor tendons, the Pulvertaft weave technique was compared with this new technique. Twenty-five repairs using each technique were tested by tensile loading with an Instron testing machine. The spiral linking technique matched the strength of Pulvertaft method: the mean peak loads were 102 and 105 N, respectively. The Pulvertaft weave was stiffer than the spiral linking technique: mean stiffness of 11.1 and 6.7 N/mm, respectively. The spiral linking technique also absorbed considerably more energy: energy absorbed prior to failure to 90% of peak load, 1.75 and 1.13 kN mm, respectively. In conclusion, the spiral linking technique appears as strong as the Pulvertaft weave and we believe it is easier to perform.

Outcome following conservative treatment of metacarpophalangeal collateral ligament avulsion fractures of the finger.

Avulsion fractures of the metacarpophalangeal joints are uncommon and there are few reports on their outcome after conservative treatment. We treated seven such patients with fracture fragment sizes between 10% and 25% of the width of the articular surface on the radiograph by early active mobilisation in neighbour strapping. The outcome of treatment was assessed at a mean follow-up of 57 (range 8-94) months. The mean visual analogue pain score was 0.6 (range 0-2) and the mean visual analogue function score was 9 out of 10 (range 6-10). The mean DASH score was 3.1 (range 0-12.5). All but one patient had normal grip strength and a full range of finger movement. We believe that the majority of avulsion fractures of the metacarpophalangeal joint can be managed successfully without surgery.

Development of an in-vivo method of wrist joint motion analysis.

BACKGROUND: A clinically applicable method of plotting wrist joint motion in three-dimensions has not been described. Computer modelling has been used to improve joint arthroplasty elsewhere in the body. We aimed to develop a method of measuring, and modelling, wrist joint motion that could potentially be used to improve the kinematic performance of wrist arthroplasty designs. METHODS: An electromagnetic system was used to record wrist motion in three-dimensions. A small pilot study attempted to assess repeatability. A larger group of volunteers with normal wrists was also studied. An iterative computer model, using a two-axis hinge, was developed. One output from this model, the offset of the two axes of motion, is presented as an example of the possible applications of this method of analysis. FINDINGS: For any one individual, in the pilot study, the offset of the axes calculated was relatively reproducible. Between individuals the difference in the offset of the axes was more marked. In 99 normal sets of data the mean axis offset was 6.8mm (range 28 mm to -21 mm) A positive value represented the radio-ulnar deviation axis placed distal to the flexion-extension axis. INTERPRETATION: The three-dimensional motion plots generated using this method could be used clinically to follow disease progression or recovery following surgery. The computer modelling method described has potential applications, if further refined, to wrist joint arthroplasty design.

A kinematic model of the wrist based on maximization of joint contact area.

The wrist is a complex joint and the factors governing its behaviour are poorly understood. A hypothesis that the movement of the carpal bones could be predicted using a minimum energy principle was tested. Carpal bones were dissected from a cadaveric forearm and their shapes were laser-digitized to obtain three-dimensional computer models. A computer program was created to measure contact area between neighbouring articular surfaces and to maximize this quantity by adjusting the six degrees of freedom of the bone models. This procedure was performed for 1.0 degree increments of rotation applied to the capitate bone up to 20 degrees of ulnar and 10 degrees of radial deviation. The model correctly predicted certain aspects of the complex behaviour of the carpal bones. The results for the scaphoid in particular displayed characteristics in common with known behaviour of this bone. During 20 degrees of unlar deviation and 10 degrees of radial deviation, the bone demonstrated 11.3 degrees of extension and 9.4 degrees of flexion respectively. The novelty of the study lay in the fact that the model did not rely upon ligamentous constraints. The results are encouraging, considering the only information used by the algorithm was the shape of the articular surfaces.

'Doctor, when can I drive?': an update on the medico-legal aspects of driving following an injury or operation.

In line with recent changes in UK legislation, we updated our position regarding the determination of fitness to drive. The responsibility for determining the fitness to drive of an individual now rests entirely with the Driving and Vehicle Licensing Agency (DVLA). Previous work on this subject was reviewed, updated published documents were evaluated and a literature search on fitness to drive following an injury or operation was carried out. We should advise our patients to drive once they feel safe, but they should be careful during the earlier stages of rehabilitation. If in any doubt, the driver should contact the DVLA and take advice accordingly from their medical advisors.

A method for measuring vertical forces applied to the upper limb during sit-to-stand.

The aim of this study was to develop a basic measurement system to estimate the vertical loading of the upper limb during the sit-to-stand activity, with a view to increasing the understanding of the loading of the wrist in daily living activities. A chair was adapted and instrumented with strain gauges and position sensors so that the force applied through the upper limbs to the arms of the chair could be calculated. Four aspects of the chair's geometry could be varied. A force plate was positioned on the floor between the legs of the chair to record the corresponding foot loading. Twenty normal subjects (22-56 years, mean 32.7 years) participated in a pilot study in which loading through the upper and lower limbs was recorded for a range of chair geometries. The vertical force transmitted through each upper limb was typically 20-30 per cent of bodyweight. The vertical upper limb load averaged across all subjects showed a small reduction when either the seat height or the height of the chair arms was increased.

Direct access carpal tunnel surgery.

Carpal tunnel syndrome is a common condition and clinical diagnosis is often easily made. A system of direct referral for day-case carpal tunnel surgery was introduced. General practitioners, physicians and surgeons were advised of the service and the criteria for referral, which included female patients with bilateral symptoms and physical signs, and some response to conservative treatment. All patients were reviewed preoperatively by the senior author (GEBG). The service was an alternative to standard outpatient referral. A total of 51 patients was seen. Two were refused surgery. In all those who underwent surgery, the symptoms either resolved or were improved. The service was well received, although some patients felt that they were poorly informed preoperatively. The mean waiting time for surgery was reduced by four months and the patients avoided an outpatient appointment. Direct access day-case carpal tunnel surgery works well by reducing delays and the costs of treatment. Adequate patient information is important to make the best of the service.

The relationship between the strength of supination of the forearm and rotation of the shoulder.

In children with obstetric brachial plexus palsy (OBPP) who develop an internal rotation deformity of the shoulder, release of subscapularis improves the range of external rotation of the shoulder and the strength of supination of the forearm. We studied the strength of supination in 35 healthy adult volunteers at 45 degrees of both internal and external rotation. The mean and maximum torques were greater in external than internal rotation by 8.7% and 7.5%, respectively. This was highly significant (p < 0.0001). The increased strength of supination in external rotation is probably because the maximum power of biceps, particularly the long head, may be exerted in this position. In children the difference may be even greater due to anatomical differences causing the dramatic increases in the strength of supination after surgery for OBPP. In adults our findings suggest that the supination exercises which are undertaken after injury or surgery to the forearm or wrist should be performed in external rotation.