Faculty Bibliography

We studied the biomechanical behaviour of three sliding fixation devices for trochanteric femoral fractures. These were a titanium alloy sideplate and lag screw, a titanium alloy sideplate and dome plunger with cement augmentation, and a stainless-steel sideplate and lag screw. We used 18 mildly osteoporotic cadaver femora, randomly assigned to one of the three fixation groups. Four displacement and two strain gauges were fixed to each specimen, and each femur was first tested intact (control), then as a two-part fracture and then as a four-part intertrochanteric fracture. A range of physiological loads was applied to determine load-bearing, load-sharing and head displacement. The four-part-fracture specimens were subsequently tested to failure to determine maximum fixation strengths and modes of failure. The dome-plunger group failed at a load 50% higher than that of the stainless-steel lag-screw group (p < 0.05) and at a load 20% higher than that of the titanium-alloy lag-screw group (NS). All 12 lag-screw specimens failed by cut-out through the femoral head or neck, but none of the dome-plunger group showed movement within the femoral head when tested to failure. Strain-gauge analysis showed that the dome plunger produced considerably less strain in the inferior neck and calcar region than either of the lag screws. Inferior displacement of the femoral head was greatest for the dome-plunger group, and was due to sliding of the plunger. The dome plunger with cement augmentation was able to support higher loads and did not fail by cut-out through the femoral head.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-six hemiarthroplasties were performed for acute three- and four-part proximal humerus fractures between March 1986 and December 1991. Postoperative pain, active range of motion, and function were evaluated in 22 patients at a mean follow-up period of 30 months (range 12 to 66 months) with the American Shoulder and Elbow Surgeons evaluation form. Seventy-three percent of patients reported only slight or no pain. Active forward elevation averaged 107 degrees, external rotation averaged 31 degrees, and the average internal rotation was to the second lumbar vertebra. Strength and stability were rarely problematic. Seventy-three percent of patients reported difficulty with at least three of 15 functional tasks tested. Lifting, carrying a weight, and using the hand at or above shoulder level were the most common limitations. This study indicates that hemiarthroplasty for acute three- and four-part fractures generally can be expected to result in painfree shoulders. However, recovery of function and range of motion are much less predictable

Three hundred thirty-six community-dwelling, previously ambulatory, geriatric patients with hip fracture were observed prospectively to determine ambulatory ability at a minimum followup of 1 year. One hundred thirty-seven (41%) patients maintained their prefracture ambulatory ability at a minimum followup of 1 year; 134 (40%) patients remained ambulatory but became more dependent on assistive devices; 39 (12%) previous community ambulators became household ambulators, and 26 (8%) patients became nonfunctional ambulators. Analysis was performed to determine which pre- and postinjury factors were predictive of failure to recover ambulatory capacity 1 year after fracture. Potential predictor variables analyzed included age, gender, number of comorbid conditions, prefracture ambulatory ability, prefracture living situation, fracture type, American Society of Anesthesiologists rating of operative risk, type of surgery, and number of postoperative complications. Multiple logistic regression analysis identified significant contributions of age, prefracture ambulatory ability, American Society of Anesthesiologists rating of operative risk, and fracture type to ambulatory recovery

The incidence of full thickness rotator cuff tears was determined after careful dissection and inspection of 235 male and female cadavers ranging in age from 27-102 years with an average age of 64.7 years. A total of 456 shoulders were examined. Partial thickness tears were excluded from the study. Seventy-eight shoulders, 17% (53 female, 26 male) were found to have full thickness tears. The average age of those cadavers with tears was 77.8 years as compared to 64.7 years in the intact group. The incidence of full thickness tears was also found to increase with increasing age. In cadavers under 60 years of age the incidence of rotator cuff tears was 6% as opposed to 30% in those over 60 years of age

The orthopaedic surgeon has a multitude of internal fixation devices and techniques available for use in the treatment of subtrochanteric fractures of the proximal femur. The successful use of second-generation locking nails is technically demanding. Close attention to positioning of the patient, reduction of the fracture, placement of the guide-wire, and insertion of the nail and of the proximal and distal locking screws is mandatory. The newer, high-strength hip-screws allow good fixation of a fracture that extends into the piriformis fossa. If medial comminution is present, this technique is best performed in conjunction with indirect reduction and bone-grafting. With proper technique, these devices allow the surgeon to manage predictably a complex subtrochanteric fracture that previously had to be treated with traction or extensive dissection and with (frequently inadequate) internal fixation

Between January 1, 1987, and December 31, 1992, 140 community-dwelling geriatric patients > or = 65 years of age with a displaced femoral neck fracture (Garden III-IV) underwent primary prosthetic replacement and were followed prospectively for a minimum of 1 year. Overall, 92 patients received a cemented bipolar prosthesis and 48 patients received a cemented modular unipolar prosthesis. There were no statistically significant differences between the two groups with respect to preinjury characteristics (age, sex, and number and severity of medical comorbidities) and functional ability. There were no statistically significant differences between the two groups with regard to the number of postoperative complications, length of stay, and 1 year mortality rate. An in-depth functional evaluation was obtained as follows: level of ambulation, independence in basic activities of daily living (feeding, bathing, dressing, toileting), and independence in instrumental activities of daily living (food shopping, food preparation, banking, laundry, housework, and use of public transportation). At 1 year follow-up, no statistically significant differences in functional ability were identified between the unipolar and bipolar groups. Furthermore, at a minimum of 1 year follow-up, there were no statistically significant differences between the two groups with regard to the need for revision surgery or the incidence hip pain. Based on the results of this study, there does not appear to be any advantage to the use of bipolar endoprosthesis for the treatment of femoral neck fractures in the elderly patient. The lower cost of modular unipolar prostheses compared with bipolar prostheses provides additional support for their use

A clinical and histological study was performed on fracture blisters found in association with 13 surgically treated ankle fractures. The timing of surgery was dependent upon soft tissue swelling; the status of the blister did not affect this aspect of the decision making process. The average time from injury to surgery was 2.1 days (range, 1-3 days). At the time of surgery all blisters were intact. Skin biopsies were obtained from the edge of the incision in proximity to the blister, and from the bed of the blister when the incision was made through the blister. Clinically, 2 blister types were identified: (1) clear fluid filled, and (2) blood filled. Histologically, both blister types demonstrated a cleavage injury at the dermoepidermal junction. However, the dermis of the clear fluid filled blister retained occasional epithelial cells, while the dermis of blood filled blisters was completely devoid of epidermis. Minimal to no evidence of dermal injury was found in histologic sections from the blister beds or from the skin in close proximity to blisters. All incisions made through and around skin blisters went on to heal without evidence of infection or wound breakdown. Delayed wound healing occurred in 1 patient in whom an incision was placed through a blood filled blister. The blood filled blister appears to represent a slightly deeper injury than the clear fluid blister and had a higher risk of poor healing of surgical incisions

Fifty embalmed human tibias were osteotomized to create a simulated vertical shear (supination-adduction) fracture of the medial malleolus and were stabilized using one of five internal fixation techniques. In offset axial testing, which simulated supination-adduction loading, the fixation strength of tibias stabilized with either cortical or cancellous lag screws placed perpendicular to the osteotomy was over five times greater than the strength of those treated with an antiglide plate and nearly two and a half times greater than those treated with cancellous lag screws placed oblique to the osteotomy. The tibias stabilized with cancellous lag screws placed perpendicular to the osteotomy exhibited twice the fixation strength of the tibias stabilized with an antiglide plate and distal lag screw. The tibias stabilized with an antiglide plate and distal lag screw and perpendicularly placed cortical or cancellous lag screws demonstrated three times greater resistance to displacement to the applied supination-adduction load than those stabilized with an antiglide plate alone. In offset transverse testing, to simulate loading in external rotation, the mean failure load of the tibias stabilized with cancellous lag screws placed perpendicular to the osteotomy was over two and a half times greater than those stabilized with an antiglide plate and distal lag screw. No significant differences were observed in the resistance to displacement for these tests. These results support the use of lag screws placed perpendicular to the fracture surface for stabilization of vertical shear fractures of the medial malleolus and indicate that the use of an antiglide plate, with or without a distal lag screw, does not offer any advantage over lag screw fixation

A biomechanical cadaver study was performed to compare the stability and ultimate strength of 3 standard fixation techniques used for treatment of basicervical hip fractures. Twenty one pairs of mildly osteoporotic femurs were selected, based on a computed tomography bone density reading of 40-50 Hounsfeld units and a Singh index of III. After initial mechanical characterization of intact femurs, basicervical femoral neck fractures were created, reduced, and then instrumented with random assignment to 1 of 3 methods of fixation: (1) 3 parallel 6.5-mm cannulated cancellous screws; (2) a 135 degrees sliding hip screw with a 4 hole side plate; and (3) a 135 degrees sliding hip screw with a 4 hole side plate and a 6.5-mm cannulated cancellous screw placed proximal and parallel to the sliding screw. Nine pairs were tested to failure in axial loading, 6 pairs in lateral bending, and 6 pairs in torsion. The group instrumented with the multiple cancellous screws had a significantly (p < 0.01) lower ultimate axial load to failure than either sliding hip screw group. However, the multiple screws demonstrated significantly (p < 0.01) less fracture displacement. There were no statistically significant differences in lateral bending or torsional testing behavior between the 3 fixation methods. Use of the sliding hip screw is recommended rather than use of multiple cancellous screws for treatment of basicervical femoral neck fractures. Although a superiorly located cancellous screw may provide rotational control during sliding hip screw insertion, it provides no incremental fixation after the sliding hip screw is placed

Fourteen patients with Stage II or III impingement syndrome (average age 58 years) were studied. Nine patients had full-thickness rotator cuff tears documented by arthrograms. Patients initially underwent a thorough shoulder examination followed by baseline isokinetic strength testing. Abduction/adduction testing was performed utilizing a Biodex dynamometer. Maximum concentric contractions were performed, and values for peak torque (PT), total work (W), and power (P) were obtained. All patients received a subacromial injection of 5 cc 1% lidocaine plus 5 cc 0.5% bupivacaine (Marcaine). After 5 minutes the testing sequence was repeated. Clinically, patients demonstrated marked improvement following injection. Eighty-six percent reported complete pain relief; the remaining two patients reported only mild discomfort at the extremes of motion. Improvement in functional activity of the affected shoulder was noted by all subjects. On manual muscle testing, 13 of 14 patients (93%) demonstrated increased abduction strength; 11 of 14 (79%) had improvement in external rotation. Mean increases in active forward elevation and external rotation were 36 degrees and 11 degrees, respectively (P < .01). Postinjection isokinetic changes in PT, W, and P for abduction/adduction were dramatic. For abduction, all patients showed significant increases in P (mean 82%), W (mean 90%), and PT (mean 48%) (all P < .05). No significant differences in range of motion testing or strength parameters were noted based on the presence or absence of a rotator cuff tear. For adduction, all patients showed significant increases in P (mean 208%), W (mean 183%), and PT (mean 41%) (all P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)