Striving for statistical significance: how important is it?
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Biomedical subjects
Publications and source records attributed to J M Matta.
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OBJECTIVE: To determine the incidence of superior gluteal artery injury following fracture of the acetabulum and to determine whether the combination of a superior gluteal artery injury and the use of an extended iliofemoral approach to the acetabulum creates abductor muscle necrosis. DESIGN: Prospective protocol, consecutive cases. SETTING: A consecutive series from the referral practice of the senior author plus seven cases from the practices of two other authors. PATIENTS: Two hundred twenty-seven patients with fractures of the acetabulum were treated operatively between November 1992 and January 1995. Forty-one were treated with the use of the extended iliofemoral approach. Preoperative angiograms were not performed for any of the patients. All fractures involved the posterior column, and all but two fractures had displacement of the greater sciatic notch. The average displacement of the notch was 2.5 centimeters (range 6 to 60 millimeters). INTERVENTION: All patients were treated with open reduction and internal fixation via the extended iliofemoral approach. Intraoperative Doppler examination of the superior gluteal artery was performed before and after reduction and fixation of the posterior column. MAIN OUTCOME MEASURE: Wound complications, abductor manual muscle testing, hip range of motion. RESULTS: Pulsatile flow was confirmed in forty of forty-one patients. All patients were followed for a minimum of six months with an average follow-up of 1.4 years. At most recent follow-up, no patients had evidence of complete loss of abductor function. Sixty-three percent of patients had achieved Grade 4 of 5 motor strength, and 25 percent of them had achieved normal motor strength. CONCLUSIONS: No instances of superior gluteal artery laceration and only one instance of superior gluteal artery thrombosis were encountered in these forty-one patients despite significant fracture displacement involving the sciatic notch. The incidence of superior gluteal artery injury was significantly less than would be expected from previous studies. Massive abductor necrosis resulting from superior gluteal artery injury combined with an extended approach has been described primarily in animal and cadaver studies. Although arteriograms are useful in the control of hemodynamic instability, we cannot support the recommendation of preoperative angiographic study of all patients undergoing acetabular fracture surgery via an extended approach. In one case, an extended iliofemoral approach was tolerated in a patient with absent superior gluteal artery flow.
Two hundred twenty-five acetabular fractures treated surgically by one surgeon using a single surgical approach were reviewed to identify the incidence of clinically significant hip muscle weakness. Clinical grade of fair or poor and presence of radiographic signs of osteoarthritis were most strongly correlated with hip muscle weakness (P<.0001). Other factors related to muscle weakness were >21 days to repair, abdominal trauma, infection, avascular necrosis, heterotopic ossification resection, chest trauma, and head trauma. The presence of arthritis at follow-up increased the incidence of hip muscle weakness (46% [41/89]; P<.0001) independent of surgical approach.
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Sixty-six hips in 58 patients that had undergone periacetabular osteotomy for residual acetabular dysplasia were available for clinical and radiographic followup at a minimum of 2 years (average, 4 years) after surgery. The final clinical results were graded as 17% excellent, 59% good, 12% fair, and 12% poor. No patient who met the ideal indications for surgery had a poor result during the study period. After reviewing the results, the authors remain positive regarding the periacetabular osteotomy and recommend it for individuals with hip pain and radiographic evidence of acetabular dysplasia.
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A new technique to achieve a reliable fusion of the hip joint through an anterior approach with use of a ventral low contact dynamic compression plate and a lateral 6.5 mm lag screw is presented in detail. The advantages of this technique are that the approach does not jeopardize the vascularity of the femoral head, that the fixation on the pelvic side uses the strong bone stock of the sciatic buttress, and that the hip abductor muscles and greater trochanter are preserved. The authors also present the indications and the results of their experience with 12 patients. The followup period averaged 24.8 months (range, 10-42 months). Ten patients (83%) achieved a solid fusion by radiologic and clinical criteria. Although a moderately symptomatic nonunion developed in 1 patient, another patient went on to a painful nonunion to whom another attempt for fusion has been recommended. According to the hip score of Merle d'Aubigné and Postel, the average figures for pain and ambulation increased from 3.2 points to 5.0 points and from 2.7 points to 4.5 points, respectively, after surgery. Six of the 12 patients regained the ability to work in their former jobs or in new occupations. Eight patients felt no or minor restrictions in doing their former sports activities. Patient satisfaction was high with a majority reporting minor discomfort mainly around the fused hip.
Closed internal degloving is a significant soft-tissue injury associated with a pelvic trauma in which the subcutaneous tissue is torn away from the underlying fascia, creating a cavity filled with hematoma and liquefied fat. It commonly occurs over the greater trochanter but may also occur in the flank and lumbodorsal region. When this closed internal degloving occurs over the greater trochanter, it is known as a Morel-Lavallée lesion. We reviewed 24 patients who sustained a closed internal degloving injury. Cultures from the closed internal degloving injury were positive in 46% (11 of 24 cases). The incidence of positive cultures was not dependent on the time from injury to debridement. All wounds were treated by thorough debridement before or during pelvic or acetabular surgery. Three patients subsequently developed deep-bone infections, only one of whom had a positive culture at the initial debridement. One patient whose wound was primarily closed over suction drains developed a chronic deep soft-tissue infection requiring multiple debridements. The development of hematoma in the zone of operation reduces the safety of early operative intervention by increasing the risk of infection. An expanding hematoma in a closed internal degloving injury may further compromise the skin vascularity if not promptly drained. The injured soft tissues should be debrided early, either before or at the time of fracture fixation. The wound should be left open, and repeated surgical debridement of the injured tissue is recommended.
We have studied prospectively the effect of indomethacin on the development of heterotopic ossification (HO) after the internal fixation of acetabular fractures. After operation 107 patients randomly received either a six-week course of indomethacin or no treatment against HO. Plain radiographs of 101 patients at a mean of 7.9 months after surgery showed HO in 47.4% of the 57 patients who received indomethacin and in 56.8% of the 44 who did not. This difference was not statistically significant. Heterotopic ossification of Brooker class II or more was seen in four patients (7%) with prophylaxis and in one without (p = 0.51). Measurements of the volume of HO on 3-D CT reconstructions showed a median value of 1.5 cm3 in patients with indomethacin and 4.0 cm3 in those without (p = 0.28). When only the 57 patients in whom the operation was carried out through either a Kocher-Langenbeck or an extended iliofemoral approach were included the indomethacin group showed a median volume of 1.7 cm3 compared with 3.6 cm3. On plain radiographs Brooker class II or above was seen in 9.4% of the patients receiving indomethacin and in 4.8% of those who did not. Indomethacin was therefore not effective in preventing ectopic bone formation after surgery for acetabular fractures. There was a significant association of male gender with volume of HO using a non-parametric analysis of variance.
Unstable fractures of the pelvic ring are an increasingly frequent outcome of motor vehicle trauma. Neurologic injury after such injuries can be a cause of significant morbidity. The available literature on neurologic injuries was reviewed and compared with a clinical review of 90 unstable pelvic injuries treated during a 3-year period. Eighty-three patients were available for followup examination. Neurologic injuries were seen in 21 % of the patients. Thirty-seven percent of patients had sensory deficits alone whereas the remaining 63% had motor and sensory findings. All patients showed some evidence of neurologic recovery at an average or 24-months followup. At least 1 grade of muscle function improvement was consistently seen and 53% of patients had complete neurologic recovery. Improvement in function was seen as many as 24 months postinjury, but L5 function was least likely to progress to full recovery. The incidence of neurologic injuries and their distribution was similar to that reported in the literature, whereas the prognosis for neurologic recovery was significantly better. This may be related to techniques of early anatomic reduction and stabilization of unstable pelvic ring injuries.
From April 1982 to August 1995, the author treated 127 patients with pelvic ring injuries by open reduction and internal fixation within 3 weeks of injury. Fifty-five (43%) patients (none of whom had a symphysis dislocation) had posterior internal fixation without anterior pelvic internal or external fixation. In 37 patients (29%) anterior and posterior internal fixation was performed whereas 35 patients (28%) were treated by anterior internal fixation alone. Plates and screws were used for all anterior fixations. Bladder or urethral injury was not considered a contraindication to anterior internal fixation. Of 109 patients who were observed until union of their fractures, 3 required a repeat surgery because of loss of reduction or failure of fixation or both. All 3 patients maintained reduction and healed after the second intervention. Of 72 anterior internal fixations, 1 deep infection was the only surgical complication. A single plate is reliable for fixation of the symphysis pubis and when necessary, the superior pubic ramus. However, even in displaced and unstable pelvic ring injuries, most fractures of the pubic rami do not require stabilization by internal or external fixation. Eighty-eight of 105 fractures of the obturator ring were not internally fixed and none required subsequent treatment for nonunion or loss of reduction; nor did their initial instability cause failure of posterior fixation. Internal fixation of the anterior pelvic ring, though safe and reliable, should be reserved for symphysis pubis dislocations and only a minority of pubic ramus fractures.
One hundred and seven unstable pelvic fractures were treated operatively. Reductions were graded by the maximal displacement measured on the 3 standard views of the pelvis. Criteria were: excellent 4 mm or less, good 5 to 10 mm, fair 10 to 20 mm, and poor more than 20 mm. Overall there were 72 excellent, 30 good, 4 fair, and 1 poor reduction. Ninety-five percent of all reductions were excellent or good. Open reduction and internal fixation within 21 days were associated with a higher percentage of excellent reductions than in reductions performed after 21 days (70% versus 55%). These differences were not statistically significant, however. Complications were infrequent using the techniques described.
Twenty-nine patients with unstable rotational injuries treated operatively were observed for an average of 39 months. There were 24 associated orthopaedic injuries. Twenty-seven patients had symphysis disruption (4 with rami fractures) and 2 had rami fractures associated with an acetabular fracture. Followup evaluation of those who could be evaluated in each category revealed that 96% had no pain or pain only on strenuous activity, ambulated without assistance or limitations, and returned to work. Open reduction and internal fixation of rotationally unstable pelvic fractures results in a high functional success rate.
Forty-six patients with 48 operatively fixed unstable posterior pelvic ring disruptions were observed for an average of 44 months. Two thirds of the patients returned to their original jobs and 16% changed jobs because of an associated injury. Sixty-three percent of the patients had no pain or pain only on strenuous activity and ambulated without limitation. However, 35% of the patients had significant neurologic injuries that compromised their final result. Properly performed open reduction and internal fixation of unstable posterior pelvic ring injuries may he expected to yield good functional results in the majority of patients. Associated injuries continue to be a major source of disability.
From 1984 to 1995, 37 patients with nonunion, malunion, and combined nonunion malunion of the pelvic ring were treated. Included among the patients were many different initial injury patterns and subsequent variable combinations of malunion and malpositioned nonunion. The typical surgical repair was performed in multiple stages and often created uniquely to solve a patient's particular problem. Thirty-two of 37 patients were satisfied with their outcome, although 19% of the patients suffered complications.
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The authors present a new technique for fusion of the hip joint through an anterior approach (Smith-Petersen) with the use of a ventral plate and a lateral compression screw. The indications for fusion of the hip joint are discussed and some cases are presented. The advantages of this technique are that strong bone stock for fixation is used on the pelvic side, that the abductor muscles and vascularization of the femoral head are left intact, and that no external fixation (cast) is routinely used for after-treatment.