The inheritance of hip osteoarthritis in Iceland.

OBJECTIVE: To assess, in a population-wide study in Iceland, the genetic contribution to hip osteoarthritis (OA) leading to total hip replacement (THR). METHODS: Information from 2 population-based databases in Iceland was combined: a national registry of all THRs performed between 1972 and 1996, and a genealogy database of all available Icelandic genealogy records for the last 11 centuries. A genetic contribution to THR for OA was assessed by 1) identifying familial clusters of OA patients with THR, 2) applying the minimum founder test (MFT) to estimate the minimum number of ancestors ("founders") that would account for the genealogy of all 2,713 patients with THR for OA, compared with the average number of founders for control lists, 3) calculating an average pairwise kinship coefficient (KC) for the patient list and control lists, and 4) estimating the relative risk (RR) for THR among relatives of OA patients who have undergone the procedure. One thousand matched control lists, each the same size as the patient list, were created using the genealogy database. RESULTS: A large number of familial clusters of patients with THR for OA were identified. The MFT showed that OA patients descended from fewer founders than did subjects in the control groups (P < 0.001). The average pairwise KC among patients with OA was greater than in the control population (P < 0.001). The RR for THR among siblings of OA patients was 3.05 (95% confidence interval 2.52-3.10). CONCLUSION: This population-based study shows that Icelandic patients with hip replacement for OA are significantly more related to each other than are matched controls drawn from the Icelandic population. These findings support a significant genetic contribution to a common form of OA and encourage the search for genes conferring an increased susceptibility to OA.

Instability and femoral head vitality in fractures of the femoral neck.

Sixteen patients with femoral neck fractures were studied with roentgen-stereophotogrammetric analysis (RSA) and low-field magnetic resonance (MR) imaging in addition to plain roentgenography. In six patients, these results were compared with the results of histopathologic analyses. All fractures were stabilized with two cannulated titanium screws. Evaluation of fracture movement before weight bearing (nine fractures) revealed no or only slight movement (less than 3.4 mm or 4.7 degrees). During weight bearing, two undisplaced fractures were compressed about 5 mm and one 20.3 mm, because of delayed union, which was verified by repeated RSA measurements and MR imaging. The average compression in nine displaced fractures that subsequently healed was 13.3 mm. MR imaging revealed signs of femoral head necrosis in three healed and two unhealed fractures. Segmental or total femoral head necrosis was histologically confirmed in all removed femoral heads, and the fracture areas were shown to be bridged by bone trabeculae to a varying degree. Absence of micromovement six months after fracture implied uncomplicated healing. Fracture stabilization at nine to 12 months postfracture was associated with femoral head necrosis or delayed union in four of six cases. Micromotion after more than one year indicated femoral head necrosis or pseudarthrosis.

The accuracy of measurements of femoral neck fractures. Conventional radiography versus roentgen stereophotogrammetric analysis.

Postoperative displacement of the femoral head center was measured in 60 intracapsular hip fractures at repeated conventional radiographic (CR) and roentgen stereophotogrammetric (RSA) examinations. The measurements of the conventional radiographs (405 pairs) were done on a digitizing table. Totally, 105 pairs of these radiographs (AP and lateral, CR) were measured by 2 observers. Manual measurements were also made on 176 pairs of the conventional radiographs. Conventional radiographs tended to overestimate or underestimate the average displacements up to about 2 mm. Two standard deviations of the differences (RSA-CR) varied from 5.8 to 9.6 mm depending on the direction of the movements. The accuracy of the measurements on conventional radiographs did not differ between the 2 examiners. The digitizing table was found to be more accurate than the manual measurements. The accuracy of conventional radiography can most likely be improved by using a strictly standardized examination technique.

Factors influencing postoperative movement in displaced femoral neck fractures: evaluation by conventional radiography and stereoradiography.

Postoperative movement in 46 displaced femoral neck fractures was studied using roentgen stereophotogrammetric analysis (RSA). Thirty-four fractures became stable, all within 1 year. Measurements on pre- and postreduction radiographs and scintimetry were performed to evaluate factors of importance in healing, redisplacement, and nonunion. Thirty-three fractures were treated with two hook-pins with (7 cases) or without (26 cases) a plate, and 13 were treated with two cancellous screws. Presence of intermediate fracture fragments and fixation with two screws implied increased movement of the femoral head center during the postoperative period. Remaining ad latus displacement on the anteroposterior or lateral view after reduction of more than 1 mm and low scintimetric uptake implied increased risk of redisplacement or pseudarthrosis. Increased displacement of the femoral head center during the first postoperative month was recorded in fractures that did not heal. The magnitude of the femoral head rotations did not differ between the implants, but smaller screw axis rotations were noted in fractures that subsequently healed. In most hips fixated with screws, the instant center of femoral head rotation went through the femoral head or neck, whereas hook-pin fixation more commonly was associated with screw axis position within or close to the trochanteric region, suggesting a more durable fixation in the femoral head of this device.

A geriatric-anesthesiologic program to reduce acute confusional states in elderly patients treated for femoral neck fractures.

The aim of this study was to evaluate the effect of a geriatric-anesthesiologic intervention program for the prevention and treatment of acute confusional states (ACS) in elderly patients treated for femoral neck fractures. The intervention program was based on the results of previous prospective studies in similar patient populations. The outcome of the intervention, comprising 103 patients, was compared with that of an earlier study comprising 111 patients. The intervention program consisted of pre- and post-operative geriatric assessments, oxygen therapy, early surgery, prevention and treatment of peri-operative blood pressure falls and treatment of post-operative complications. The incidence of ACS was lower, 47.6%, in the intervention study compared with 61.3% (P less than 0.05) in the control study. Furthermore, the ACS that occurred in the intervention study was less severe and of shorter duration than that in the control study. The incidence of post-operative decubital ulcers, severe falls, and urinary retention was also lower. The mean duration of orthopedic ward stay was 17.4 days in the control study and 11.6 days in the intervention study (P less than 0.001). It can be concluded that the intervention program reduced the incidence, severity, and duration of ACS which resulted in a shortened orthopedic ward stay.

Stability of femoral neck fracture. Roentgen stereophotogrammetry of 29 hook-pinned fractures.

The stability of hook-pin fixation during weight bearing was studied in 29 femoral neck fractures using roentgen stereophotogrammetric analysis. Twenty-three fractures became stable within 1 to 9 months, whereas redisplacement or continuing movement of the fracture occurred in 6 cases. Displaced fractures shortened about 7 mm more than undisplaced ones before healing. The rotations of the femoral heads were greatest in the forward/backward direction, followed by varus-valgus tilting in both fracture groups. Rotation about the longitudinal axis was recorded in the displaced fractures, mainly as a retroversion, whereas no rotation occurred about this axis in the undisplaced fractures. Healing after 6 months, intermediate fracture fragments, and a decreased Pauwels' angle seemed to imply increased fracture compression or rotatory instability. Fractures that subsequently developed healing complications displayed an increased distal displacement of the femoral head during the first postoperative month.

Stability of femoral neck fractures. A postoperative roentgen stereophotogrammetric analysis.

Using roentgen stereophotogrammetric analysis, the postoperative stability of femoral neck fractures was measured in 16 patients. During the first day after internal fixation, before weight bearing, the center of the femoral head moved on an average 1.5 mm (total translation) in six undisplaced fractures and 3.7 mm in 10 displaced fractures, which was about one third of the fracture movement during the first postoperative month. Three undisplaced fractures displayed a rotatory instability, mainly after weight bearing had begun. Five of the displaced fractures showed maximal rotatory displacement during the first postoperative day. The recorded fracture movements before weight bearing may question the rationale of peroperative mechanical compression.

Low field magnetic resonance imaging of femoral neck fractures.

Fourteen patients with cervical hip fractures were treated with internal fixation using titanium screws. The femoral head vitality was evaluated with 99Tcm-MDP scintigraphy and scintimetry within 2 weeks postoperatively and by serial low field magnetic resonance imaging (MR). Two patients with reduced radionuclide uptake (femoral head ratio less than 1.0) developed radiographic signs of femoral head necrosis. MR disclosed the definite area of the necrosis at 2 and 12 months after fracture, respectively. In three of the patients with a high scintimetric uptake (femoral head ratio greater than or equal to 1.0), MR revealed a focal decrease of the signal intensity in the femoral head or neck at 2, 3 and 7 months after fracture, respectively. The radiographs in one of these patients were normal at 7 months after fracture. The second one showed signs of necrosis at 16 months and the last one developed delayed/non-union. With a non-ferromagnetic osteosynthesis the healing course after femoral neck fracture can be studied with low field MR equipment without disturbing artifacts. The time period between ischaemia and definite abnormalities on MR may embrace several months.