Patient-specific chondrolabral contact mechanics in patients with acetabular dysplasia following treatment with peri-acetabular osteotomy.

OBJECTIVE: Using a validated, patient-specific finite element (FE) modeling protocol, we evaluated cartilage and labrum (i.e., chondrolabral) mechanics before and after peri-acetabular osteotomy (PAO) to provide insight into the ability of this procedure to improve mechanics in dysplastic hips. DESIGN: Five patients with acetabular dysplasia were recruited in this case-controlled, prospective study. Models, which included anatomy for bone, cartilage, and labrum, were generated from computed tomography (CT) arthrography scans acquired before and after PAO. Cartilage and labrum contact stress and contact area were quantified overall and regionally. Load supported by the labrum, expressed as a percentage of the total hip force, was analyzed. RESULTS: Percent cartilage contact area increased post-operatively overall, medially, and superiorly. Peak acetabular contact stress decreased overall, laterally, anteriorly, and superiorly. Average contact stress decreased overall, laterally, anteriorly, and posteriorly. Only average contact stress on the superior labrum and peak labrum stress overall decreased. Load supported by the labrum did not change significantly. CONCLUSIONS: PAO was efficacious at medializing cartilage contact and reducing cartilage contact stresses, and therefore may minimize deleterious loading to focal cartilage lesions, subchondral cysts, and cartilage delaminations often observed in the lateral acetabulum of dysplastic hips. However, the excessively prominent, hypertrophied labrum of dysplastic hips remains in contact with the femoral head, which continues to load the labrum following PAO. The clinical ramifications of continued labral loading following PAO are not known. However, it is plausible that failure to reduce the load experienced by the labrum could result in end-stage hip OA following PAO.

Patient-specific analysis of cartilage and labrum mechanics in human hips with acetabular dysplasia.

BACKGROUND: Acetabular dysplasia is a major predisposing factor for development of hip osteoarthritis (OA), and may result from alterations to chondrolabral loading. Subject-specific finite element (FE) modeling can be used to evaluate chondrolabral mechanics in the dysplastic hip, thereby providing insight into mechanics that precede OA. OBJECTIVE: To evaluate chondrolabral contact mechanics and congruency in dysplastic hips and normal hips using a validated approach to subject-specific FE modeling. METHODS: FE models of ten subjects with normal acetabula and ten subjects with dysplasia were constructed using a previously validated protocol. Labrum load support, and labrum and acetabular cartilage contact stress and contact area were compared between groups. Local congruency was determined at the articular surface for two simulated activities. RESULTS: The labrum in dysplastic hips supported 2.8-4.0 times more of the load transferred across the joint than in normal hips. Dysplastic hips did not have significantly different congruency in the primary load-bearing regions than normal hips, but were less congruent in some unloaded regions. Normal hips had larger cartilage contact stress than dysplastic hips in the few regions that had significant differences. CONCLUSIONS: The labrum in dysplastic hips has a far more significant role in hip mechanics than it does in normal hips. The dysplastic hip is neither less congruent than the normal hip, nor subjected to elevated cartilage contact stresses. This study supports the concept of an outside-in pathogenesis of OA in dysplastic hips and that the labrum in dysplastic hips should be preserved during surgery.

Computed tomography arthrography with traction in the human hip for three-dimensional reconstruction of cartilage and the acetabular labrum.

AIM: To develop and demonstrate the efficacy of a computed tomography arthrography (CTA) protocol for the hip that enables accurate three-dimensional reconstructions of cartilage and excellent visualization of the acetabular labrum. MATERIALS AND METHODS: Ninety-three subjects were imaged (104 scans); 68 subjects with abnormal anatomy, 11 patients after periacetabular osteotomy surgery, and 25 subjects with normal anatomy. Fifteen to 25 ml of contrast agent diluted with lidocaine was injected using a lateral oblique approach. A Hare traction splint applied traction during CT. The association between traction force and intra-articular joint space was assessed qualitatively under fluoroscopy. Cartilage geometry was reconstructed from the CTA images for 30 subjects; the maximum joint space under traction was measured. RESULTS: Using the Hare traction splint, the intra-articular space and boundaries of cartilage could be clearly delineated throughout the joint; the acetabular labrum was also visible. Dysplastic hips required less traction (∼5 kg) than normal and retroverted hips required (>10 kg) to separate the cartilage. An increase in traction force produced a corresponding widening of the intra-articular joint space. Under traction, the maximum width of the intra-articular joint space during CT ranged from 0.98-6.7 mm (2.46 ± 1.16 mm). CONCLUSIONS: When applied to subjects with normal and abnormal hip anatomy, the CTA protocol presented yields clear delineation of the cartilage and the acetabular labrum. Use of a Hare traction splint provides a simple, cost-effective method to widen the intra-articular joint space during CT, and provides flexibility to vary the traction as required.

Finite element predictions of cartilage contact mechanics in hips with retroverted acetabula.

BACKGROUND: A contributory factor to hip osteoarthritis (OA) is abnormal cartilage mechanics. Acetabular retroversion, a version deformity of the acetabulum, has been postulated to cause OA via decreased posterior contact area and increased posterior contact stress. Although cartilage mechanics cannot be measured directly in vivo to evaluate the causes of OA, they can be predicted using finite element (FE) modeling. OBJECTIVE: The objective of this study was to compare cartilage contact mechanics between hips with normal and retroverted acetabula using subject-specific FE modeling. METHODS: Twenty subjects were recruited and imaged: 10 with normal acetabula and 10 with retroverted acetabula. FE models were constructed using a validated protocol. Walking, stair ascent, stair descent and rising from a chair were simulated. Acetabular cartilage contact stress and contact area were compared between groups. RESULTS: Retroverted acetabula had superomedial cartilage contact patterns, while normal acetabula had widely distributed cartilage contact patterns. In the posterolateral acetabulum, average contact stress and contact area during walking and stair descent were 2.6-7.6 times larger in normal than retroverted acetabula (P ≤ 0.017). Conversely, in the superomedial acetabulum, peak contact stress during walking was 1.2-1.6 times larger in retroverted than normal acetabula (P ≤ 0.044). Further differences varied by region and activity. CONCLUSIONS: This study demonstrated superomedial contact patterns in retroverted acetabula vs widely distributed contact patterns in normal acetabula. Smaller posterolateral contact stress in retroverted acetabula than in normal acetabula suggests that increased posterior contact stress alone may not be the link between retroversion and OA.

Correction of mildly dysplastic hips with periacetabular osteotomy demonstrates promising outcomes, achievement of correction goals, and excellent five-year survivorship.

AIMS: The aim of this study was to compare patient-reported outcome measures (PROMs), radiological measurements, and total hip arthroplasty (THA)-free survival in patients who underwent periacetabular osteotomy (PAO) for mild, moderate, or severe developmental dysplasia of the hip. PATIENTS AND METHODS: We performed a retrospective study involving 336 patients (420 hips) who underwent PAO by a single surgeon at an academic centre. After exclusions, 124 patients (149 hips) were included. The preoperative lateral centre-edge angle (LCEA) was used to classify the severity of dysplasia: 18° to 25° was considered mild (n = 20), 10° to 17° moderate (n = 66), and < 10° severe (n = 63). There was no difference in patient characteristics between the groups (all, p > 0.05). Pre- and postoperative radiological measurements were made. The National Institute of Health's Patient Reported Outcomes Measurement Information System (PROMIS) outcome measures (physical function computerized adaptive test (PF CAT), Global Physical and Mental Health Scores) were collected. Failure was defined as conversion to THA or PF CAT scores < 40, and was assessed with Kaplan-Meier analysis. The mean follow-up was five years (2 to 10) ending in either failure or the latest contact with the patient. RESULTS: There was no significant difference in PROMs for moderate (p = 0.167) or severe (p = 0.708) groups compared with the mild dysplasia group. The numerical pain scores were between 2 and 3 units in all groups at the final follow-up (all, p > 0.05). There was no significant difference (all, p > 0.05) in the proportion of patients achieving target correction for the LCEA between groups. The mean correction was 12° in the mild, 15° in the moderate (p = 0.135), and 23° in the severe group (p < 0.001). Failure-free survival at five years was 100% for mild, 79% for moderate, and 92% for severely dysplastic hips (p = 0.225). CONCLUSION: Although requiring less correction than hips with moderate or severe dysplasia, we found PAO for mild dysplasia to be associated with promising PROMs, consistent with that of the general United States population, and excellent survivorship at five years. Future studies should compare these results with the outcome after arthroscopy of the hip in patients with mild dysplasia. Cite this article: Bone Joint J 2019;101-B(6 Supple B):16-22.

'Bundle busters': who is at risk of exceeding the target payment and can they be optimized?

AIMS: The Bundled Payments for Care Improvement (BPCI) initiative has identified pathways for improving the value of care. However, patient-specific modifiable and non-modifiable risk factors may increase costs beyond the target payment. We sought to identify risk factors for exceeding our institution's target payment, the so-called 'bundle busters'. PATIENTS AND METHODS: Using our data warehouse and Centers for Medicare and Medicaid Services (CMS) data we identified all 412 patients who underwent total joint arthroplasty and qualified for our institution's BPCI model, between July 2015 and May 2017. Episodes where CMS payments exceeded the target payment were considered 'busters' (n = 123). Risk ratios (RRs) were calculated using a modified Poisson regression analysis. RESULTS: An increased risk of exceeding the target payment was significantly associated with increasing age (adjusted RR 1.04, 95% confidence interval (CI) 1.01 to 1.06) and body mass index (adjusted RR 1.03, 95% CI 1.003 to 1.06). Eight comorbid risk factors were also identified (all p < 0.05), only two of which were considered to be potentially modifiable (diabetes with complications and preoperative anaemia). An American Society of Anesthesiologist physical status classification system (ASA) score ≥ 3 (adjusted RR 2.3, 95% CI 1.67 to 3.18) and Charlson Comorbidity Index (CCI) ≥ 3 (adjusted RR 1.94, 95% CI 1.45 to 2.60) were risk factors for bundle busting. CONCLUSION: Non-modifiable preoperative risk factors can increase costs and exceed the target payment. Future bundled payment models should incorporate the stratification of risk. Cite this article: Bone Joint J 2019;101-B(7 Supple C):64-69.

Ten-year survivorship of primary total hip arthroplasty in patients 30 years of age or younger.

Aims: For this retrospective cohort study, patients aged ≤ 30 years (very young) who underwent total hip arthroplasty (THA) were compared with patients aged ≥ 60 years (elderly) to evaluate the rate of revision arthroplasty, implant survival, the indications for revision, the complications, and the patient-reported outcomes. Patients and Methods: We retrospectively reviewed all patients who underwent primary THA between January 2000 and May 2015 from our institutional database. A total of 145 very young and 1359 elderly patients were reviewed. The mean follow-up was 5.3 years (1 to 18). Logistic generalized estimating equations were used to compare characteristics and the revision rate. Survival was evaluated using Kaplan-Meier curves and hazard rates were created using Cox regression. Results: The overall revision rate was 11% (16/145) in the very young and 3.83% (52/1359) in the elderly groups (odds ratio (OR) 2.58, 95% confidence interval (CI) 1.43 to 4.63). After adjusting for the American Society of Anesthesiologists (ASA) score, gender, and a history of previous surgery in a time-to-event model, the risk of revision remained greater in the very young (adjusted hazard ratio (HR) 2.48, 95% CI 1.34 to 4.58). Survival at ten years was 82% (95% CI, 71 to 89) in the very young and 96% (95% CI, 94 to 97) in the elderly group (p < 0.001). The very young had a higher rate of revision for complications related to metal-on-metal (MoM) bearing surfaces (p < 0.001). At last follow-up, the very young group had higher levels of physical function (p = 0.002), lower levels of mental health (p = 0.001), and similar levels of pain (p = 0.670) compared with their elderly counterparts. Conclusion: The overall revision rate was greater in very young THA patients. This was largely explained by the use of MoM bearings. Young patients with non-MoM bearings had high survivorship with similar complication profiles to patients aged ≥ 60 years. Cite this article: Bone Joint J 2018;100-B:867-74.

Subcellular distribution of muscarinic acetylcholine receptors in rat exorbital lacrimal gland.

The muscarinic acetylcholine receptor (MAChR) is an important mediator of parasympathetic regulation of secretion by the rat exorbital lacrimal gland. In order to survey the subcellular distribution of MAChR in lacrimal acinar cells, we have measured the binding of the specific muscarinic cholinergic antagonist [3H]-quinuclidinyl benzilate ([3H]-QNB) to membrane samples isolated from rat exorbital lacrimal glands by differential and equilibrium density gradient centrifugation. Binding of [3H]-QNB in all membrane fractions was consistent with the presence of a single class of receptor which was muscarinic in nature on the basis of its Kd for [3H]-QNB (0.30-0.35 nM) and its ability to interact with the muscarinic agonists carbachol and methachol and the antagonist atropine. MAChR were present at the highest specific activity in acinar cell basal-lateral plasma membrane-derived populations, where Bmax was as high as 1960 fmole/mg protein. However, the density distributions of MAChR and of other membrane markers indicated that the receptors were present also in membranes derived from cytoplasmic structures, where Bmax values ranged from 50.4 to 152.8 fmole/mg protein. Stimulation with 10 microM carbachol for 30 min led to a 20% (P less than 0.05) increase in the relative MAChR content of a population of membranes derived from the acinar cell basal-lateral membrane; an apparent tendency for MAChR activity to decrease in other membrane populations suggests that stimulation might cause a redistribution of MAChR between cytoplasmic pools and the cell surface membranes.

Esterases in acute leukemias: a cytochemical and electrophoretic study.

Specific and nonspecific esterases were extracted from various typical cytologic types of leukemic blasts and subjected to electrophoresis in polyacrylamide gel. Preparations rich in normal granulocytes and normal monocytes were analyzed in a similar manner. The results indicated the presence of specific esterase activity in normal monocytes and in myelomonocytic and histiomonocytic leukemia, and a lack of consistent differences in the electrophoretic patterns of both specific and nonspecific esterases in these leukemias. The results support the viewpoint that distinctions between myelomonocytic and histiomonocytic leukemias cannot be made with certainty, and that they may represent variants within a broad spectrum of monocytic leukemias rather than separate and distinct entities.

Nonspecific esterase activity in pernicious anemia and chronic erythremic myelosis: a cytochemical and electrophoretic study.

Cytochemically, nonspecific esterase activity was detected in megaloblasts from three patients with severe untreated pernicious anemia, in megaloblastoid erythroblasts from five patients with chronic erythremic myelosis (DiGuglielmo syndrome), and in normoblasts from a patient with severe untreated iron-deficiency anemia. Nonspecific esterase activity in all of these erythroblasts was inhibited by sodium fluoride. Enzymatic activity could not be detected in normoblasts from normal marrows. Electrophoretically, three bands of nonspecific esterase activity could be visualized in marrow sonicates from the anemic patients and normal persons. All of these bands were inhibited by sodium fluoride. The results demonstrate that electrophoretically and in terms of fluoride inhibition, nonspecific esterases obtained primarily from erythroid precursors in various types of anemias are similar to nonspecific esterases found in normal marrows presumably containing a more heterogeneous population of cells.

Electrophoretic properties of esterases in chronic granulocytic leukemia.

Granulocytes were obtained from samples of peripheral blood of five patients who had untreated chronic granulocytic leukemia, and polymorphonuclear leukocytes were isolated from peripheral blood of three normal persons. Specific and nonspecific esterases were extracted from leukocyte preparations with cetyltrimethylammonium bromide and with lysolecithin, and subjected to polyacrylamide disk electrophoresis. In samples from both patients and normal persons, electrophoretic patterns of nonspecific esterase activity using alpha-naphthyl acetate and alpha-naphthyl butyrate were similar, and the esterase bands were weakly inhibited by fluoride. Lysolecithin extracts of specific esterase showed similar electrophoretic patterns for patients and normal subjects. However in cetyltrimethylammonium bromide extracts of specific esterase, 11 bands were seen in preparations from all of the patients with chronic granulocytic leukemia. In preparations of normal polymorphonuclear leukocytes, only eight bands were visualized. The results are consistent with an interpretation that these fast-moving components of specific esterase in chronic granulocytic leukemia granulocytes are present in normal polymorphonuclear leukocytes, but in quantities too small to be visualized with the technics used. Alternatively, the apparent "additional" bands of specific esterase may reflect abnormal metabolism of malignant granulocytes in chronic granulocytic leukemia.

Compartment syndrome in the forearm following fractures of the radial head or neck in children.

A volar compartment syndrome of the forearm was identified following a minimally displaced or angulated fracture of the radial head or neck in three children. The fractures were due to a fall from a bed or from a standing height on an outstretched hand. All three patients had symptoms and signs that were consistent with elevated intracompartmental pressure in the forearm when they were first examined, twelve to twenty-four hours after the injury, and all were managed with an emergency fasciotomy of the forearm. The radial fracture was treated without reduction in the first patient, with manipulative closed reduction in the second patient, and with open reduction and stabilization with Kirschner wires in the third patient. All three patients had a full functional recovery.

The fate of well fixed cemented femoral components left in place at the time of revision of the acetabular component.

The results were reviewed for thirty-seven hips (thirty-five patients) in which a well fixed femoral component that originally had been implanted with use of a so-called first-generation cementing technique was subsequently left in place at the time of revision of the acetabular component without cement. The purpose of the study was to determine the rate of survival of the femoral component and the complications associated with revision of one side of the joint. The femoral components had been in situ for a mean duration of 102 months (range, twelve to 216 months) at the time of the revision of the acetabular component. At the time of follow-up after the revision of the acetabular component, one patient (one femoral component; 3 per cent) had died, twenty-seven femoral components (73 per cent) were in place and radiographically stable, one femoral component had been removed because of infection, six (16 per cent) had been revised because of aseptic loosening, and two (5 per cent) were definitely loose according to radiographic criteria. Excluding the failures and death, the mean duration of follow-up was sixty-five months (range, forty-eight to 121 months). The predicted survival of the femoral component after the revision of the acetabular component was 88 per cent (95 per cent confidence interval, 82 to 94 per cent) at forty-eight months and 78 per cent (95 per cent confidence interval, 67 to 89 per cent) at eighty-eight months. Dislocation occurred in three hips (8 per cent), and a trochanteric non-union occurred in five (14 per cent). The mean rate of linear polyethylene wear did not differ significantly (0.13 as compared with 0.12 millimeter per year; p = 0.74) from that for a comparable group of forty-nine hips that had had a revision of the femoral component without cement and had been followed for a similar duration. The data support the decision to retain a well fixed femoral component that has been implanted with a so-called first-generation cementing technique when the acetabular component subsequently needs a revision. The survival of the femoral component and the risk of associated complications do not appear to be appreciably altered by revision of the other side of the joint.

Revision total hip arthroplasty without cement: subsidence of proximally porous-coated femoral components.

We prospectively studied the intermediate-term results of forty-nine revision total hip arthroplasties without cement that were performed because of aseptic loosening of a cemented femoral component in forty-five consecutive patients; the mean duration of follow-up was sixty-five months (range, forty-five to eighty-seven months). A curved, long-stem, titanium-alloy, non-circumferentially porous-coated femoral component was implanted in each hip. Preoperatively, a staging system was used to classify deficiencies of femoral bone stock according to the loss of cancellous or cortical bone in the metaphysis and diaphysis. Forty-one hips (84 per cent) had cortical or ectatic cavitary bone loss in the metaphysis. The mean Harris hip score significantly improved from 54 points preoperatively to 84 points at the time of the latest follow-up examination (p < 0.001). Twenty-seven patients (twenty-eight hips; 57 per cent) had at least two millimeters of subsidence of the femoral component during the first postoperative year. Eight patients (eight hips; 16 per cent) had no further progression of subsidence. Twenty-one patients (twenty-two hips; 45 per cent) had at least two millimeters of subsidence on two separate postoperative evaluations and therefore were considered to have progressive subsidence. Seventeen patients (nineteen hips; 39 per cent) had no measurable subsidence and were considered to have a stable femoral component. One of these seventeen patients had had a bilateral femoral revision and had progressive subsidence on one side. There was a positive trend for an association between subsidence and the degree of preoperative femoral bone deficiency (p = 0.10), but there was no association between subsidence and the fit of the prosthesis in the metaphysis and diaphysis or the fill of the canal of the femur (p > 0.50). There was no significant loss of bone in the hips with either a stable or a subsided femoral component (p > 0.50), and qualitative reconstitution of the cortex was noted in eleven (52 per cent) of the twenty-one most severely deficient (stage-III) femora. Survivorship analysis showed that, at seventy-two months, there was a 96 per cent chance of survival of the component (95 per cent confidence limits, 0.89 to 1.0) with revision as the end point but only a 37 per cent chance of survival (95 per cent confidence limits, 0.15 to 0.59) with revision or progressive subsidence as the end point.(ABSTRACT TRUNCATED AT 400 WORDS)

The bone-implant interface of femoral stems with non-circumferential porous coating.

UNLABELLED: A histological study was performed of the bone-implant interface of fifteen titanium-alloy femoral stems with porous coating limited to three proximal areas that did not cover the full circumference of the device. The specimens were obtained at autopsy from ten cadavera at a mean of forty-six months (range, one to eighty-nine months) after the implant had been inserted without acrylic cement. The volume fraction of bone within the porous spaces (the percentage of the porous space that was filled with bone) and the extent of bone ingrowth (the percentage of the porous-coated surface covered with in-grown bone that was more than one-half fiber-diameter deep, as measured from the outer surface of the porous coating), were determined with histomorphometric methods. Eleven of the fifteen stems had bone within the porous coating that was in continuity with the surrounding medullary bone. The mean volume fraction of bone ingrowth in these specimens was 26.9 per cent (range, 12.2 to 61.0 per cent), and the mean extent of bone ingrowth was 64.3 per cent (range, 28.6 to 95.2 per cent). Both of these parameters increased with time. In the other four stems, the bone lacked continuity with the surrounding trabecular bed. Two of these stems had a limited amount of bone within the porous coating, and two stems (from one patient) had no bone ingrowth. Periprosthetic membranes surrounded by a shell of trabecular bone covered the uncoated surfaces of the stems. The membranes of implants that had been in situ for eight months or more demonstrated polyethylene wear debris, and other particles generated at the level of the joint, within histiocytes throughout the length of the femoral stem. CLINICAL RELEVANCE: The findings in this study are relevant to the utilization and mechanisms of failure of femoral stems inserted without cement. Bone ingrowth and the resulting stability of the implant can be achieved with porous-coated stems. However, the extent of the surface that is porous-coated must be sufficient to prevent trabecular fracture as a secondary mechanism of loosening. Interruptions in the circumferential extent of the porous surface are associated with the formation of periprosthetic membranes, which provide a pathway for migration of particulate wear and corrosion products to the distal part of the stem. A circumferential coating may retard the access of particles and thus decrease the possibility of diaphyseal osteolysis.

Closed reduction and percutaneous pinning of displaced supracondylar humerus fractures in children: description of a new closed reduction technique for fractures with brachialis muscle entrapment.

A retrospective review of 43 displaced extension-type supracondylar humerus fractures in children was performed. Thirty-four fractures were completely displaced (type III). Ninety-one percent (39 of 43) of the fractures were managed by immediate closed reduction and percutaneous pinning. Ten type III fractures exhibited clinical or radiographic evidence of brachialis muscle penetration. A closed reduction maneuver designed to "milk" the entrapped brachialis muscle off of the proximal fracture spike was developed and was successful in all eight cases in which it was attempted. At mean follow-up of 35 months, 97% (38 of 39 patients) achieved a good or excellent result based on the Flynn grading scale.

Type II floating knee: ipsilateral femoral and tibial fractures with intraarticular extension into the knee joint.

Thirty-four patients with ipsilateral fractures of the femur and tibia with intraarticular extension into the knee of at least one fracture were reviewed at an average follow-up of 38 months. Joint involvement was present in 22 (65%) femoral fractures and 23 (68%) tibial fractures. In 11 (32%) patients, both fractures were intraarticular. In 71% of the patients, there were major associated injuries. Open fractures were common, occurring in 21 (62%) extremities. Associated vascular injuries were seen in seven (21%) cases. Ninety percent of the fractures were surgically stabilized. The average time to healing was 39 and 37.5 weeks for the femur and tibia, respectively. The average flexion of the knee was 96 degrees (5-140 degrees) with flexion contractures occurring in five (15%) knees. Results were graded according to criteria established by Karlström and Olerud. Only eight (24%) patients had good or excellent results. Complications were frequent, with deep infections occurring in 11 (32%) extremities, leading to above-knee amputations in three (9%) patients. This subgroup of floating knee injuries appears to be associated with a higher degree of systemic trauma, a higher percentage of open injuries, and a much graver prognosis.

A biomechanical analysis of internal fixation of complex tibial plateau fractures.

OBJECTIVE: To compare the mechanical stability of fixation of an unstable bicondylar tibial plateau fracture with several different fixation techniques in a cadaveric model. DESIGN: Randomized laboratory investigation using a simulated bicondylar tibial plateau fracture with metaphyseal-diaphyseal dissociation. SETTING: Complex tibial plateau fractures were instrumented and tested under ramp and cyclic loading conditions on a servohydraulic materials testing machine. INTERVENTION: Each tibia was instrumented sequentially with a lateral buttress plate, a lateral and a medial buttress plate, and a lateral buttress and an anteromedial antiglide plate for ramp load testing. For cyclic testing, one of the three constructs was used on each specimen. MAIN OUTCOME MEASUREMENTS: Vertical subsidence of the medial tibial plateau was measured in both ramp and cyclic loading in order to evaluate the three internal fixation techniques. RESULTS: No significant difference was measurable between the dual buttress construct and the lateral buttress/anteromedial antiglide construct. However, the lateral buttress plate alone provided significantly less stability. CONCLUSIONS: A lateral buttress plate with an anteromedial antiglide plate may provide equally effective fixation as compared with the dual buttress plating technique in complex tibial plateau fractures. This less invasive technique may also be associated with fewer complications due to the lack of soft tissue stripping that is required for its application.

Hip pain in the young adult: diagnosis and treatment of disorders of the acetabular labrum and acetabular dysplasia.

Hip pain in the young adult patient (ages, 17-35 years) is a diagnostic and therapeutic challenge for the orthopedic surgeon. The diagnostic and treatment algorithm for many causes of hip pain in the young adult-such as tumors and tumoral conditions, rheumatoid and degenerative arthritis, osseous necrosis, and the sequelae of congenital problems such as slipped capital femoral epiphysis and Legg-Calve Perthes--are well described and established. However, the diagnosis and treatment algorithm for disease processes, such as disorders of the acetabular labrum and dysplasia of the hip, are less clear. Advances in diagnostic radiology, particularly magnetic resonance arthrography, and advances in therapy, including the successful use of the Bernese periacetabular osteotomy and hip arthroscopy, have allowed for both timely diagnosis and appropriate treatment of these sources of hip pain in the young adult. The purpose of this review is to outline the diagnostic and treatment decision-making protocol for young adult patients with hip pain, and specifically to discuss the treatment of acetabular labral tears and dysplasia of the hip.

Triple innominate osteotomy in young adults for the treatment of acetabular dysplasia: a 9-year follow-up study.

Fifty patients who underwent 60 triple innominate osteotomies were reviewed radiographically and clinically using a modified Harris hip score (HHS). Average patient age was 26 years (range: 13-48 years). At average 9-year follow-up (range: 5-14 years), 12 (20%) hips had been converted to total hip arthroplasty (THA) and 4 (7%) hips had incapacitating pain. Sixteen (27%) hips were considered failures. Average modified HHS at final follow-up was 67 (range: 28-91). Forty-nine (98%) of 50 patients reported they would recommend the procedure to others in the same situation. Radiographically, there was significant improvement in the center-to-edge angle of Wiberg and the acetabular angle of Sharp. There also was a statistically significant relationship between failure of the osteotomy and severity of preexisting hip arthrosis as measured by the Tonnis criteria. The results demonstrate triple innominate osteotomy was effective in eliminating pain, but the fact that 27% of hips required or will require THA indicates results may deteriorate with time.