Biomedical subjects

C Michael Robinson

Publications and source records attributed to C Michael Robinson.

12 recordsLinked to original sources

PubMed2006

Functional outcome and risk of recurrent instability after primary traumatic anterior shoulder dislocation in young patients.

BACKGROUND: The prevalence and risk factors for recurrent instability and functional impairment following a primary glenohumeral dislocation remain poorly defined in younger patients. We performed a prospective cohort study to evaluate these outcomes. We also aimed to produce guidelines for the design of future clinical trials, assessing the efficacy of interventions designed to improve the outcome after a primary dislocation. METHODS: We performed a prospective cohort study of 252 patients ranging from fifteen to thirty-five years old who sustained an anterior glenohumeral dislocation and were treated with sling immobilization, followed by a physical therapy program. Patients received regular clinical follow-up to assess whether recurrent instability had developed. Functional assessments were made and were compared for two subgroups: those who had not had instability develop and those who had received operative stabilization to treat recurrent instability. RESULTS: On survival analysis, instability developed in 55.7% of the shoulders within the first two years after the primary dislocation and increased to 66.8% by the fifth year. The younger male patients were most at risk of instability, and 86.7% of all of the patients known to have recurrent instability had this complication develop within the first two years. A small but measurable degree of functional impairment was present at two years after the initial dislocation in most patients. Sample-size calculations revealed that a relatively small number of patients with a primary dislocation would be required in future clinical trials examining the effects of interventions designed to reduce the prevalence of recurrent instability and improve the functional outcome. CONCLUSIONS: Recurrent instability and deficits of shoulder function are common after primary nonoperative treatment of an anterior shoulder dislocation. There is substantial variation in the risk of instability, with younger males having the highest risk and females having a much lower risk. Future clinical trials to evaluate primary interventions should evaluate the prevalence of recurrent instability and functional deficits, with use of an assessment tool specifically for shoulder instability, during the first two years after the initial dislocation.

Adolescent↗

PubMed2005

Mortality after low-energy fractures in patients aged at least 45 years old.

BACKGROUND: Fractures sustained in low-energy injuries are recognized as a major public health issue, although, with the exception of proximal femoral fractures, little is known about the subsequent mortality rates. The aim of this study was to compare the survival rates of a population of individuals who sustained 3 types of low-energy fractures with age-matched cohorts from within the same population. METHODS: Between January 1988 and December 1999, data were prospectively gathered from all inpatient and outpatient fracture cases at a single trauma unit. During this time, 18,019 patients sustained low-energy fractures of the proximal femur, proximal humerus, or wrist. Survival analysis using the life table method was performed and hazard ratios calculated for risk of mortality when compared to general population controls within the first year postinjury, between the second and fifth years postinjury, and between the sixth and tenth years postinjury. The effects of various social, physical, and mental health parameters on survival were also analyzed using a Cox proportional hazards model. RESULTS: The patients who sustained proximal femoral fractures were older and significantly more physically and mentally impaired than the patients who sustained wrist fractures. The demographic features of the proximal humeral fracture cohort were intermediate between these 2 groups. The mortality was high in all age groups following proximal femoral and proximal humeral fractures, though the relative risk of death, when compared to age-matched population controls, decreased with increasing age at fracture. The risk of death in these groups was greatest in younger individuals and in the first year postinjury. The wrist fracture population had similar or enhanced survival when compared to age-matched population controls. The mortality after fracture was independently predicted by age at fracture, male gender, and use of walking aids, for all 3 fracture groups (P < 0.05), and additionally by level of social dependence in the proximal femoral fracture group (P < 0.05). LEVEL OF EVIDENCE: level one, prospective cohort study. CONCLUSIONS: There is prolonged risk of premature mortality seen in both proximal femoral and proximal humeral fracture groups in the younger age cohorts, possibly as a result of concomitant medical comorbidities contributing to their premature deaths. Elderly patients sustaining proximal femoral fractures, despite high risk of mortality in the first year after injury, have survival approaching those of the general population in the longer term. Elderly patients who sustain wrist fractures have consistently better survival rates than the general population. This group of patients may be physiologically more robust than their age-matched peers in the general population.

Accidental Falls↗

PubMed2005

Posterior shoulder dislocations and fracture-dislocations.

Posterior shoulder dislocations and fracture-dislocations are uncommon injuries that most often occur during seizures or as a result of high-energy trauma. Despite advances in imaging, they are frequently diagnosed late. Detection is facilitated by heightened clinical suspicion of the injury in high-risk individuals together with appropriate radiographic investigation. A wide variety of operative techniques, ranging from simple closed reduction to soft-tissue and bone stabilization procedures to prosthetic arthroplasty, are available to treat these injuries. Selection of the most appropriate treatment option is complex and multifactorial. Because of the rarity of these injuries, evidence-based treatment protocols are difficult to devise. Good functional outcomes are associated with early detection and treatment of isolated posterior dislocations that are associated with a small osseous defect and are stable following closed reduction. Poor prognostic factors include late diagnosis, a large anterior defect in the humeral head, deformity or arthrosis of the humeral head, an associated fracture of the proximal part of the humerus, and the need for an arthroplasty.

Humans↗

PubMed2005

Trochanteric-entry long cephalomedullary nailing of subtrochanteric fractures caused by low-energy trauma.

BACKGROUND: Subtrochanteric fractures of the femur that are caused by low-energy trauma are less common than other proximal femoral fractures, but they occur in a similar population of elderly individuals, who are often socially dependent and medically frail. Although a wide range of operative techniques have been used, cephalomedullary nailing theoretically provides the most minimally invasive and biomechanically stable means of treating these complex fractures. The purpose of the present review was to evaluate the functional outcome and perioperative complications associated with the use of a trochanteric-entry cephalomedullary nail to treat all low-energy subtrochanteric fractures that were seen at a single institution. METHODS: Over an eight-year period, we used the long Gamma nail to treat a consecutive series of 302 local patients who had sustained a subtrochanteric fracture during low-energy trauma. The mortality, prevalence of complications, and functional outcome were prospectively assessed during the first year after the injury. Survival analysis was used to assess the rates of reoperation and implant revision during the first year after surgery. RESULTS: At one year, seventy-four (24.5%) of the original 302 patients had died and seventeen (5.6%) had been lost to follow-up. The remaining 211 patients (69.9%) were evaluated with regard to the functional outcome and postoperative complications during the first year after the injury. As with other proximal femoral fractures in the elderly, there was an increased level of social dependence, an increase in the use of walking aids, and a reduction in mobility among survivors. Although eighty-eight (41.7%) of the 211 patients who were evaluated at one year after the injury had some degree of hip discomfort, only two described the pain as severe and disabling. Reoperation for the treatment of implant or fracture-related complications was required in twenty-seven (8.9%) of the 302 patients; however, only eighteen of these patients required nail revision, corresponding with a one-year nail-revision rate of 7.1% (95% confidence interval, 4.0% to 10.2%) on survival analysis. Of the 250 patients who survived for six months after the injury, five (2%) had a nonunion that was confirmed at the time of surgical exploration. Complications related to the proximal lag screw were seen in twelve of the original 302 patients, and a fracture distal to the tip of the nail occurred in five. Although superficial wound infection was relatively common, deep infection occurred in only five of the 302 patients. CONCLUSIONS: Subtrochanteric fractures caused by low-energy trauma are similar to other proximal femoral fractures, with a high mortality rate during the first year after the injury. Trochanteric-entry cephalomedullary nails are associated with an acceptable rate of perioperative complications and favorable functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV.

Adult↗

PubMed2005

Recurrent posterior shoulder instability.

Recurrent posterior shoulder instability is an uncommon, debilitating condition in young adults that is being diagnosed with increasing frequency. Although a number of predisposing factors have been identified, their relative importance remains poorly understood. Poor results have been reported following operative intervention to treat recurrent posterior instability with nonanatomic techniques. The more recent development of lesion-specific surgery has improved clinical results, particularly when that surgery has been performed arthroscopically. Operative treatment is therefore being increasingly recommended at an earlier stage to patients who do not respond to supervised rehabilitation programs.

Adult↗

PubMed2004

Primary nonoperative treatment of displaced lateral fractures of the clavicle.

BACKGROUND: The optimal management of displaced fractures of the lateral end of the clavicle remains controversial. Successful results have been reported both with primary open reduction and internal fixation and with nonoperative treatment. The purpose of this study was to analyze the results of employing a policy of primary nonoperative treatment of displaced lateral fractures of the clavicle. METHODS: We treated a cohort of 127 patients who had sustained a displaced fracture of the lateral end of the clavicle. With the exception of seven patients who had immediate internal fixation, all of these patients were treated nonoperatively. At the time of follow-up, nineteen patients had died or could not be traced and fifteen were interviewed by telephone only. The remaining eighty-six patients were assessed clinically at an average of 6.2 years after the injury. All of these patients had a functional evaluation and were assessed radiographically. RESULTS: Fourteen (14%) of the 101 patients who could be contacted had had symptoms severe enough to warrant delayed surgical intervention (Group I). The remaining eighty-seven patients had not undergone any surgery, and twenty-one of them (21% of the whole cohort) had a nonunion of the clavicular fracture. The average Constant score in the nonoperatively treated group was 93 points (range, 82 to 98 points). With the numbers available, there was no significant difference in the Constant or Short Form-36 (SF-36) scores between the patients with nonunion (Group II) and those in whom the fracture had healed (Group III) or between the patients who had been treated nonoperatively (Groups II and III) and those who had had delayed surgery (Group I). There was no significant difference between the SF-36 scores in any of the groups and the scores for age-matched controls in the general population. CONCLUSIONS: Nonoperative treatment of most displaced lateral fractures of the clavicle in middle-aged and elderly patients achieves a good medium-term functional result. Symptoms that were severe enough to warrant a delayed reconstructive procedure developed in only 14% of the patients. Asymptomatic nonunion does not appear to adversely affect the functional outcome in the medium term.

Adolescent↗

PubMed2004

Estimating the risk of nonunion following nonoperative treatment of a clavicular fracture.

BACKGROUND: Nonunion is a rare complication of a fracture of the clavicle, but its occurrence can compromise shoulder function. The aim of this study was to evaluate the prevalence of and risk factors for nonunion in a cohort of patients who were treated nonoperatively after a clavicular fracture. METHODS: Over a fifty-one-month period, we performed a prospective, observational cohort study of a consecutive series of 868 patients (638 men and 230 women with a median age of 29.5 years; interquartile range, 19.25 to 46.75 years) with a radiographically confirmed fracture of the clavicle, which was treated nonoperatively. Eight patients were excluded from the study, as they received immediate surgery. Patients were evaluated clinically and radiographically at six, twelve, and twenty-four weeks after the injury. There were 581 fractures in the diaphysis, 263 fractures in the lateral fifth of the clavicle, and twenty-four fractures in the medial fifth. RESULTS: On survivorship analysis, the overall prevalence of nonunion at twenty-four weeks after the fracture was 6.2%, with 8.3% of the medial end fractures, 4.5% of the diaphyseal fractures, and 11.5% of the lateral end fractures remaining ununited. Following a diaphyseal fracture, the risk of nonunion was significantly increased by advancing age, female gender, displacement of the fracture, and the presence of comminution (p < 0.05 for all). On multivariate analysis, all of these factors remained independently predictive of nonunion, and, in the final model, the risk of nonunion was increased by lack of cortical apposition (relative risk = 0.43; 95% confidence interval = 0.34 to 0.54), female gender (relative risk = 0.70; 95% confidence interval = 0.55 to 0.89), the presence of comminution (relative risk = 0.69; 95% confidence interval = 0.52 to 0.91), and advancing age (relative risk = 0.99; 95% confidence interval = 0.99 to 1.00). Following a lateral end fracture, the risk of nonunion was significantly increased only by advancing age and displacement of the fracture (p < 0.05 for both). On multivariate analysis, both of these factors remained independently predictive of nonunion (p < 0.05), and, in the final model, the risk of nonunion was increased by a lack of cortical apposition (relative risk = 0.38; 95% confidence interval = 0.25 to 0.57) and advancing age (relative risk = 0.98; 95% confidence interval = 0.97 to 0.99). CONCLUSIONS: Nonunion at twenty-four weeks after a clavicular fracture is an uncommon occurrence, although the prevalence is higher than previously reported. There are subgroups of individuals who appear to be predisposed to the development of this complication, either from intrinsic factors, such as age or gender, or from the type of injury sustained. The predictive models that we developed may be used clinically to counsel patients about the risk for the development of this complication immediately after the injury.

Adult↗

PubMed2004

Severely impacted valgus proximal humeral fractures.

BACKGROUND: The functional results associated with nonoperative treatment of severely impacted valgus fractures of the proximal part of the humerus are poor, and these injuries are difficult to treat with minimally invasive percutaneous fixation techniques. The aim of this study was to review the functional and radiographic results and complications of a new operative technique in a series of twenty-five patients. METHODS: Over a two-year period, we treated twenty-nine patients with a severely impacted valgus fracture of the proximal part of the humerus. Three patients were lost to follow-up and one died, leaving twenty-five patients who were available for the study. In all of the fractures, the head-shaft angle had been tilted into > or = 160 degrees of valgus and the greater tuberosity was displaced by >1 cm. All patients were treated with open reduction of the fracture, and the space created behind the humeral head was filled with Norian Skeletal Repair System (SRS) bone substitute. The fractures were stabilized with either screws or buttress plate fixation. Associated rotator cuff tears were repaired. All patients underwent functional outcome assessment with use of the Constant, DASH (Disabilities of the Arm, Shoulder and Hand), and SF-36 (Short Form-36) scores at one year, and twelve patients were followed for two years. RESULTS: All fractures united within the first year, all reductions were maintained, and no patient had signs of osteonecrosis of the humeral head on the latest follow-up radiographs. At one year, the median Constant score was 80 points and the median DASH score was 22 points. The functional results continued to be satisfactory in the twelve patients who were followed for two years. The results in our series were better than those achieved in studies of nonoperative treatment of similar fracture configurations. There were six clinically relevant complications, although none required a reoperation and all six patients had a satisfactory short-term functional outcome. CONCLUSIONS: Internal fixation of severely impacted valgus fractures of the proximal part of the humerus, supplemented by Norian SRS bone substitute to fill the proximal humeral metaphyseal defect, produces good early functional and radiographic outcomes. Additional follow-up will be required to assess whether these initially satisfactory outcomes are maintained over the longer term.

Contraindications↗

PubMed2004

The epidemiology of posttraumatic adult respiratory distress syndrome.

BACKGROUND: Although adult respiratory distress syndrome is an important early complication of blunt trauma, the epidemiology and risk factors for its development remain poorly defined. The aims of this study were to determine the prevalence and demographics of this complication in a prospective cohort series of patients admitted to the hospital following injury. We also assessed the contribution of the severity and pattern of the injury to the risk of this complication developing. By identifying factors associated with the highest risk of the development of adult respiratory distress syndrome, we aimed to produce guidelines to facilitate earlier detection. METHODS: We prospectively studied 7192 patients admitted to a single university hospital, over an eight-year period, for treatment of a traumatic injury. With the exception of patients who had sustained a hip fracture or who had been discharged within seventy-two hours after admission, all patients who required hospital admission following trauma, were older than thirteen years of age, and were a resident within the catchment area were included in the analysis. The prevalence and demographics of posttraumatic adult respiratory distress syndrome were identified for patients who had sustained musculoskeletal, thoracic, abdominal, and head injuries, either in isolation or in combination. The relative risks of this condition developing were calculated according to the injury pattern. Multiple logistic regression analysis was performed to identify the most highly significant predictors of the development of adult respiratory distress syndrome. RESULTS: Adult respiratory distress syndrome developed in thirty-six (0.5%) of the patients. The prevalence was significantly higher among younger patients (p = 0.002), and 83% of the cases followed high-energy trauma. The prevalence of adult respiratory distress syndrome after isolated thoracic, head, abdominal, or extremity injury was <1%. Patients with injuries to two anatomical regions had a higher prevalence (up to 2.9%), and those with injuries to three anatomical regions had an even higher prevalence (up to 10.2%). Multiple logistic regression analysis showed the Injury Severity Score, the presence of a femoral fracture, the combination of abdominal and extremity injuries, and observations of compromised physiological function on admission each to be an independent predictor of the later development of adult respiratory distress syndrome. CONCLUSIONS: The prevalence of adult respiratory distress syndrome increases with injury severity and combinations of injuries to more than one anatomical region. We have been able to quantify the importance and relative risks associated with these injuries. The implications of our findings with regard to facilitating early detection of this complication are discussed.

Adolescent↗

PubMed2003

Adult distal humeral metaphyseal fractures: epidemiology and results of treatment.

OBJECTIVES: To examine the epidemiology and results of treatment of fractures of the distal humeral metaphysis. DESIGN: Observational cohort study. SETTING: An orthopaedic trauma unit, which provides all the fracture care for a well-defined catchment population. PATIENTS/PARTICIPANTS: A consecutive series of 320 patients with distal humeral fractures admitted to the unit between January 1988 and June 1997. INTERVENTION: We adopted a protocol of open reduction and fixation of all displaced fractures (greater than 5 mm of displacement in any plane) in patients who were medically fit for anesthesia. Postoperative immobilization was a cylinder cast for 6 weeks. Patients with undisplaced fractures or who were medically unfit were also treated nonoperatively in cylinder casts for 6 weeks. MAIN OUTCOME MEASUREMENTS: Epidemiological examination of patient subgroups and the incidence of complications of treatment. RESULTS: The overall incidence of distal humeral fractures in adults during this time was 5.7 cases per 100,000 in the population per year with an almost equal male to female ratio. There was a bimodal age distribution, simple falls were the most common overall cause of fracture, and the majority of the fractures were extra-articular (AO/OTA type A) or complete articular fractures (AO/OTA type C). The risk of complications during treatment was generally low in most patients, and the majority healed their fractures uneventfully. Overall, 90.6% of fractures united within 12 weeks and just under half of the remaining 9.4% patients with union complications healed without requiring further operative intervention by 24 weeks. The risk of union complications was higher following high-energy injuries, open fractures, and nonoperative treatment. Although the AO/OTA classification was not predictive of union complications, the "low" transcondylar (type A2.3 and A3) and simple intercondylar fracture (type C1.3) configuration had a greater risk of union complications than the "high" subtype. The rate of infection, myositis ossificans, and other implant-related complications were higher following operative treatment of type C fractures than type A and B fractures. CONCLUSIONS: The epidemiology of a consecutive unselected series of adult distal humeral fractures is defined in this study. The majority of these fractures are best treated surgically by rigid open reduction and internal fixation, except for "low" Type A and C fractures, which have a higher risk of union complications. The role of total elbow arthroplasty to treat these more complex injuries requires further evaluation.

Adolescent↗

PubMed2003

Primary hemiarthroplasty for treatment of proximal humeral fractures.

BACKGROUND: Primary hemiarthroplasty of the shoulder is used to treat complex proximal humeral fractures, although the reported functional results following this method of treatment have varied widely. The aim of this study was to prospectively assess the prosthetic survival and functional outcomes in a large series of patients treated with shoulder hemiarthroplasty for a proximal humeral fracture. By determining the factors that affected the outcome, we also aimed to produce models that could be used clinically to estimate the functional outcome at one year following surgery. METHODS: A thirteen-year observational cohort study of 163 consecutive patients treated with hemiarthroplasty for a proximal humeral fracture was performed. Twenty-five patients died or were lost to follow-up in the first year after treatment, leaving 138 patients who had assessment of shoulder function with use of the modified Constant score at one year postinjury. RESULTS: The overall rate of prosthetic survival was 96.9% at one year, 95.3% at five years, and 93.9% at ten years. The overall median modified Constant score was 64 points at one year, with a typically good score for pain relief (median, 15 points) and poorer scores, with a greater scatter of values, for function (median, 12 points), range of motion (median, 24 points), and muscle power (median, 14 points). Of the factors that were assessed immediately after the injury, only patient age, the presence of a neurological deficit, tobacco usage, and alcohol consumption were significantly predictive of the one-year Constant score (p < 0.05). Of the factors that were assessed at six weeks postinjury, those that predicted the one-year Constant score included the age of the patient, the presence of a persistent neurological deficit, the need for an early reoperation, the degree of displacement of the prosthetic head from the central axis of the glenoid seen radiographically, and the degree of displacement of the tuberosities seen radiographically. CONCLUSIONS: Primary shoulder hemiarthroplasty performed for the treatment of a proximal humeral fracture in medically fit and cooperative adults is associated with satisfactory prosthetic survival at an average of 6.3 years. Although the shoulder is usually free of pain following this procedure, the overall functional result, in terms of range of motion, function, and power, at one year varies. A good functional outcome can be anticipated for a younger individual who has no preoperative neurological deficit, no postoperative complications, and a satisfactory radiographic appearance of the shoulder at six weeks. The results are poorer in the larger group of elderly patients who undergo this procedure, especially if they have a neurological deficit, a postoperative complication requiring a reoperation, or an eccentrically located prosthesis with retracted tuberosities.

Accidental Falls↗

PubMed2003

Severely impacted valgus proximal humeral fractures. Results of operative treatment.

Adult↗