[Primary strength of conventional and alternative suture techniques of the rotator cuff. A biomechanical study]. / Uber die Primärfestigkeit konventioneller und alternativer Nahttechniken der Rotatorenmanschette. Eine biomechanische Untersuchung.

The aim of this biomechanical study was to evaluate rotator cuff repair strength using different suture anchor techniques compared to conventional repair, taking into consideration the native strength of the supraspinatus tendon. Therefore, a defined defect of the supraspinatus was created in 50 freshly frozen cadaver specimen (group size n = 10; median age at death: 56 years). Five methods were employed for cuff repair: standard transosseous suture, modified transosseous suture with patch augmentation and three suture anchors (Acufex Wedge TAG, Acufex Rod TAG und Mitek GII). The maximum tensile load of the five techniques was: standard transosseous suture, 410 N; modified transosseous suture, 552 N; Wedge TAG, 207 N; Rod TAG, 217 N; Mitek GII, 186 N. The difference between the suture anchor and standard techniques were highly significant (P < 0.001). In this series, the Mitek Gll anchor showed the lowest anchor dislocation rate at 3% (n = 1). The Wedge TAG system had a dislocation rate of 27% (n = 8) and the Rod TAG system 43% (n = 13). Suture anchor techniques revealed about 20%, the standard technique 34% and its modification 60% of the hypothetically calculated native tendon strength. Compared to conventional transosseous suture techniques, the use of the suture anchors tested in this series does not significantly increase the primary fixation strength of rotator cuff repair. The metallic implant with two barbs (Mitek GII) seems to be superior to the polyacetal anchors when inserted into the spongiform bone of the greater tubercle. The considerably weaker repair strength needs to be taken into consideration in postoperative patient rehabilitation, especially after the use of suture anchors.

[Tensile strength of the tendon of the supraspinatus muscle in the human. A biomechanical study]. / Die native Reissfestigkeit der Sehne des M. supraspinatus beim Menschen. Eine biomechanische Untersuchung.

The traumatic tear of the rotator cuff has been discussed very intensively for a long time despite the fact that there do not exist representative objective data about the native tensile strength of these tendons. The aim of this study was to evaluate the age related native strength of the supraspinatus tendon. 25 fresh frozen cadaver specimen (age: 23-94, 24 h post mortem, 18 male, 7 female) were tested using so called cryojaws for soft tissue fixation. The results showed the major part of the tensile forces to be transmitted through the anterior thicker part of the tendon (e.g. 14 bony avulsions in this area). We found significant correlations between age and maximum strength (p < 0.001), age and stiffness of the tendon (p < 0.005) and stiffness and maximum strength (p < 0.001). These results show that tensile strength and stiffness of the supraspinatus tendon decrease with age. However, a 65 year old specimen still demonstrates a weight bearing structure (about 900 N maximum tensile strength) and is not necessarily ruptured or degeneratively altered.

Long-term results of forefoot arthroplasty in patients with rheumatoid arthritis.

Disabling forefoot deformity of rheumatoid origin frequently requires surgical intervention. Twenty-three patients (36 feet) who underwent excision of the metatarsal heads in our unit between 1980 and 1987 were assessed clinically and radiologically (n = 12) and by questionnaire (n = 11) at an average 10.5 years (range: 4 to 15) following surgery. Although the procedure was initially successful at the time of review, the result was classified as unsatisfactory because of restriction of walking ability due to pain in the forefoot area in 56% of patients. Recurrence of the deformity--more frequently involving the great toe--had occurred in 72% of patients, and painful callosities were present in 61%. In the patients examined clinically and radiologically, unsatisfactory results were due mainly to mal-alignment of the great toe and extensor tendon tightness. Hindfoot deformity also significantly contributed to pain in the forefoot area. Diminished arthroplasty space, irregular resection cascade, and development of bony spikes were frequently associated with recurrence and callosities. The result of forefoot arthroplasty deteriorates with time. Failure to maintain a plantigrade great toe, intrinsic weakness, and hindfoot deformity were the main factors contributing to an unsatisfactory result.

Development of a double antibody radioimmunoassay for quantitation of 1 alpha,25-dihydroxyvitamin D.

A sensitive radioimmunoassay (RIA) for 1 alpha,25-dihydroxyvitamin D [1 alpha,25(OH)2-D] with a double antibody (DAB) separation technique to separate free from bound antigen has been developed. The hormone was extracted from 1 ml serum or plasma by Extrelut columns and normal phase high performance liquid chromatography and quantitated in the DAB-RIA. The detection limit of the assay was 3.75 ng/l. The intraassay variation coefficients were 15.9% and 10.5% for samples with 1 alpha,25(OH)2D3 concentrations of 54 ng/l and 130 ng/l, respectively. The interassay variation coefficients were 18.0% and 16.7% for these two concentrations. Mean (and SD) values for 1,25(OH)2D in serum of 40 healthy subjects and 38 patients with chronic renal failure who did not receive 1,25(OH)2D3 were 62.8 ng/ml (22.2) and 12.4 ng/ml (9.8), respectively. The mean value for 7 patients with primary hyperparathyroidism was 66.5 ng/ml (35.8) before surgery. These results compared well with those of an established charcoal-based RIA. Compared to charcoal-based RIAs, the DAB-RIA is faster and requires less laborious assay procedures.