Pathogenesis of Alzheimer-related neuritic plaques: AT8 immunoreactive dystrophic neurites precede argyrophilic neurites in plaques of the entorhinal region, hippocampal formation, and amygdala

We examined the reliability of the anteroposterior and posterior condylar axes for determining rotational alignment of the femoral component in total knee arthroplasty (TKA). A computed tomography scan was taken at the level of the femoral epicondyle in 84 knees (27 varus knees with medial femorotibial arthritis (FT-OA) in 26 patients, 17 knees with patellofemoral arthritis in 14 patients, and 40 normal knees in 40 volunteers). On the image, an anteroposterior axis, a line perpendicular to the anteroposterior axis, an epicondylar axis and a posterior condylar axis were drawn, and the relationship between the three axes was assessed. The mean values for the 84 knees were evaluated, and the posterior condylar axis was 6.0 degrees +/- 2.4 degrees internally rotated relative to the epicondylar axis, while the line perpendicular to the anteroposterior axis was 1.4 degrees +/- 3.3 degrees internally rotated relative to the epicondylar axis. The internal rotation angle of the posterior condylar axis relative to the epicondylar axis was 6.2 degrees +/- 1.9 degrees in the knees with medial femorotibial arthritis, 6.4 degrees +/- 2.4 degrees in the knees with patellofemoral arthritis, and 5.8 degrees +/- 2.7 degrees in the normal knees, showing consistent values in normal and osteoarthritic knees. The internal rotation angle of the line perpendicular to the anteroposterior axis relative to the epicondylar axis was 0.1 degrees +/- 3.3 degrees, 1.3 degrees +/- 3. 3 degrees, and 2.3 degrees +/- 3.1 degrees in the three groups, respectively (i.e., there were significant differences between the medial FT-OA knees and the normal knees). The results demonstrated that the anteroposterior axis was rotated externally to a significant degree in medial FT-OA knees and was less reliable than the posterior condylar axis for use in alignment for TKA on medial FT-OA knees.     

Effect of osseous torsions of the lower limb on the development of lateral femorotibial knee arthrosis

PURPOSE OF THE STUDY: Frontal deformation of the knee is certainly not the only factor involved in the occurrence of lateralised tibio-femoral arthrosis. The aim of the study was to analyze if any kind of tibial torsion or femoral torsion could be able to induce lateralized arthrosis. MATERIAL AND METHODS: Femoral torsion, tibial torsion and tibio-femoral index (tibial torsion minus femoral torsion) have been measured on 59 knees with lateral arthrosis (8 knees) or with medial arthrosis (51 knees). For each knee, two frontal deformations were measured: 1) the actual arthrosis deformation was calculated on a hip knee ankle radiograph, 2) the pre arthrosis deformation is the arthrosis deformation minus the angle made by the femoral condyle tangent and the tibial plateau tangent. A knee has no frontal deformation if the angle between the mechanical axis of the femur and the mechanical axis of the tibia is between 178 degrees and 182 degrees; there is a varus deformity if the angle is inferior to 178 degrees; there is a valgus deformation if the angle is superior to 182 degrees. RESULTS: Out of the 8 knees with lateral arthrosis, 2 showed initially no frontal deformation and 6 had a valgus deformation; out of the 51 knees with medial arthrosis, 34 showed initially no frontal deformation, 6 had a valgus deformity and 11 a varus deformity. The tibio-femoral index in lateral FT arthrosis was statistically different from those in medial FT arthrosis (p 0.0001). When a lateral arthrosis appeared whatever the pre arthrosis deformation was the index was always negative (tibial torsion lower than femoral torsion); when a medial FT arthrosis appeared, whatever the pre arthrosis deformation was, the index (except for two cases) was always positive (tibial torsion higher than femoral torsion). CONCLUSION: Femoral and tibial torsions play a part in lateralised arthrosis occurrence together with frontal mechanical factors. Perhaps troubles in torsion explain some spontaneous or post-therapeutic evolutions not explained by frontal mechanical factors.     

The role of the cruciate and posterolateral ligaments in stability of the knee. A biomechanical study

The role of the posterolateral and cruciate ligaments in restraining knee motion was studied in 11 human cadaveric knees. The posterolateral ligaments sectioned included the lateral collateral and arcuate ligaments, the popliteofibular ligament, and the popliteal tendon attachment to the tibia. Combined sectioning of the anterior cruciate and posterolateral ligaments resulted in maximal increases in primary anterior and posterior translations at 30 degrees of knee flexion. Primary varus, primary internal, and coupled external rotation also increased and were maximal at 30 degrees of knee flexion. Combined sectioning of the posterior cruciate and posterolateral ligaments resulted in increased primary posterior translation, primary varus and external rotation, and coupled external rotation at all angles of knee flexion. Examination of the knee at 30 degrees and 90 degrees of knee flexion can discriminate between combined posterior cruciate ligament and posterolateral injury and isolated posterolateral injury. The standard external rotation test performed at 30 degrees of knee flexion may not be routinely reliable for detecting combined anterior cruciate and posterolateral ligament injury. However, measurements of primary anterior-posterior translation, primary varus rotation, and coupled external rotation may be used to detect combined anterior cruciate and posterolateral ligament injury.     

Placental restriction alters adrenal medullary development in the midgestation sheep fetus

This is a retrospective study of 10 patients with combined cruciate ligament and posterolateral instability who underwent surgical reconstruction between 1991 and 1994. All knees had at least 20 degrees increased external rotation at 30 degrees of knee flexion and from 1+ to 3+ varus instability. Five knees with posterior cruciate ligament ruptures had at least a 2+ Lachman test result. (One knee had both anterior and posterior cruciate ligament injuries). In all cases the lateral collateral ligament was reconstructed with a bone-patellar tendon-bone allograft secured with interference screws. Fixation tunnels were placed in the fibular head and at the isometric point on the femur. The cruciate ligaments were reconstructed with autograft or allograft material. The average follow-up was 28 months. Excessive external rotation at 30 degrees of flexion was corrected in all but one knee. Six patients had no varus laxity, and four patients had 1+ varus laxity at 30 degrees of flexion. The posterior drawer test result decreased, on average, to 1+, and the Lachman test result decreased to between 0 and 1+. The average Tegner score was 4.6, with five patients returning to their preinjury level of activity and four returning to one level lower. These results indicate that this is a promising new procedure for patients with instability resulting from lateral ligament injuries of the knee.     

Indications for surgical treatment of tibial condyle fractures

The residual radioanatomic changes influencing the functional, subjective, and clinical outcome of 131 tibial condyle fractures were studied. Clinical function was found to deteriorate rapidly with increasing values of residual medial tilt of the tibial plateau, whereas lateral tilt of the plateau was well tolerated up to 5 degrees. Articular step-off up to 3 mm and condylar widening up to 5 mm had no adverse effects. Seventy percent of knees with moderate or severe instability were functionally unacceptable. It was concluded that a medial unicondylar fracture with any displacement, and all medially tilted bicondylar fractures, should be operated upon. In fracture of the lateral condyle, open reduction and internal fixation is indicated when lateral tilt or valgus malalignment exceeds 5 degrees, articular step-off exceeds 3 mm, or condylar widening exceeds 5 mm. The same limits apply to laterally tilted bicondylar fractures, provided that the medial condyle is undisplaced. Any displacement seen in the axial bicondylar fracture is an indication for surgical treatment. If there is any mediolateral instability in the extended knee joint after rigid internal fixation, repair of a collateral ligament should be considered. An avulsed anterior cruciate ligament should be fixed, if pathologic laxity exists, but the torn ligament can be ignored and reconstructed later if needed.     

The effect of wedged insoles on the thrust of osteoarthritic knees

We describe a method of quantifying the lateral/medial thrust of the knee which occurs in the early phase of walking. We have used this method to evaluate the effects of wedged insoles on the lateral and medial thrust for normal knees and knees with unicompartment osteoarthritis (OA). A laterally elevated (valgus) insole decreased the lateral thrust of both normal and osteoarthritic knees. A medially elevated (varus) insole increased the lateral thrust. In 50 symptomatic knees with medial compartment OA, decreasing the lateral thrust with a valgus insole reduced pain on walking in 27. Patients whose pain was reduced by valgus insoles tended to have earlier OA and to have a significantly greater reduction in the lateral thrust than in the 23 remaining unaffected knees. A varus insole was effective in decreasing the medial thrust and reducing pain in all ten knees with lateral compartment OA. We recommend the use of valgus insoles for patients with painful early medial compartment OA and the use of varus insoles for lateral compartment OA.     

Wear patterns on tibial plateaus from varus and valgus osteoarthritic knees

The size and location of articular cartilage wear was assessed on 106 varus and 37 valgus osteoarthritic tibial plateaus resected during total knee arthroplasty. Anterior cruciate ligament integrity was assessed intraoperatively, and calibrated digital images were used to measure the wear patterns. Complete anterior cruciate ligament deficiency was seen in 25% of the varus and 24% of the valgus knees. Wear patterns on anterior cruciate ligament intact and attenuated varus tibial plateaus occurred in the middle to anterior aspect of the medial plateau. Anterior cruciate ligament deficient varus plateaus had significantly larger wear areas located more posterior on the medial plateau. In contrast, anterior cruciate ligament intact and deficient valgus tibial plateaus had wear located posterior to the center of the lateral plateau. Anterior cruciate ligament integrity is a discrete feature of advanced osteoarthritis that strongly influences the articular wear patterns. The anterior cruciate ligament deficient wear patterns show a wear mechanism that is consistent with the posterior femoral subluxation and posterior tibiofemoral contact observed after acute anterior cruciate ligament rupture. These observations provide insight into the altered knee mechanics that exist in osteoarthritic knees and the resulting mechanical factors that contribute to degenerative changes.     

Meniscal allograft transplantation for unicompartmental arthritis of the knee

Sixty-seven meniscal allografts were transplanted in the knees of 63 patients between 1988 and 1994. Before surgery, all patients experienced refractory disabling knee pain secondary to a prior total meniscectomy with advanced unicompartmental osteoarthritic changes as verified by arthroscopy. At a mean followup of 31 months (range, 1.0-5.5 years), 58 knees (86.6%) attained a good to excellent results-Twenty-one knees received isolated meniscal allografts, with 19 achieving good to excellent results (90.5%). Five knees received a medial or lateral meniscal allograft with an anterior cruciate ligament reconstruction, and 4 (80.0%) obtained good to excellent results. Thirty-four knees received a meniscal allograft in combination with either a valgus high tibial osteotomy, varus high tibial osteotomy, or varus distal femoral osteotomy to correct for preoperative varus or valgus deformities, with 29 (85.3%) attaining good to excellent results. The remaining 7 knees underwent a combined medial meniscal allograft, valgus high tibial osteotomy, and anterior cruciate ligament reconstruction with 6 (85.7%) attaining good to excellent results. The most frequent complication was a traumatic posterior horn tear in 6 knees at a mean of 21 months after surgery (range, 9-43 months), most likely the consequence of unsuccessful healing of the posterior horn of the graft.     

Condylar position with rigid fixation versus wire osteosynthesis of a sagittal split advancement

PURPOSE: In this randomized clinical study, two groups of patients who underwent a bilateral sagittal split osteotomy and either wire osteosynthesis or rigid fixation were compared. PATIENTS AND METHODS: Cephalometric radiographs obtained before surgery, immediately after surgery, and at 8 weeks, 6 months, and 1 and 2 years after surgery were available for 125 of these patients, 63 with wire fixation and 62 with rigid fixation. All were traced by an independent examiner, and vertical and horizontal changes in condylar position were recorded for each period. RESULTS: Condylar movement was slightly different with the two fixation techniques beyond 8 weeks postsurgery, but the ultimate position of the condyle was not different. The condyles in both groups moved posterior and superior. There initially was a correlation between the amount of advancement and the amount the condyle moved inferior in both groups, but this diminished with time. In addition, there was a weak but significant positive relationship between forward rotation of the proximal segment and superior condylar position immediately after surgery, which did not exist at later periods. CONCLUSIONS: Whether wire osteosynthesis or rigid fixation was used, the ultimate condylar position was posterior and superior after a bilateral sagittal split osteotomy to advance the mandible. No single factor could be identified to account for this change. It is suggested that change in mechanical load may have resulted in remodeling and adaptation of the condyles.     

Ranitidine bismuth citrate in the treatment of Helicobacter pylori infection and duodenal ulcer

STATEMENT OF PROBLEM: The existence of mandibular lateral translation and the approaches to its measurement and interpretation by using a pantograph are controversial. PURPOSE: This study evaluated the validity of using a pantograph to measure mandibular lateral translation and analyzed human pantographic tracings to determine whether they exhibited mandibular lateral translation. MATERIAL AND METHODS: A pantograph was modified by adding 2 posterior horizontal recording tables and styli at the transverse horizontal axis. Pantographic tracings of 25 human subjects were compared with the corresponding theoretically determined values for tracings that exhibited only rotation with no translation. Differences in the tracings at 2 pantographic recording table locations, relative to the transverse horizontal axis, were also compared. RESULTS: The character of the lateral component of 100 pantographic tracings all differed from the lateral component of theoretically determined values for pure rotation. In 64% of tracings, over 50% of the total mandibular lateral translation occurred by the first 1 mm of forward movement of the nonworking side condyle. In 94% of tracings, more than 50% of the translation had occurred in the first 3 mm of forward movement. For the pantographic system used, the amount of mandibular translation represented in the tracing was not changed by altering the posterior horizontal recording table position in the anterior-posterior direction, relative to the transverse horizontal axis. CONCLUSION: All subjects showed evidence of mandibular lateral translation. New definitions for timing of mandibular lateral translation are proposed. Of the tracings, 64% were classified as exhibiting early translation, 30% as intermediate, and 4% as late mandibular lateral translation.     

Hematopoietic precursor cell exhaustion is a cause of proliferative defect in primitive hematopoietic stem cells (PHSC) after chemotherapy

The aim of the present study is to determine the possibility of measuring the bone mineral density (BMD) around implants by dual energy X-ray absorptiometry (DEXA). Therefore, the trabecular BMD was measured close to 127-600 microns and at a distance from various uncoated and Ca-P-coated implants inserted into the femoral condyle of goals. The implants were left in situ for 12 weeks. In addition, the bone-implant interface was evaluated histologically. For comparative reasons the BMD of non-implanted lateral and medial femoral condyles was also measured. The reproducibility of the measurements, expressed as a coefficient of variation, was found to be 0.44%. Moreover, the regions closest to the implants exhibited a higher BMD than all other regions, and the regions located in the medial condyle showed a higher BMD than the lateral condylar regions. Although the histological sections of the implants in the medial condyle demonstrated more bone contact with the coated than with the uncoated implants, a higher density was measured around the uncoated implants. The results regarding the non-implanted condyles indicated a higher density in the medial than in the lateral condyle. In view of these results, we conclude that BMD around dental implants depends on the location of the implant and that DEXA appears to be an excellent tool for analysing bone-implant reactions.     

Replacement arthroplasty of the valgus knee. A modified lateral capsular approach with repositioning of vastus lateralis

Total knee arthroplasty (TKR) using a medial capsular approach gives worse results in arthritic knees with valgus deformity than in those in varus, usually because of swelling, poor wound healing and stiffness, instability, recurrent valgus deformity and poor patellar tracking. A technique for replacement TKR of valgus knees using a lateral capsular approach was described several years ago, but was not routinely adopted because of the difficulties with and complexity of the procedure which included deliberate elevation of the tibial tubercle. In order to avoid this we have modified and simplified the procedure. Our preliminary results suggest that this lateral approach is safe and may give a better outcome than that through the medial capsule for the replacement of valgus knees.     

Patellar tracking after total knee arthroplasty. The effect of tibial tray malrotation and articular surface configuration

The effect of total knee arthroplasty (TKA) with neutrally aligned and malrotated tibial trays was studied in five fresh anatomic specimen knees. Patellar shift, tilt, and rotation, and the rotational position of the tibia were measured in normal knees and after TKA with the Ortholoc Modular knee system. Both semiconstrained and unconstrained articular surfaces were assessed in the neutral position and at anatomic, 15 degrees internal, and 15 degrees external rotation of the tibial tray. After TKA, the patellae shifted slightly medially in the early phase of knee flexion because the anterior lateral flange of the femoral component was longer than the lateral trochlea of the femur and because the tibia rotated internally. The raised lateral flange on the femoral component tilted the patella medially at full extension after TKA. The semiconstrained tray allowed minimal tibial rotation because of its articular configuration. As much as 15 degrees malrotation of the unconstrained tibial tray did not affect patellar tracking. The semiconstrained tibial tray in the neutral position had almost the same patellar tracking as the unconstrained tray, but at 15 degrees external rotation, the semiconstrained tray internally rotated the tibia, leading to medial shift of the patella. Although 15 degrees internal rotation caused external rotation of the tibia, the patella did not shift as much laterally, despite the increase in the Q angle.     

Morphological changes of the TMJ condyles of 100 patients treated with the Herbst appliance in the period of puberty to adulthood: a long-term radiographic study

One hundred consecutive patients were treated with the Herbst appliance in the period of puberty to adulthood. The orthopaedic effects on the morphology of the condyles were described from orthopantomographic and transpharyngeal radiographs. The orthopaedic treatment effect was, in most cases, visible as a change in morphology of the condyle, a double contour in the distocranial part of the condyle and sometimes also at the distal surface of the ramus. In patients at the peak of puberty, the double contour was distinct for a short time. In patients in late puberty, the double contour could be seen several months after treatment. At adulthood, males showed, in most cases, double contours, while females showed in most cases nearly unchanged condyles. When double contours were seen, these persisted for a few months to several years after Herbst treatment. The newly formed bone was stable and no TMJ problems were observed. The change in morphology and the double contour of the condyle can be interpreted as bone modelling. The newly formed bone on the posterior part of the condyle can be explained as a response to hypertropic chondrocytes, and that on the posterior part of the ramus as a response of resting osteoblasts to mechanically induced changes in the condyle (adaptive bone growth). In two cases, remodelling resorption was found in the anterior part of the condyle after Herbst treatment, again as a sign of adaptation to changed mechanical influence. In both cases, later refilling with bone was registered during the remodelling process. The biomechanical effect of Herbst treatment on the mandible is also analogous with an impeded matrix rotation combined with relocation of the mandible.     

External rotational positioning of the leg after intertrochanteric combined varus-derotational osteotomy in Perthes' disease

A 13-year-old boy underwent an intertrochanteric combined varus derotational osteotomy (VDO) for Perthes' disease of his right hip. After surgery he walked with his right leg externally rotated. Computed tomography scans of both knees and hips were obtained with the legs in their spontaneous position to evaluate rotation and anteversion. The femoral condyles were in 28 degrees of external rotation on the operated side compared with 2 degrees on the non-operated side. The angle between the femoral neck and the horizontal plane was 32 degrees on both sides. We conclude that there may be a risk that a derotational osteotomy may produce an external rotational position of the leg instead of altering the angle between the femoral neck and the horizontal plane.     

Developing and implementing interprofessional learning in a Faculty of Health Professions

Although medial displacement calcaneal osteotomy has been advocated for treatment of acquired pes planus, no studies have determined the biomechanical consequences at the ankle of such a procedure. The present investigation examined the alteration in ankle motion that resulted from a medial sliding calcaneal osteotomy. In dorsiflexion, the ankle specimens were found to have altered internal rotation and varus alignment. At maximal dorsiflexion, there was a 76% increase in internal rotation (4.4 degrees +/- 2.5 degrees versus 2.5 degrees +/- 1.7 degrees for intact ankles, P < 0.0004) and an increase of 425% in varus (0.42 degrees +/- 0.56 degrees versus 0.08 degrees +/- 0.34 degrees for intact ankles, P < 0.003). There were no significant differences seen in plantar flexion. Based on these results, caution is advised in the indiscriminate use of medial sliding osteotomies, because this procedure may predispose the patient to premature ankle arthritis as a consequence of the altered ankle motions.     

The transepicondylar axis approximates the optimal flexion axis of the knee

The traditional understanding of knee kinematics holds that no single fixed axis of rotation exists in the knee. In contrast, a recent hypothesis suggests that knee kinematics are better described simply as two simultaneous rotations occurring about fixed axes. Knee flexion and extension occurs about an optimal flexion axis fixed in the femur, whereas tibial internal and external rotations occur about a longitudinal rotation axis fixed in the tibia. No other translations or rotations exist. This hypothesis has been tested. Tibiofemoral kinematics were measured for 15 cadaveric knees undergoing a realistic loadbearing activity (simulated squatting). An optimization technique was used to identify the locations of the optimal flexion and longitudinal rotation axes such that simultaneous rotations about them could best represent the measured kinematics. The optimal flexion axis was compared with the transepicondylar axis defined by bony landmarks. The longitudinal rotation axis was found to pass through the medial joint compartment. The optimal flexion axis passed through the centers of the posterior femoral condyles. No significant difference was found between the optimal flexion and transepicondylar axes. To an average accuracy of better than 3.4 mm in translation, and 2.9 degrees in orientation, knee kinematics were represented successfully by simple rotations about the optimal flexion and longitudinal rotation axes. The optimal flexion axis is fixed in the femur and can be considered the true flexion axis of the knee. The transepicondylar axis axis, which is identified easily by palpation, closely approximates the optimal flexion axis.     

A case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach

We report a case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach. A 53-year-old woman had suffered from stiffness and pain in the left occipital region and numbness of the left side of the face for about 2 years before admission. She had also weakness and numbness of the left side of her body for about 2 months before admission, and dysphagia and pain in the occipital region and in the posterior region of the neck produced by straining for about 1 month before admission. Neurological examination revealed left hemiparesis, and hypalgesia and tactile hypesthesia of the left side of the body, including the face. Plain X-P was normal. Enhanced CT scan and gadolinium enhanced MRI revealed a well-enhanced mass attached to the left anterolateral part of the foramen magnum. The left occipital condyle was observed at the lateral side of the attachment part of this mass. Angiography revealed tumor feeders from the meningeal branches of the left vertebral artery and the left ascending pharyngeal artery. Enhanced three-dimensional CT scan clearly showed that the tumor was attached to the left anterolateral part of the foramen magnum, that the left occipital condyle was at the lateral side of the attachment part of this mass and that the jugular foramen and jugular tubercle were situated superolateral to the attachment part of this mass. Considering these factors, we decided that removal of the posterior part of the left occipital condyle was necessary, but removal of the left jugular tubercle was not necessary for a good operative view from the left posterior lateral direction. The tumor was totally removed successfully and good results were obtained by the transcondylar approach without removal of the jugular tubercle. Histology of the tumor revealed meningothelial meningioma. In this case, preoperative evaluation with enhanced three-dimensional CT scan was helpful for deciding the surgical approach. With enhanced three-dimensional CT scan, it is easy to judge whether removal of the posterior part of the occipital condyle and/or the jugular tubercle is necessary for a good operative view, and we can get good images revealing the relationships between the tumor and surrounding structures. Preoperative evaluation with enhanced three-dimensional CT scan is very useful especially in this kind of situation.     

Why do we fail in aging the skull from the sagittal suture?

This study determined the variability of temporomandibular joint (TMJ) disk position in medial, central, and lateral aspects of the joint using magnetic resonance imaging (MRI). Subjects had clinical evidence of reciprocal TMJ clicking (N = 123) or restricted mandibular motion (N = 52). Eighty-nine asymptomatic volunteers provided a control group. Disk position was quantified on MRI by measuring the angle formed by a line through the middle of the condyle and perpendicular to the Frankfort plane and a line through the same midpoint of the condyle and tangential to the posterior-most aspect of the disk. The disk position in asymptomatic TMJs varied considerably with a tendency toward farther anterior placement in more lateral images. In 47 TMJs from a total of 52 TMJ5 (90%), restricted mobility was associated with anterior disk displacement (ADD) without reduction. The disk position demonstrated a mean displacement of 77 degrees without significant differences at the medial and lateral aspects of the condyle. One hundred TMJs from a total of 123 TMJs (81%) with reciprocal clicking demonstrated ADD with reduction. Tomograms revealed larger lateral displacements or rotational displacements in these joints, whereas medial images frequently showed similar ranges of disk positions as compared with asymptomatic TMJs. The results suggest that disk positions of up to +15 degrees on medial tomograms and +30 degrees on lateral tomograms should be regarded as normal variations. Furthermore, multisection analysis of all parasagittal images improved the separation between disk displacement and asymptomatic TMJs.     

Modified Sugioka's osteotomy: more than 130 degrees posterior rotation for osteonecrosis of the femoral head with large lesion

High degree posterior rotational osteotomy was performed on 31 hips with extensive osteonecrosis that were outside of Sugioka's indication. Among them, 18 hips of 13 patients were reviewed at 24 to 94 months (mean, 42 months). The remaining 13 hips were excluded because the followup was less than 2 years. All hips had less than 1/3 of the posterior area intact preoperatively, which is out of the indication for traditional anterior rotational osteotomy. The posterior rotation applied to the femoral head was 130 degrees to 180 degrees (mean, 138 degrees ). Furthermore, 10 degrees to 25 degrees of intentional varus position was added to the rotation (mean, 15.8 degrees). The preoperative intact articular surface of the loaded portion of the femoral head was 0% to 40% (mean, 6.9%) on anteroposterior radiograph, and it was extended postoperatively to a mean of 80.3% (range, 53%-100%). Collapse was prevented in 17 hips that have remained pain free. The remaining 1 hip sustained secondary collapse and joint narrowing. Mean flexion was 105 degrees and abduction was 20 degrees. Postoperative angiography of 9 hips and bony scintigraphy of 17 hips indicated no findings implying impairment of blood supply. Despite a relatively short term experience, it is concluded that this technique was effective in the treatment of large necrotic lesions, especially for young patients.