Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques

BACKGROUND: Our hypothesis that multiple, equally tensioned strands of hamstring graft used for reconstruction of the anterior cruciate ligament are stronger and stiffer than ten-millimeter patellar ligament grafts was tested biomechanically with use of tendons from cadavera. METHODS: In the first part of the study, we measured the strength and stiffness of one, two, and four-strand hamstring grafts, from fresh-frozen cadaveric knees, that had been tensioned equally when clamped. In the second part of the study, we compared four-strand grafts to which tension had been applied by hand and then clamped with similar grafts to which tension had been applied with weights and then clamped. The grafts for the two experiments were obtained from thirty-four paired and ten unpaired knees. We also studied the effects of cooling on the biomechanical properties of grafts by comparing patellar ligament grafts tested at 13 degrees Celsius with those tested at room temperature. RESULTS: Two equally tensioned gracilis strands had 185 percent of the strength and 210 percent of the stiffness (1550+/-428 newtons and 336+/-141 newtons per millimeter, respectively) of one gracilis strand (837+/- 138 newtons and 160+/-44 newtons per millimeter, respectively). Two equally tensioned semitendinosus strands had 220 percent of the strength and 220 percent of the stiffness (2330+/-452 newtons and 469+/-185 newtons per millimeter, respectively) of one semitendinosus strand (1060+/-227 newtons and 213+/-44 newtons per millimeter, respectively). Four combined strands (two gracilis strands and two semitendinosus strands) that were equally tensioned with weights and clamped had the additive tensile properties of the individual strands. With the numbers available, four combined strands that were manually tensioned and clamped were not found to be significantly stronger or stiffer than two semitendinosus strands that were equally tensioned with weights (p>0.07). CONCLUSIONS: Four combined strands that were equally tensioned with weights and clamped were stronger and stiffer than all ten-millimeter patellar ligament grafts that have been described in previous reports. All strands of a hamstring graft must be equally tensioned for the composite to have its optimum biomechanical properties. CLINICAL RELEVANCE: Because of the well recognized donor-site morbidity associated with the use of patellar ligament grafts for reconstruction of the anterior cruciate ligament, multiple-strand hamstring-tendon grafts have become an increasingly popular choice. Our data demonstrate that equally tensioned four-strand hamstring-tendon grafts have initial tensile properties that are higher than those reported for ten-millimeter patellar-ligament grafts; thus, from a biomechanical point of view, they seem to be a reasonable alternative.     

Detection of adenocarcinoma by urinary microsatellite analysis after augmentation cystoplasty

Augmentation cystoplasty is associated with an increased risk of bladder cancer development between 10 and 20 years after augmentation. Using microsatellite analysis, we analyzed urine obtained before surgical resection of the malignant lesion from a patient who developed invasive adenocarcinoma after augmentation cystoplasty. Loss of heterozygosity was identified in both urine and tumor samples from this patient. This observation suggests that microsatellite urine analysis may be useful as a monitoring tool for patients after augmentation cystoplasty.     

Cerebrospinal fluid oligoclonal IgG bands in patients with spinal arteriovenous malformation and structural central nervous system lesions

OBJECTIVE: To investigate the incidence and characteristics of patients with structural central nervous system (CNS) lesions and cerebrospinal fluid oligoclonal IgG bands. DESIGN: A retrospective study. METHOD: The medical records of patients with cerebrospinal fluid oligoclonal IgG bands were evaluated for the presence of structural CNS lesions, their location and cause, and for clinical characteristics. SETTING: Cerebrospinal fluid oligoclonal IgG bands were examined in the Neuroimmunology Laboratory, Hadassah University Hospital, Jerusalem, Israel. PATIENTS: Two hundred seventy of 570 patients with positive cerebrospinal fluid oligoclonal IgG bands were available for analysis. Twenty patients had structural CNS lesions. RESULTS: Twenty (7.5%) of the 270 patients had structural CNS lesions: 3 patients had spinal arteriovenous malformation; 5 patients had tumors; 9 patients had compressive cervical myelopathy. Traumatic leukomalacia, Arnold-Chiari malformation type 1, and CNS hemosiderosis were present in 1 patient each. In 2 patients (1 patient with recurrent meningioma and 1 patient with posttraumatic encephalomalacia) the presence of a structural CNS lesion was followed by the development of multiple sclerosis. In all 3 patients with spinal arteriovenous malformation, oligoclonal IgG identification prolonged the time to diagnosis and therapy, which varied from a few weeks to 3 years. CONCLUSIONS: Structural CNS lesions, responsible for the neurological disorder, were present in 20 patients (7.5%) with cerebrospinal fluid oligoclonal IgG bands. The mechanism underlying oligoclonal IgG presence in spinal arteriovenous malformation and the coexistence of multiple sclerosis and structural CNS lesions is unknown, but may be related to recurrent tissue damage with repeated presentation of CNS antigens to the immune system.     

Growth monitoring with the British 1990 growth reference

AIM: To provide a simple method for assessing centile change based on the British 1990 growth reference. STATISTICAL METHOD: The change in SD score over a period of time has SD square root of 2(1-r), where r is the correlation between the first and second SD score. This leads to an SD score for centile change. DATA: Annual height measurements from 2 to 9 years for 318 children from the French longitudinal growth study. RESULTS: The correlations between heights at different ages are higher for shorter measurement intervals and at older ages. The chance of a child's height centile falling one centile band width is correspondingly smaller for shorter measurement intervals and at older ages. An increase in height measurement error reduces the correlations and dramatically increases the chances of centile crossing. CONCLUSIONS: Quantitative height monitoring based on centile change is provided for whole year periods between 2 and 9 years of age. Effective monitoring requires the measurement error to be as small as possible.     

Adult height in patients with childhood onset atopic dermatitis

Cross sectional studies have reported impaired growth in children with atopic dermatitis. If this growth impairment is irreversible, it would be expected to adversely influence final height attainment. The standing heights and other anthropometric parameters were assessed in 35 adults with onset of atopic dermatitis before 5 years of age and a control group of 35 adults with adult onset contact dermatitis or psoriasis. There was no significant difference in the standing height SD score, mid-parental height SD score, sitting height SD score, subischial leg length SD score, nor body mass index between the atopic dermatitis and control groups. The standing height SD score was not significantly different among: (a) patients with atopic dermatitis affecting less than 50% of their body surface area and those with greater than 50% affected; (b) patients using the four different potency topical corticosteroids; and (c) patients with atopic dermatitis without asthma and those with coexisting asthma. It is concluded that short stature is not a feature of our group of adult patients with onset of atopic dermatitis before 5 years of age, continuing into adulthood, and severe enough to require specialist care. This suggests that if growth impairment occurs in childhood, it is likely to be temporary and reversible.