Robin R. Richards

The relationship between wrist position, grasp size, and grip strength☆☆☆

In the first part of this study, the position assumed by a normal wrist during unconstrained maximal grip and the relationship between wrist position and grip strength were investigated in 20 healthy subjects. Grip strength and wrist position were recorded in the self-selected position and then again while the subjects voluntarily deviated the wrist randomly into flexion, extension, or radial or ulnar deviation of 10 to 15 degrees. The self-selected position was 35 degrees of extension and 7 degrees of ulnar deviation. Grip strength was significantly less in any position of deviation from this self-selected position, even after accounting for fatigue. With the wrist in only 15 degrees of extension or in neutral radio-ulnar deviation, grip strength was reduced to two thirds to three fourths of normal. Sex did not affect wrist position. The dominant wrists were within 5 degrees of the nondominant ones but were relatively less extended and in more ulnar deviation. Grip strength is significantly reduced when wrist position deviates from this self-selected optimum position. In the second part of the study, the effect of grasp size on this self-selected position was studied in 21 subjects. The degree of wrist extension was inversely and linearly related to how large a setting on the Jamar dynamometer was used. This was true regardless of hand size, although the effect was more significant for smaller hands. Radial and ulnar deviations were not affected by handle position. A minimum of 25 degrees of wrist extension was required for optimum grip strength.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of malunion on functional outcome after plate fixation of fractures of both bones of the forearm in adults.

Fifty-five adults who had a fracture of both bones of the forearm were managed with plating and were followed for a mean of six years (range, one year to sixteen years and two months) with functional and radiographic assessment. Malunion was quantified by measurement of the amount and location of the maximum radial bow in relation to the contralateral, normal forearm. Fifty-four of the radial and fifty-four of the ulnar fractures united. Eighty-four per cent of the patients had an excellent, good, or acceptable functional result, according to the criteria of Grace and Eversmann. Bone-grafting did not affect the rate of union. Restoration of the normal radial bow was related to the functional outcome. A good functional result (more than 80 per cent of normal rotation of the forearm) was associated with restoration of the normal amount and location of the radial bow (p less than 0.05 and p less than 0.005). Similarly, the recovery of grip strength was associated with restoration of the location of the radial bow toward normal (p less than 0.005).

DYNAMIC RADIO-ULNAR CONVERGENCE AFTER THE DARRACH PROCEDURE

We reviewed 23 patients who had had 25 Darrach procedures for traumatic or post-traumatic disorders of the wrist at a mean follow-up of 75.5 months (36 to 121). The mean age at the time of operation was 61.1 years (34 to 82). All patients were reviewed in person. Assessment included a history, a questionnaire on patient satisfaction and a detailed physical examination. Standardised radiographs of both wrists were taken with the patients hands in a resting position and during maximal grip. Convergence of the distal ulnar stump towards the distal radius during maximal grip (dynamic radio-ulnar convergence) was seen in 14 wrists including five with actual contact (dynamic radio-ulnar impingement), but this produced symptoms in only two cases. The presence of dynamic radio-ulnar convergence did not correlate with grip strength, pinch strength, range of movement or wrist score, but was associated with increased length of excision of the distal ulna. Nineteen of the 23 patients were satisfied with the procedure. Dynamic radio-ulnar convergence is common after the Darrach procedure, but is rarely symptomatic; resection of the distal ulna remains a reliable procedure in the older patient with pain and loss of movement. Excision of the lower end of the ulna should be restricted to the least required to restore full rotation.

Shoulder arthrodesis using a pelvic-reconstruction plate. A report of eleven cases.

Eleven adults who had a flail shoulder due to brachial plexus palsy had arthrodesis of the shoulder using a single ten-hole pelvic-reconstruction plate. Both the glenohumeral and the acromiohumeral joints were fused with the shoulder in the position of 30 degrees of abduction, 30 degrees of flexion, and 30 degrees of internal rotation. No bone graft was used. The patients were immobilized in a spica cast for six weeks postoperatively. At an average follow-up of twenty-five months after the operation, the position of the arthrodesis had been maintained and solid fusion had occurred in each shoulder. No patient required removal of the plate. The pelvic-reconstruction plate is malleable and is more easily contoured in the operating room than a dynamic-compression plate. We recommend the use of a malleable pelvic-reconstruction plate when performing arthrodesis of the shoulder.

A comparison of the effects of skin coverage and muscle flap coverage on the early strength of union at the site of osteotomy after devascularization of a segment of canine tibia.

A study was done to compare the effects of coverage with skin and those of coverage with a muscle flap on the early return of strength at the site of an osteotomy after interposition of a devascularized segmental autogenous graft, two centimeters long, from a canine tibia. The bone was fixed with a plate. Thirty-two animals were randomized into two groups, one of which was treated with skin coverage and the other of which was treated with muscle flap coverage. Half of the animals from each group were killed at eight weeks and half, at twelve weeks postoperatively. The tibiae were tested to failure in four-point bending. Failure occurred primarily through the site of the distal osteotomy. Maximum bending load (p = 0.0002) and energy absorbed to failure (p less than 0.02) increased significantly between eight and twelve weeks postoperatively in the group in which a muscle flap had been used for coverage. Bending stiffness was significantly greater at eight weeks in the group in which a muscle flap had been used for coverage than in the group in which skin had been used (p less than 0.03). Maximum bending load was also significantly increased at twelve weeks in the group in which a muscle flap had been used compared with the group in which skin had been used (p less than 0.05).

Operative treatment of palsy of the posterior interosseous nerve of the forearm.

The cases of forty patients who were operated on consecutively for palsy of the posterior interosseous nerve were analyzed. The injury was iatrogenic in sixteen patients, traumatic in fifteen, and nontraumatic in nine. Persistent paralysis (partial or complete) was the only indication for operation. Operative neurolysis was done in twenty-three patients; interfascicular nerve-grafting, in twelve; internal neurolysis, in one; and tendon transfer, in four. An excellent or good functional result was documented for all but three patients, of whom two had had neurolysis and one, nerve-grafting.

Pathophysiological Effect of Fat Embolism in a Canine Model of Pulmonary Contusion

BACKGROUNDnThe objective of this study was to determine the individual and combined effects of pulmonary contusion and fat embolism on the hemodynamics and pulmonary pathophysiology in a canine model of acute traumatic pulmonary injury.nnnMETHODSnAfter a thoracotomy, twenty-one skeletally mature dogs were randomly assigned to one of three groups. Unilateral pulmonary contusion alone was produced in Group 1 (seven dogs); pulmonary contusion and fat embolism, in Group 2 (seven dogs); and fat embolism alone, in Group 3 (seven dogs). Pulmonary contusion was produced by standardized compression of the left lung with a piezoelectric force transducer. Fat embolism was produced by femoral and tibial reaming followed by pressurization of the intramedullary canals. Cardiac output, systolic blood pressure, peak airway pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, partial pressure of arterial oxygen, and partial pressure of carbon dioxide were monitored for all groups. From these data, several outcome parameters were calculated: total thoracic compliance, alveolar-arterial oxygen gradient, and ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration. All of the dogs were killed after eight hours, and tissue samples were obtained from the brain, kidneys, and lungs for histological analysis. Lung samples were assigned scores for pulmonary edema (the presence of fluid in the alveoli) and inflammation (the presence of neutrophils or hyaline membranes, or both). The percentage of the total area occupied by fat was determined.nnnRESULTSnPulmonary contusion alone caused a significant increase in the alveolar-arterial oxygen gradient but only after seven hours (p = 0.034). Fat embolism alone caused a significant transient decrease in systolic blood pressure (p = 0.001) and a significant transient increase in pulmonary arterial pressure (p = 0.01) and pulmonary capillary wedge pressure (p = 0.015). Fat embolism alone also caused a significant sustained decrease in the ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration (p = 0.0001) and a significant increase in the alveolar-arterial oxygen gradient (p = 0.0001). The combination of pulmonary contusion and fat embolism caused a significant transient increase in pulmonary capillary wedge pressure (p = 0.0013) as well as a significant sustained decrease in partial pressure of arterial oxygen (p = 0.0001) and a significant decrease in systolic blood pressure (p = 0.001) that lasted for an hour. Pulmonary contusion followed by fat embolism caused a significant increase in peak airway pressure (p = 0.015), alveolar-arterial oxygen gradient (p = 0.0001), and pulmonary arterial pressure (p = 0.01), and these effects persisted for five hours. Total thoracic compliance was decreased 6.4 percent by pulmonary contusion alone, 4.6 percent by fat embolism alone, and 23.5 percent by pulmonary contusion followed by fat embolism. The ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration was decreased 23.7 percent by pulmonary contusion alone, 52.3 percent by fat embolism alone, and 65.8 percent by pulmonary contusion followed by fat embolism. The mean pulmonary edema score was significantly higher with the combined injury than with either injury alone (p = 0.0001). None of the samples from the lungs demonstrated inflammation. Fat embolism combined with pulmonary contusion resulted in a significantly greater mean percentage of the area occupied by fat in the noncontused right lung than in the contused left lung (p = 0.001); however, no significant difference between the right and left lungs could be detected with fat embolism alone. The mean percentage of the glomerular and cerebral areas occupied by fat was greater with fat embolism combined with pulmonary contusion than with fat embolism alone (p = 0.0001 and p = 0.01, respectively). (ABSTRACT TRUNCATED)

Current concepts review : Chronic disorders of the forearm

The forearm fulfills an important role in the integrated function of the upper extremity. It maintains a stable link between the elbow and the wrist, provides an origin for many of the muscles that insert on the hand, and allows rotation of the wrist to position the hand more effectively in space. Acute injuries can involve different components of the forearm unit simultaneously, thus necessitating integrated treatment of all of the injured structures for recovery of function14,22,48,68,71,107. Chronic disorders of the forearm interfere with the stability, strength, and rotatory motion required to allow effective function of the hand. The treatment of these disorders is complex, as they involve both bone and soft-tissue structures; moreover, the lack of a generally accepted classification system leads to confusion regarding diagnosis and treatment. The anatomical location of the forearm between the elbow and the wrist has not inspired the intense scrutiny by subspecialists that has been provoked with regard to the hand, wrist, and elbow. The purpose of the current review is to discuss chronic skeletal disorders of the forearm in adults.nnNormal function of the forearm requires intact skeletal structures; a normal interosseous membrane; stable proximal and distal radio-ulnar joints; and normal soft-tissue structures, including the muscles, nerves, and vessels that are in the forearm and that traverse it. In the distal aspect of the forearm, the radius dwarfs the ulna and accounts for 80 per cent of the force transmitted from the wrist to the forearm100. The relative amount of force transmitted to the forearm from the wrist is closely associated with the relative lengths of the radius and ulna. Normally, the two bones are of nearly equal lengths51,63. Ulnar variance results if they …

The role of methylmethacrylate monomer in the formation and haemodynamic outcome of pulmonary fat emboli

We examined the roles of methylmethacrylate (MMA) monomer and cementing technique in the formation, and haemodynamic outcome, of pulmonary fat emboli. The preparation of the femoral canal and the cementing technique were studied in four groups of adult dogs as follows: control (no preparation); lavage; cement pressurisation; and cement pressurisation after lavage. We measured the intramedullary pressure, pulmonary artery pressure (PAP), pulmonary capillary wedge pressure and bilateral femoral vein levels of triglyceride, cholesterol and MMA monomer at rest and after reaming, lavage, and cementing. Femoral vein triglyceride and cholesterol levels did not vary significantly from resting levels despite significant elevations in intramedullary pressure with reaming, lavage and cementing (p = 0.001). PAP was seen to rise significantly with reaming (p = 0.0038), lavage (p = 0.0031), cementing (p = 0.0024) and cementing after lavage (p = 0.0028) while the pulmonary capillary wedge pressure remained unchanged. MMA monomer was detected in femoral vein samples when cement pressurisation was used. Intramedullary lavage before cementing had no significant effect on the MMA level. Haemodynamic evidence of pulmonary embolism was noted with reaming and intramedullary canal preparation, irrespective of the presence of MMA monomer. We found no relationship between MMA monomer level and intramedullary pressure, PAP or pulmonary capillary wedge pressure. Our findings suggest that the presence of MMA monomer in femoral venous blood has no effect on the formation of fat emboli or their pulmonary haemodynamic outcome during cemented hip arthroplasty.

Amplified Inflammatory Response to Sequential Hemorrhage, Resuscitation, and Pulmonary Fat Embolism: An Animal Study

BACKGROUNDnThe objective of this study was to assess the role of pulmonary fat embolism caused by intramedullary pressurization of the femoral canal in the development of acute lung injury in the setting of acute hemorrhagic shock and resuscitation.nnnMETHODSnThirty New Zealand White rabbits were randomly assigned to one of four groups: (1) nine animals in which hemorrhagic shock was induced by carotid bleeding, resuscitation was performed, and the femoral canal was reamed and pressurized with bone cement to induce fat embolism (hemorrhagic shock and resuscitation/fat embolism [HR/FE] group); (2) six animals in which shock was induced by carotid bleeding, resuscitation was performed, and a sham knee incision was made and closed without drilling, reaming, or pressurization (hemorrhagic shock and resuscitation [HR] group); (3) eight animals in which no hemorrhage or shock was induced but the femoral canal was reamed and pressurized with bone cement to induce fat embolism (fat embolism [FE] group); and (4) seven animals that had a three-hour ventilation period followed by a sham knee incision (control group). The animals were ventilated for four hours following closure. Flow cytometry with use of antibodies against CD45 and CD11b was performed to test neutrophil activation in whole blood. Histological examination of lung specimens was also performed. Plasma and bronchoalveolar lavage fluid were analyzed for monocyte chemotactic peptide-1 and interleukin-8 levels with use of the ELISA (enzyme-linked immunosorbent assay) method.nnnRESULTSnThree animals in the HR/FE group died immediately after canal pressurization and were excluded. CD11b mean channel fluorescence was significantly elevated, as compared with baseline, only in the HR/FE group at two hours (p = 0.025) and four hours (p = 0.024) after knee closure. Histological analysis showed that only the HR/FE (p < 0.001) and HR (p = 0.010) groups had significantly greater infiltration of alveoli by polymorphonuclear leukocytes as compared with that in the controls. No significant differences in plasma cytokine levels were found between the groups. Only the HR/FE group had significantly higher interleukin-8 (p = 0.020) and monocyte chemotactic peptide-1 (p = 0.004) levels in the bronchoalveolar lavage fluid as compared with those in the controls.nnnCONCLUSIONSnFat embolism from canal pressurization alone did not activate a pulmonary inflammatory response. The combination of hemorrhagic shock, resuscitation, and fat embolism elicited neutrophil activation, infiltration of alveoli by polymorphonuclear leukocytes, and inflammatory cytokine expression in bronchoalveolar lavage fluid.