Lars-Åke Broström

Muscle activity and coordination in the normal shoulder. An electromyographic study

Muscle activity and coordination in ten shoulders were studied in five healthy subjects using electromyography (EMG) recorded during standardized loaded movements, i.e., flexion, extension, abduction, external rotation, and internal rotation at 0 degrees, 45 degrees, and 90 degrees of abduction. Bipolar surface and intramuscular fine-wire electrodes were used, and the EMG signal was low-pass filtered, full-wave rectified, and time-averaged. Activity from the subscapularis, supraspinatus, infraspinatus, pectoralis major (sternoclavicular part), the anterior, middle, and posterior parts of the deltoid, and the latissimus dorsi was recorded in parallel. In order to allow a comparison of the activity in a subjects different muscles and the activity in specific muscles between different individuals, the EMG was normalized. Muscle activity occurred simultaneously in muscles producing the movement and in antagonistic muscles. Coordination due to muscle contractions plays a significant role in stabilizing the shoulder joint. The infraspinatus, subscapularis, and latissimus dorsi acted as stabilizers during flexion; the subscapularis acted as a stabilizer during external rotation and with the supraspinatus during extension.

Differences in shoulder muscle activity between patients with generalized joint laxity and normal controls.

The aim of the present study was to analyze shoulder muscle activity in patients with generalized joint laxity and shoulder instability and to compare it with muscle activity recorded in healthy subjects from an earlier study. Electromyographic (EMG) activity was recorded from eight shoulder muscles in six patients using surface and intramuscular fine-wire electrodes. Recordings were made from the subscapularis, supraspinatus, infraspinatus, pectoralis major (sternoclavicular part), the anterior, middle, and posterior parts of the deltoid, and the latissimus dorsi. The EMG signal was low-pass filtered, full-wave rectified, and time-average. Normalization of the EMG allowed interindividual and intraindividual comparisons. During abduction and flexion, muscle activity in the anterior and middle parts of the deltoid was significantly decreased in the patients, and during internal rotation activity in the subscapularis was increased. As in healthy subjects, patients showed simultaneous activity in both those muscles producing the movement and in the antagonistic muscles. The altered muscle activity observed in patients with generalized joint laxity provides (1) a basis for understanding the mechanism of their shoulder instability and (2) the rationale for a physical training program for these patients.

Healing complications after internal fixation of trochanteric hip fractures: the prognostic value of osteoporosis.

Summary: In a 3-year prospective randomized trial, the prognostic value of osteoporosis in terms of predicting healing complications due to implant failures or loss of fracture reduction has been studied in 113 patients with intertrochanteric hip fractures treated with either a sliding screwplate or Ender nailing. According to the Barnet and Nordins osteoporosis index, 66 patients were considered to have moderate or severe osteoporosis. There were no differences between patients with or without osteoporosis as regards the number of fractures with collapse in varus >10°, redislocation >10 mm, or compression exceeding 10 mm. Six months after surgery, 48 patients failed in healing or healed with complications. These cases disclosed increased osteoporosis in comparison with those showing noncomplicated healing. Patients with osteoporosis who had unstable fractures treated by Ender nailing were found to have the worst prognosis for healing complications (p=0.006). Of the 33 fractures with implant failures, 25 (76%) occurred in patients with osteoporosis (p=0.04). In patients with osteoporosis, the frequency of mechanical failures was significantly higher in fractures with the device positioned incorrectly. Independently of the device used, patients with unstable trochanteric hip fractures and osteoporotic bone were the group with the highest risk for failures of the implant.

Scaphoid nonunion treated with the Matti-Russe technique: long-term results

Forty-three patients with scaphoid pseudarthrosis were surgically treated using the Matti-Russe technique. Twenty-seven patients were examined seven to 17 years after surgery (mean, 12 years). The interval between trauma and operation of the pseudarthrosis was 40 months. Before operation, all patients were unable to do any work because of pain. Fracture healing was observed in 22 cases (81%). Radiocarpal osteoarthrosis was present in 18 cases, compared with eight before operation. Radial deviation and extension was impaired, and pronation and supination was unaffected, compared with the healthy side. Twenty-four patients were satisfied with the operative result and none felt worse. All patients but one could return to work. The Matti-Russe method proved satisfactory in 24 of 43 patients available for long-term follow-up evaluation.

Survival in osteosarcoma in relation to tumor size and location.

To evaluate the outcome for osteosarcoma patients treated with different forms of adjuvant therapy in nonrandomized series, it is important to realize the possible influence of different prognostic factors. In two series of patients with primary classic osteosarcoma, survival was analyzed in relation to tumor size and site. In the first series comprising 57 patients, no adjuvant therapy was given and the five-year survival rate for all patients was 19%. A significantly (p less than 0.01) higher survival rate (43%) was noted for patients with tumors distally located and less than 0 cm in size (as measured by their largest diameter on radiograms), as compared to 12% for patients with larger and proximally located tumors. These figures were the same at three-and five-year follow-up. In the second series, comprising 22 patients, all received adjuvant interferon treatment. The three-year survival rate was 68%, and the five-year survival rate for the 12 patients followed was 58%. The survival rate for patients with tumors distally located and less than 10 cm in size was 88%, as compared to 57% for patients with larger and proximally located tumors. In the interferon series, tumor size appeared more important than location.

Growth and ploidy of human osteosarcoma xenografts in serial passage in nude mice

Six human osteosarcoma tumors have been transplanted to and maintained as xenografts in serial passage in nude mice. The xenografts, characterized by growth rate, histologic appearance, and DNA flow cytometric data, are now in the 6-17 passages in mice. Histologic appearances and growth rates of the xenografts were unchanged through all passages except for one xenograft in which the growth rate doubled in passage 3. All six tumors had hyperploid DNA contents. The ploidy levels were unchanged, compared to their original tumors, in all passages of five xenografts. One xenograft, concomitantly with the increase in growth rate, also doubled the ploidy from 2.8 to 5.6C. There was a good agreement between the proportion of S-phase cells and mitotic indices of the six xenografts. The growth rate, depending also on cell loss, was less related to the proliferative activity of the xenografts. It was concluded that osteosarcomas have a stable aneuploid DNA content in nude mice, but polyploidization can occur after a number of passages.

Knee motion after tibial osteotomy for arthrosis: Kinematic analysis of 7 patients

The in vivo kinematics of the knee in 7 patients with moderate medial gonarthrosis was analyzed before and 6 months after high tibial osteotomy using roentgen stereophotogrammetric analysis. The inclination of the femorotibial helical axis of rotation did not change with knee flexion or after surgery. The femorotibial rotation increased after surgery. No consistent change in patellar position after surgery was found. Patella translated laterally as the knee was flexed with a maximum patellar translation of about 15 mm and rotated internally with a maximum patellar internal rotation of about 15 degrees. There was no significant change in patellar translation or rotation after surgery. There was a good concordance regarding the size of the tibial wedge removed during surgery, calculated from the Hip-Knee-Ankle radiographs and from the roentgen stereophotogrammetric measurements.

Correlation between lymphocyte-mediated auto-tumor reactivities and the clinical course

SummaryT-cell-enriched blood lymphocyte populations from 24 osteosarcoma and 22 soft-tissue sarcoma patients were assayed at the time of surgery for proliferative response to, and/or cytotoxic potential against autologous tumor cells. Tumor-free period and survival of the patients were correlated with the results obtained in the in vitro tests. The observation time was between 18 and 118 months (mean 62) for the osteosarcoma patients and between 18 and 72 (mean 42) for the patients with soft-tissue sarcoma. In both groups tumor-free period and survival were longer for those individuals who had auto-tumor reactivity. In the non-reactive group, all patients died within 3 years. Almost all patients had cytotoxicity against K562.

Can historical controls be used in current clinical trials in osteosarcoma? Analysis of prognostic factors

Abstract A comparison with respect to possible prognostic factors has been made between a contemporary group of 44 patients with osteosarcoma in Sweden, who received treatment since 1971, and a historical group of 35 such patients treated prior to 1972. Only patients with no evidence of metastases on admission were included in the material. The case histories were reviewed by a team of pathologists and clinicians with experience of bone tumors, each case history was analyzed in detail and re-evaluated. The female/male ratio was lower, but not significantly so, for the contemporary group, 1:2.4, than for the historical group, 1:1.7. The mean age was similar in the two groups (18 and 17 years, resp.) Pain was the most common symptom in both groups, it was recorded in 86 and 100% in the contemporary and historical groups, respectively. Although the patients of the historical group generally presented more symptoms, the durations were similar in the two groups (3 months). The site patterns differed slightly, although not significantly so, in the two groups, there was a higher ratio of frequency of femoral and lower leg tumors for the historical group (54 and 32%, resp.) than for the contemporary group (36 and 45 %, resp.). The variability in tumor size was greater for the historical group, as was the tumor diameter (13 and 9 cm, resp.). The historical group had a greater proportion of osteoblastic tumors (83 and 63%, resp.) and these tended to be more malignant (Grade IV:80 and 68%, resp.). The study disclosed differences between the contemporary and the historical groups in respect to various factors that previous studies indicated might have a bearing on the prognosis in osteosarcoma. On the whole the prognosis would be expected to be less favorable for the historical group and there would seem to be a definite risk in using this group as a control group to the adjuvant interferon treated patients. Similar reviews of other non-randomized current clinical series would be a valuable aid in determining the efficacy of adjuvant therapy.

Acute compartment syndrome in forearm fractures

Sixteen patients were reexamined 2 to 5 years after surgical treatment of acute compartment syndrome in forearm fractures. High-energy trauma was the casual factor in 11 cases, in 5 of which there was an open fracture with skin defect. Fracture stabilization and fasciotomy of forearm and carpal compartments were performed as emergency procedures. The time for fracture healing averaged 8 weeks. Median nerve function was impaired in all the patients, and the ulnar nerve function in 8. The median nerve recovered completely in 15 patients, but ulnar nerve function was still impaired in 2 patients, 1 of whom had a nerve tissue defect. Eight patients could resume their occupation within a year.