The effects of calcium on bone mineral density in postmenopausal women with colles fractures.

The increased incidence of fracture in postmenopausal women may be attributable, in part, to osteoporosis. Prediposing factors other than age include genetic constitution, physical activity, alcohol and caffeine abuse, and dietary calcium deficiency. A group of 15 postmenopausal women between the ages of 43 and 85 years were analyzed for bone mineral density within 4 weeks of an acute fracture of the distal radius. Dual photon absorptiometry scanning was performed on the first through fourth lumbar vertebrae. Results indicate that bone mineral densities below the fracture threshold (0.965 g/cm2) were seen in 9 of 15 (60%) patients. Each woman was given 1500 mg/day calcium supplementation for 1 year. At 1 year, each woman was contacted for a follow-up bone mineral density analysis. While no significant increase in bone mineral density was seen, calcium supplementation appeared to inhibit further bone loss. The results of this study support previous work which has indicated that supplemental calcium may be beneficial in combatting age-related bone loss.

Effects of anticonvulsant drug therapy on bone mineral density in a pediatric population.

Twenty epileptic outpatients, aged 5-20 years and taking either phenobarbital or phenytoin for anticonvulsant therapy, were evaluated for femoral neck area bone mineral content and bone mineral density using dual photon absorptiometry. Duration of treatment averaged 51.4 months (range, 9-124 months). A group of 20 normal children who were matched for age, sex, and race served as controls. There were no statistically significant differences between the femoral neck area bone mineral densities of the epileptic patients as compared to the controls. There were also no correlations between duration of anticonvulsant therapy and bone mineral density, nor any differences in bone mineral density values when comparing epileptic patients taking phenobarbital with those patients taking phenytoin.

An evaluation of the mechanical failure modalities of a rotating hinge knee prosthesis.

The clinical and metallurgical performance of 12 retrieved Noiles total knee prostheses was investigated. Clinical histories and serial roentgenograms were used in conjunction with the American Society for Testing and Materials (ASTM) standard implant retrieval and analysis techniques to assess device performance. All of the devices were removed because of implant loosening with pain, while two devices also had a late infection. The average time in situ for all devices was four years. Roentgenographically, all of the devices showed signs of progressive radiolucencies. Ten (83%) of the devices migrated proximally within the femur. A marked varus drift was observed in eight (67%) of the retrieved prostheses. Hypertrophy of the femoral cortex was observed in eight (67%) of the cases. Seventy-three percent of the polyethylene tibial stems exhibited extensive wear on the anterior and medial aspects of the articulating surface. Extensive wear was also seen on the anterior and extreme posterior aspects in 92% of the polyethylene tibial plateau bearings. This wear was a consequence of the migration of the femoral component leading to buttressing of the plastic components against bone or bone cement. This study indicates serious design flaws in the Noiles knee prosthesis that unless corrected would question the use of the device in either primary or revision knee surgery.

Tissue reaction to implant corrosion in 38 internal fixation devices.

The corrosion characteristics, metallurgical properties, and clinical performance of 38 retrieved internal fixation devices were correlated with the tissue reaction to these devices. Metallurgical parameters included thin and heavy inclusion content, Rockwell hardness, and grain size. The excised fibrous tissue strip was directly overlying each plate at removal and sectioned between screw-hole sites. The material studied from the 38 plates consisted of 201 screw-hole junctions with associated tissue biopsy sites. Clinical histories were obtained on all 38 patients with hardware removal. The average age at the time of plate insertion was 35.6 years (range, 4 to 75 years). Insertion diagnoses included acute trauma (35 patients), joint dislocations (two patients), and fracture nonunion (one patient). The devices included seven upper extremity bone plates, 19 lower extremity bone plates, and 12 hip screw plates. The devices remained in situ an average of 20.4 months (range, 3 to 60 months). Routine asymptomatic removals were performed on 17 of the patients, while the remaining 21 patients were symptomatic at the time of removal. Included in the reasons for symptomatic removal were pain associated with the implant (eight patients), nonunion (four patients), bursae prominence (three patients), and implant breakage (two patients). Significant correlations were found between average tissue reaction scores and average crevice corrosion scores; a trend of increasing average tissue reaction scores with increasing average screw surface corrosion scores also was observed for the 38 devices, although this relationship was not significant. Average crevice corrosion scores and average screw surface corrosion scores were highly correlated for all removals, and for the asymptomatic and symptomatic removal groups. The metallurgical parameters of thin inclusion content and heavy inclusion content also were significantly correlated for all removals, as well as for symptomatic removals. Similarly, significant correlations were found between the individual tissue reaction scores and crevice corrosion scores from the 201 individual sites, again for all devices and for the asymptomatic and symptomatic removal groups. Tissue reaction scores and time in situ showed significant correlation, with tissue reaction decreasing over time. Crevice corrosion and screw surface corrosion scores were not significantly related to time in situ. The results of this study indicate that there is considerable tissue reaction to the corrosion products of this material.(ABSTRACT TRUNCATED AT 400 WORDS)

A chronically dislocating prosthetic patella. A case report.

A 63-year-old white woman was evaluated for a chronically dislocating right patella 6 months following total knee arthroplasty. At the time of our initial evaluation, her knee would not extend beyond 35 degrees and her patella was dislocated and irreducible. At arthrotomy, when the patella was everted, the patellar component was oriented with the facet ridge rotated 90 degrees to the trochlear groove of the femoral component. The patellar template guide indicated that the fixation pegs had been drilled properly, and thus, the patellar component had been assembled improperly during manufacturing. After dome-type patellar prosthesis replacement and proximal and distal extensor realignments were performed, 2 months post-revision the patient had a range of motion from 5 degrees to 95 degrees and ambulated with no patellar instability or pain.

Trabecular bone density and menstrual function in women runners.

Osteoporosis results in decreased bone mineral mass and reduced trabecular bone density. Although its etiology remains unknown, studies have revealed differential changes in the bone mineral densities of postmenopausal women, anorexic women, and amenorrheic female athletes. Correlations have also been made between estrogen deficiency and osteoporosis in both premenopausal and postmenopausal women. In order to examine the possibility of osteopenia, a group of 36 female runners between the ages of 15 and 44 years were evaluated for bone mineral density, menstrual function, and dietary habits. Serum calcium, phosphorus, and parathyroid hormone (PTH) levels were also determined for each participant, as were complete blood counts. Using dual photon absorptiometry, all participants underwent a 20 minute scan of the lumbar spine with specificity to the L1-14 vertebrae. The 36 subjects included 19 oligomenorrheic and 17 eumenorrheic women. Results of bone density analyses revealed that the oligomenorrheic runners had significantly lower calibrated bone mineral density (CBMD) than their eumenorrheic counterparts (P less than or equal to 0.01). Likewise, the PTH levels of the oligomenorrheic runners were also significantly lower (P less than or equal to 0.01). Analysis of dietary logs revealed no significant differences between the dietary habits, the calcium intake, or the caloric intake of the two groups. The data from this study indicate that there is a relationship between reduced serum PTH levels and the oligomenorrheic state. The loss of the protective effect of estrogen in the oligomenorrheic runners possibly contributed to their reduced bone mineral densities and could be a contributing factor in osteopenia.

Association of bone mineral density and pediatric fractures.

Bone mineral density in the lumbar spine and the left femoral neck was measured for a group of 17 children, 3-14 years of age, who had sustained traumatic fractures. Children with any signs of metabolic bone disease were excluded from the study. Identical measurements were made on an age- and sex-matched control population using dual photon absorptiometry. Analysis of bone mineral measurements revealed that there were no statistically significant differences between the lumbar and femoral neck densities of the two groups. The results indicate that reduced bone density is unlikely to play a significant role in acute traumatic pediatric fractures.

The in vivo performance of 250 internal fixation devices: a follow-up study.

The in vivo performance of 250 retrieved internal fixation plates was evaluated. The corrosion characteristics and metallurgical properties of each implant were assessed and correlated with respective clinical performance. Screw-plate interface corrosion and screw surface corrosion were graded; Rockwell hardness, grain size, thin inclusion content, and heavy inclusion content measurements were made. The devices studied included 169 bone plates, 59 Richards type hip screw-plates and 22 Jewett type hip nail-plates. The devices remained in situ for an average of 26.3 months, with in situ periods ranging from 1 to 192 months. The majority of the plates (50.4%) were removed due to cause-related reasons, while the remaining devices (49.6%) were removed on a routine asymptomatic basis. The primary symptomatic removal reasons consisted of implant related pain, nonunion or malunion, infection, loosening and implant breakage. Upon stereomicroscopic examination, 89% of all plates exhibited some degree of interface crevice corrosion, and 88% of all screws exhibited some degree of surface corrosion. Statistical analysis of corrosion gradings and metallurgical data revealed significant correlations between the two. As was suggested in our previous study of a limited number of implants, this study demonstrates that stricter manufacturing standards for metallurgical properties would serve to enhance corrosion resistance and improve the in vivo performance of stainless steel internal fixation devices. It is also suggested that the routine removal of all internal fixation plates after fracture healing has been achieved would reduce the occurrence of symptomatic complications, such as implant breakage, implant loosening and implant related pain.

Trabecular bone mineral density in idiopathic scoliosis.

The association of idiopathic scoliosis with an osteoporotic state has been indicated previously. The present study compared the trabecular bone mineral densities of 44 adolescent idiopathic scoliotic girls with 44 age-, weight-, sex-, and race-matched controls. Their lumbar spine and femoral neck bone mineral densities were evaluated using dual-photon absorptiometry. Radiographs and scoliotic curve data were also obtained for the experimental group. The scoliotic subjects exhibited significantly lower lumbar and femoral neck bone mineral densities than the control subjects. No effect was found with respect to treatment, degree, or progression of curvature. The results of this study indicate that there is a generalized state of osteoporosis in idiopathic scoliotic girls when compared with matched controls.

Clinical performance of endoprosthetic and total hip replacement systems.

A retrospective study of endoprosthetic replacements and total hip prostheses was undertaken to determine factors that have the greatest effect on the success or failure of femoral hip components. A total of 227 endoprostheses were inserted within the years 1970-1985. Of these, 67 components (29.5 percent) required removal for various reasons. For an endoprosthesis, the most significant factor in determining the chances of success appeared to be the initial insertion diagnosis. Patients who received an endoprosthesis for an ailment which affected only the femoral side of the joint (such as traumatic fracture) had a much lower rate of failure than those patients with disease etiologies that could affect the acetabulum (such as osteoarthritis). The opposite was found for total hip prostheses. Of the 641 total hip devices inserted, 148 (23.0 percent) required removal. The highest rate of failure among these total hip components was for those devices inserted for trauma and the lowest rate of failure was for those inserted for osteoarthritis. Age at the time of insertion also proved to be of importance when estimating a hip component's chance of survival. For both endoprosthetic replacements and total hip arthroplasties, patients younger than 50 years of age at insertion experienced a failure rate almost twice that of those patients more than 50 years of age at insertion.

Upper extremity proprioception in idiopathic scoliosis.

Twenty-three patients with idiopathic scoliosis were tested for upper extremity proprioceptive function. All subjects had documented progression of deformity, with an average curvature of 34 degrees. The average ages for scoliotics and 18 control subjects were 16.1 and 20.8 years, respectively. Controls had no spinal deformity and underwent identical test procedures. The test results showed that scoliotic subjects had significant asymmetry between right and left limbs in their threshold for detection of joint motion (p less than or equal to 0.005) and in their ability to reproduce angles to which their elbow joint had been previously positioned (p less than or equal to 0.025). Slight asymmetry also was observed in the reproduction tests of the control group (p less than or equal to 0.013); however, there was no significant asymmetry seen in this group for the threshold test. Performance of bilateral limbs was designated good and bad for both groups; the limb that performed better in proprioceptive function was designated good limb. Analysis of data showed that the scoliotics' good and bad limbs performed inferiorly in both threshold and angle reproduction tests when compared with normal controls. The results of this study imply, but do not localize, a neurologic deficit in scoliotic patients.

Metallurgical analysis of five failed cast cobalt-chromium-molybdenum alloy hip prostheses.

The clinical and metallurigical characteristics of five cast cobalt-chromium-molybdenum alloy femoral hip prostheses which failed in vivo were evaluated. The devices included: two of the Howmedica Muller-Charnley design, two of the Howmedica Charnley design, and one of the Zimmer Aufranc-Turner design. Fractographic analyses demonstrated that the five devices had failed by fatigue which originated on the lateral aspect. Failure occurred after an average in vivo time of 80.4 months (approximately 6.7 years). Only two of the devices had Rockwell hardness values that were within the ASTM specifications for the alloy. Upon metallurgical examination, moderate to severe levels of gas porosity, interdendritic shrinkage, and nonmetallic inclusions were found in all of the devices. As expected, extremely large grain sizes also were observed in the devices examined. These results indicate that the metallurgical flaws and defects associated with the cast cobalt-chromium-molybdenum alloys used in these devices may preclude successful longterm performance and warrant manufacturer's attention.

Evaluation of hydroxylapatite graft materials in canine cervical spine fusions.

The efficacy of ceramic hydroxylapatite implant materials as graft materials for cervical spine fusion was evaluated in canines. Bioresorbable and non-bioresorbable systems were evaluated at time periods ranging from 1 to 24 weeks. Implant interbody position and progression of fusion were evaluated radiographically and histologically. Implant fracture and extrusion into adjacent soft tissues occurred in nine of 23 cases. Implant fracture occurred in many of the remaining 14 cases, however, the implant materials remained within the interspace. Implant fracture occurred with both implant systems. Radiographically little evidence of fusion was observed at less than 6 weeks, however by 12 weeks evidence of fusion was noted and was confirmed histologically. No difference in fusion rate or degree of fusion was observed between the two implant systems.

A clinical and metallurgical analysis of retrieved Jewett and Richards hip plate devices.

The metallurgical properties of 61 retrieved 316L stainless steel (ASTM F138-76) hip plate devices used for the treatment of intertrochanteric fractures were examined. Surface and screw-plate interface corrosion characteristics were graded, and grain size, inclusion content, and hardness values were measured. These measurements were then correlated with the clinical performance of the devices. The devices studied included 21 Jewett nail-type and 40 Richards compression screw-type hip plates. The devices had been in situ an average of 26.7 months, with in situ periods ranging from 2.0 to 156.0 months. Cause-related reasons represented the majority of removals (89.8%), while only 10.2% of the hip plates were removed on a routine asymptomatic basis. The data suggest that surgeons consider this type of device as a permanent implant, with removal undertaken only for causative factors. Of all devices removed, 30.6% were retrieved from patients who presented with fracture nonunion. Upon microscopic examination, 97% of the retrieved implants exhibited some degree of either surface of interface corrosion. Statistical analysis revealed significant correlations between corrosion scores and the metallurgical properties of grain size and nonmetallic inclusion content. No statistically significant metallurgical or corrosion differences were discerned between the two types of devices studied. However, four implants of the Jewett design and four of the Richards design were found to be out of ASTM specification F-138-76. It should also be noted that four devices of the Jewett design (19%) fractured in situ, while none of the retrieved Richards designs had fractured. No correlation was observed between the plates' corrosion scores and in situ time.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and metallurgical analysis of retrieved internal fixation devices.

The clinical performance, corrosion characteristics, and metallurgical properties of 82 retrieved stainless-steel bone plates have been examined. The plates had been in situ for periods ranging from one to 169 months. Only 29% of these devices (24 of 82 plates) were removed on a routine asymptomatic basis, while 62% (51 of 82 plates) were removed for cause-related reasons such as implant-related pain, infection, nonunion or malunion, and so forth; seven plates were removed for unknown reasons. Although most patients who had plates removed for pain reported some improvement in symptoms, others felt no improvement after removal. On examination, over 89% of the recovered implants displayed some degree of either surface (pitting) or screw-plate interface (crevice and fretting) corrosion or both. Statistical analyses revealed that the metallurgical properties of grain size and nonmetallic inclusion content correlated significantly with the degree of both types of corrosion.

Retrieval and analysis of intramedullary rods. A follow-up study.

From 1980 to 1983, 16 AO intramedullary femoral rods were retrieved and analyzed clinically, radiographically, and metallurgically. Cracking and/or fracture was observed in four of the 16 specimens. All cracks occurred at the point of maximum stress at the end of the slot. In two cases a structurally weaker weld zone coincided with this location. The weld zone and slot were also found to coincide in five of the uncracked rods. Two of the four cracked rods were removed because of pain, while only three of the 12 uncracked rods caused pain. Structural and material characteristics (i.e., the location of the weld at a point of maximum stress and significant variability in microstructure), rather than surgical technique or time in situ, were found to be responsible for the implant mechanical failures. Improvements should be made in fabrication techniques and material properties. For the present, careful assessment of a painful intramedullary rod and routine removal after healing are advisable.

Proprioception in idiopathic scoliosis.

Proprioception testing and gait analysis was performed on a group of 17 patients with idiopathic scoliosis. All curves had documented progression. The average curve was 26.8 degrees, all primary curves being right thoracic. The average age was 14.8 years. Twelve, healthy, age-matched controls underwent identical testing. Results showed that scoliotic subjects had asymmetry in their ability to reproduce angles between their two knees, as well as an absolute deficit in their ability to reproduce angles as compared with controls (P less than 0.01). The threshold of detection of change in angle at the knee was also quantitatively higher than controls (P less than 0.05), although asymmetry was not statistically significant. No significant differences were measured in gait parameters between scoliotics and controls. These joint position tests have been applied previously to young and elderly adults, athletes, and total joint patients. In no group has any asymmetry of response been demonstrated, both extremities showing virtually identical performance in each case. The tests administered measure sensory modalities, which are conducted through the posterior columns. Although the site of damage in the neural pathway cannot be specifically localized by these tests, results of this study support the presence of a neurologic deficit in idiopathic scoliosis.