How effective are added constraints in improving TKR kinematics?

Newer designs of total knee arthroplasty (TKA), through the use of added degrees of constraint, attempt to provide a "guided motion" to restore more normal and predictable kinematics. Two such design philosophies are the posterior stabilised (PS) using a cam-post and the medial pivot (MP) concepts. Knee kinematics of 12 patients with a PS TKA, 13 subjects with a MP TKA and 10 normal subjects were compared. For kinematic assessment, patients underwent fluoroscopic assessment of the knee during a step-up exercise and deep knee bend. Fluoroscopic images were corrected for distortion and assessed using 3D model fitting to determine relative 3D motion, and a 2D method to measure the patellar tendon angle (PTA) as function of knee flexion. For the PS design the cam-post mechanism engaged between 70 degrees and 100 degrees flexion. Between extension and 50 degrees there was forward motion of the contact points. Beyond 60 degrees both condyles rolled moved posteriorly. The majority of the external rotation of the femur occurred between 50 degrees and 80 degrees . The PTA was lower than normal in extension and higher than normal in flexion. The MP exhibited no anterior movement throughout the rage of motion. The medial condyle moved minimally. The lateral contact point moved posteriorly from extension to flexion. The femur rotated externally throughout the range of flexion analysed. The PTA was similar to normal from extension to mid flexion and then higher than normal beyond to high flexion. The PS design fails to fully restrain paradoxical anterior movement and although the cam engages, it does not contribute significantly to overall rollback. The MP knee does not show significant anterior movement, the medial pivot concept appears to achieve near normal kinematics from extension to 50 degrees of knee flexion. However, the results show that at high flexion this design does not achieve normal knee kinematics.

Anti-spasticity agents for multiple sclerosis.

BACKGROUND: Spasticity is a common problem in MS patients causing pain, spasms, loss of function and difficulties in nursing care. A variety of oral and parenteral medications are available. OBJECTIVES: To assess the absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis (MS) patients. SEARCH STRATEGY: We searched the Cochrane MS Group trials register (June 2003), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2003), MEDLINE (January 1966 to June 2003), EMBASE (January 1988 to June 2003), bibliographies of relevant articles, personal communication, manual searches of relevant journals and information from drug companies. SELECTION CRITERIA: Double-blind, randomised controlled trials (either placebo-controlled or comparative studies) of at least seven days duration. DATA COLLECTION AND ANALYSIS: Two independent reviewers extracted data and the findings of the trials were summarised. Missing data were collected by correspondence with principal investigators. A meta-analysis was not performed due to the inadequacy of outcome measures and methodological problems with the studies reviewed. MAIN RESULTS: Twenty-six placebo-controlled studies (using baclofen, dantrolene, tizanidine, botulinum toxin, vigabatrin, prazepam, threonine and cannabinoids) and thirteen comparative studies met the selection criteria and were included in this review. Only fifteen of these studies used the Ashworth scale, of which only three of the eight placebo-controlled trials and none of the seven comparative studies showed a statistically significant difference between test drugs. Spasms, other symptoms and overall impressions were only assessed using unvalidated scores and results of functional assessments were inconclusive. REVIEWER'S CONCLUSIONS: The absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis is poorly documented and no recommendations can be made to guide prescribing. The rationale for treating features of the upper motor neurone syndrome must be better understood and sensitive, validated spasticity measures need to be developed.

Anti-spasticity agents for multiple sclerosis.

BACKGROUND: Spasticity is a common problem in MS patients causing pain, spasms, loss of function and difficulties in nursing care. A variety of oral and parenteral medications are available. OBJECTIVES: To assess the absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis (MS) patients. SEARCH STRATEGY: Randomised controlled trials (RCTs) of anti-spasticity agents were identified using MEDLINE, EMBASE, bibliographies of relevant articles, personal communication, manual searches of relevant journals and information from drug companies. SELECTION CRITERIA: Double-blind, randomised controlled trials (either placebo-controlled or comparative studies) of at least seven days duration. DATA COLLECTION AND ANALYSIS: Two independent reviewers extracted data and the findings of the trials were summarised. Missing data were collected by correspondence with principal investigators. A meta-analysis was not performed due to the inadequacy of outcome measures and methodological problems with the studies reviewed. MAIN RESULTS: Twenty-three placebo-controlled studies (using baclofen, dantrolene, tizanidine, botulinum toxin, vigabatrin, prazepam and threonine) and thirteen comparative studies met the selection criteria. Only thirteen of these studies used the Ashworth scale, of which only three of the six placebo-controlled trials and none of the seven comparative studies showed a statistically significant difference between test drugs. Spasms, other symptoms and overall impressions were only assessed using unvalidated scores and results of functional assessments were inconclusive. REVIEWER'S CONCLUSIONS: The absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis is poorly documented and no recommendations can be made to guide prescribing. The rationale for treating features of the upper motor neurone syndrome must be better understood and sensitive, validated spasticity measures need to be developed.

Anti-spasticity agents for multiple sclerosis.

BACKGROUND: Spasticity is a common problem in MS patients causing pain, spasms, loss of function and difficulties in nursing care. A variety of oral and parenteral medications are available. OBJECTIVES: To assess the absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis (MS) patients. SEARCH STRATEGY: Randomised controlled trials (RCTs) of anti-spasticity agents were identified using MEDLINE, EMBASE, bibliographies of relevant articles, personal communication, manual searches of relevant journals and information from drug companies. SELECTION CRITERIA: Double-blind, randomised controlled trials (either placebo-controlled or comparative studies) of at least seven days duration. DATA COLLECTION AND ANALYSIS: Two independent reviewers extracted data and the findings of the trials were summarised. Missing data were collected by correspondence with principal investigators. A meta-analysis was not performed due to the inadequacy of outcome measures and methodological problems with the studies reviewed. MAIN RESULTS: Twenty-three placebo-controlled studies (using baclofen, dantrolene, tizanidine, botulinum toxin, vigabatrin, prazepam and threonine) and thirteen comparative studies met the selection criteria. Only thirteen of these studies used the Ashworth scale, of which only three of the six placebo-controlled trials and none of the seven comparative studies showed a statistically significant difference between test drugs. Spasms, other symptoms and overall impressions were only assessed using unvalidated scores and results of functional assessments were inconclusive. REVIEWER'S CONCLUSIONS: The absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis is poorly documented and no recommendations can be made to guide prescribing. The rationale for treating features of the upper motor neurone syndrome must be better understood and sensitive, validated spasticity measures need to be developed.

The use of semipermeable dressings in fingertip injuries.

A randomised prospective trial was carried out to compare the use of semipermeable and petroleum gauze dressings in fingertip injuries. The results demonstrate advantages in the use of semipermeable dressings.

A simple adjustable functional brace for tibial fractures.

The use of an adjustable functional brace for fractures of the tibia has several practical and theoretical advantages. The high cost of commercially available braces has limited their use until now. We describe a simple, inexpensive orthosis which has given good results in a clinical study for 32 unselected fractures. The fractures' alignment was well maintained. The brace was comfortable to wear and there were few complications. It is hoped that the low cost of this simple custom-made brace will encourage more widespread use of this technique.

MacIntosh arthroplasty for the rheumatoid knee: a 10-year follow up.

The results of 75 MacIntosh arthroplasties performed for rheumatoid arthritis of the knee in 63 patients were reviewed at least 10 years after surgery. Forty-two knees in 35 patients were available for assessment. Eleven arthroplasties had been revised to total knee replacement without difficulty because of pain or poor function. The remaining 31 knees in 25 patients gave good or excellent results in 22 cases, fair in eight, and poor in one. Seven patients could not be traced, and 21 patients representing 26 knees had died. At least half these knees had given satisfactory results immediately before death judged by review of the case notes. The difficulty of comparing functional status with the preoperative state because of progressive multiarticular disease was highlighted. Although greater angular deformities preoperatively reduced the chance of success in the medium term, late failure of the arthroplasty after five years was very rare. Approximately two-thirds of all the arthroplasties performed gave satisfactory results at 10-year follow up or until the time of death.

Reflex inhibition of the quadriceps after meniscectomy: lack of association with pain.

We have examined the severity and duration of reflex inhibition of quadriceps activation after arthrotomy and meniscectomy, its relationship with pain, and the effect of local anaesthesia on this relationship. Fourteen men, on completion of medial meniscectomy by arthrotomy, received either 10 ml (B10 group) or 15 ml (B15 group) of 0.5% bupivacaine hydrochloride ('Marcaine Plain') into the knee, or no injection (control group). Reflex inhibition of quadriceps was measured as the percentage reduction, from the ipsilateral preoperative value, in the integrated surface electromyogram recorded during maximal voluntary isometric contractions with the knee in extension. Pain during each contraction was recorded on a linear analogue scale. Unoperated limbs showed no evidence of quadriceps inhibition. In the operated limbs, at 1-2 h post-operatively, controls had both severe inhibition (median = 62%) and severe pain on attempting a maximal quadriceps contraction. The B10 group had similar inhibition but less pain (P less than or equal to 0.005, Wilcoxon 2-sample, 1-tailed test). In the B15 group both inhibition (P less than or equal to 0.05) and pain (P less than or equal to 0.01) were less than in the controls. These effects of bupivacaine had been lost by 4-5 h post-operatively. At 3-4 days, inhibition was still severe (median = 75%) in all three groups of patients but pain was only mild or absent. At 10-15 days, median inhibition was still 35%, but there was little or no pain. We conclude that postmeniscectomy inhibition is not simply due to perceived pain but is due, at least in part, to stimuli from the knee.

Transmission of pressure into the human limb from pneumatic splints.

The anterior compartment of the leg of 4 volunteers was used to study the transmission of externally applied pressure into a limb. The pressure from a pneumatic splint was found to be transmitted directly into the leg and was found to be added to the resting intramuscular pressure. The median inflation pressure of such a splint applied by trained ambulance personnel was 25 mm Hg (range 15-36 mm Hg). When the resting intramuscular pressure was raised experimentally, either by voluntary muscular contraction or venous engorgement, numerical addition of externally applied pressure was again observed. A moderate rise in compartment pressure commonly occurs after injury. Due care should be taken in the use of pneumatic splints or compressive dressings as the total pressure generated within a limb may be sufficient to induce ischaemia.

The bucket-handle tear of the meniscus. A clinical and arthrographic study.

A retrospective series of 272 operatively proven bucket-handle tears of the meniscus has been studied to define the natural history of the tear and to assess the accuracy of arthrography as a diagnostic technique. A simple twist, or a sporting injury accounted for most tears in the 196 patients on whom information was sufficient to allow analysis. There was, however, either no known trauma or merely a history of crouching in 20 per cent of patients. These were distributed evenly throughout the age range. Most of the 272 patients presented either with a locked knee (43 per cent) or with a history of locking (37 per cent). Fifty per cent of those with a previous history of locking but who were clinically unlocked at the time of operation, had displaced bucket-handle tears, indicating that unlocking of the knee joint frequently represents anterior extension of the tear, rather than relocation of the displaced fragment of meniscus. Significant meniscal tears were identified in 77 per cent of the 187 arthogram reports that were studied. Most errors in diagnosis seemed to occur when the separated fragment was hidden in the intercondylar notch and the peripheral rim was misinterpreted as an intact meniscus.

The slit catheter: a comparison with the wick catheter in the measurement of compartment pressure.

The slit catheter, a new instrument for the measurement of compartment pressure, has been compared with the wick catheter in experimental conditions. The two catheters were inserted into the anterior tibial compartments of 8 human legs and controlled external pressures were applied by means of an inflatable limb bag. The mean resting intramuscular pressure of 8.5 +/- 6.2 mmHg for the slit and 8.7 mmHg +/- 6.2 mmHg for the wick catheter agrees with that of other workers, and the slit catheter records a pressure at all applied external pressures not significantly different from the wick catheter (paired t test). The slit catheter provides a simple and inexpensive way of estimating compartment pressure which is as accurate as a method widely used both experimentally and clinically in North America.

Compartmental pressure changes during calcaneal traction in tibial fractures.

The effect of calcaneal traction on the compartmental pressure in the legs of five individuals with tibial fractures was studied. Mean resting pressures without traction were found to be 31.9 mmHg for the deep posterior compartment and 27.0 mmHg for the anterior compartment. For each kilogram weight of traction applied the deep posterior pressure rose by 5.7 per cent of the resting value and the anterior pressure by 1.6 per cent. It is suggested that the weight of traction should be only sufficient to render the patient comfortable and maintain alignment of the limb. Excessive traction is likely to increase the risk of compartmental ischaemia. The application of six kilograms of traction would raise the mean resting pressure by 34 per cent from 31.9 to 42.7 mmHg.