In-hospital grouping rehabilitation of hybrid closed-wedge high tibial osteotomy results in shorter hospital stays and better clinical outcomes.

[Purpose] This study aimed to examine the impact of physiotherapy on various patients who underwent hybrid closed-wedge high tibial osteotomy. [Participants and Methods] Eighty-four patients were divided into three groups: non-weight-bearing, enhanced recovery after surgery, and grouping exercise. The number of hospital days, distinctions in the duration of cane-walking independence, and postoperative complications were compared among the three groups. Furthermore, the Japanese Orthopaedic Association score and physical function were assessed preoperatively and at 3 and 12 months postoperatively. [Results] There were no considerable differences in postoperative complications among the three groups, and the mean hospital stay was the shortest for the grouping exercise group. At 3 months postoperatively, the grouping exercise group reported less walking pain than the enhanced recovery after surgery group. At 3 and 12 months postoperatively, the grouping exercise group showed greater mean knee extensor strength and a higher mean Japanese Orthopaedic Association score than the non-weight-bearing group. [Conclusion] Grouping exercise therapy, in addition to enhanced recovery after surgery protocol, results in shorter hospital stays, no difference in postoperative complications, and good clinical outcomes.

Association between clinical symptoms and lateral thrust 12 months after high tibial osteotomy.

[Purpose] This study aimed to assess the correlation between lateral thrust and clinical symptoms after high tibial osteotomy and determine lower limb alignments that may decrease lateral thrust. [Participants and Methods] We included 54 patients (73 knees) who underwent high tibial osteotomy. Clinical symptoms, including the Japanese Orthopaedic Association score and the hip-knee-ankle angle measured via radiography, were assessed 12 months postoperatively. Lateral thrust was measured using three-dimensional motion analyses. Logistic regression was used to calculate the cut-off values with good Japanese Orthopaedic Association score and lateral thrust as dependent variables and both lateral thrust and hip-knee-ankle angle as independent variables. [Results] The lateral thrust cut-off was 3.1° (sensitivity: 0.83; specificity: 0.74; area under the curve: 0.76), while that of the hip-knee-ankle angle was 1.9° of valgus (sensitivity: 0.71; specificity: 0.81; area under the curve: 0.72). [Conclusion] Good clinical outcomes after high tibial osteotomy can be expected with a lateral thrust of ≤3.0°, indicating that the target hip-knee-ankle angle should be 2.0° valgus. In cases where valgus alignment is insufficient, lateral thrust may develop, which should be assessed using gait analysis.

Association of clinical symptoms and metabolic syndrome-related factors in patients undergoing high tibial osteotomy.

[Purpose] This study aimed to investigate the relationship between clinical outcomes after high tibial osteotomy and metabolic syndrome-related factors, such as hypertension, dyslipidemia, diabetes mellitus, and obesity. [Participants and Methods] A total of 73 patients (73 knees) who underwent high tibial osteotomy for knee osteoarthritis between 2018 and 2020 were included. We investigated the correlation between metabolic syndrome-related factors and clinical symptom assessment (Japanese Orthopedic Association Score) and examined knee function and lower alignment. [Results] At three months postoperatively, the Japanese Orthopedic Association score showed no main and synergistic effects on metabolic syndrome-related factors, and the preoperative Japanese Orthopedic Association score only showed a main effect on metabolic syndrome-related factors. At 12 months postoperatively, the Japanese Orthopedic Association score showed main and synergistic effects on diabetes mellitus, obesity, hypertension and dislipidemia. [Conclusion] Metabolic syndrome-related factors are associated with poorer clinical outcomes after high tibial osteotomy.

Femoral-varus tibial-valgus osteotomy (FVTVO) for neutrally-aligned knee osteoarthritis with severe joint line obliquity enables return to sports activities: A case series study.

Background: Re-alignment surgeries for uni-compartmental knee osteoarthritis, such as high tibial osteotomy (HTO) for varus knees or distal femoral osteotomy (DFO) for valgus knees, are recognized as standard strategies. However, the treatment strategy has not been established for patients with a neutrally-aligned osteoarthritic knee with severe joint line obliquity (JLO) owing to the combination of a valgus femur and a varus tibia; i.e., type II coronal plane alignment of the knee (CPAK). total knee arthroplasty (TKA) can be an option for CPAK type II-aligned osteoarthritis in older inactive patients. Here, we hypothesized that joint line horizontalization by femoral-varus tibial-valgus osteotomy (FVTVO), which may reduce the shear stress induced by JLO, could be a treatment option for CPAK type II-aligned osteoarthritis in young active patients who wish to return to sports (RTS) activity. Our aim in this study was to evaluate the postoperative results of FVTVO with RTS. Methods: Our indications for FVTVO are as follows: JLO >5°; mechanical medial proximal tibial angle (mMPTA) < 87°; mechanical lateral distal femoral angle (mLDFA) < 87°; typical osteoarthritis patterns for CPAK type II on magnetic resonance images, namely osteoarthritic change of the lateral tibial spine, medial slip of the femur, and/or lateral meniscal extrusion from the lateral femoral condyle; and flexion contracture <10°. We enrolled patients who wished to RTS and who had a pre-symptom Tegner score ≥5 and had completed at least a 1-year follow-up. For FVTVO, closed-wedge DFO was performed in all femurs; both closed-wedge HTO and open-wedge HTO were used in the tibia, depending on the situation. Range of motion exercises began on the first postoperative day, and full weight-bearing was permitted 6 weeks postoperatively. Jogging was permitted 3 months postoperatively after confirming bone union, and patients could gradually return to their sports activity 6-12 months' postoperatively. The Japanese Orthopaedic Association (JOA) score and knee flexion range were assessed preoperatively and at the last follow-up. Tegner activity scale scores were assessed presymptom, preoperatively, and at the last follow-up. The hip-knee-ankle (HKA) angle, JLO, mMPTA, and mLDFA were evaluated radiologically, and meniscal extrusions, osteoarthritic change, and/or bone marrow edema were assessed on magnetic resonance images. Results: One man and two women were included in this case series. Two were competitive athletes and one was a mountain climber. The patients' ages were 69, 46, and 57 years (Case 1, 2, and 3, respectively). All patients' CPAK type was converted from type II to type V; i.e., neutral-aligned knee with a neutral joint line, postoperatively. All patients returned to their presymptom sports activity level by the final follow-up. The presymptom/preoperative/final follow-up Tegner scale in Case 1, 2, and 3 were 6/1/6, 5/2/5, and 7/3/7, respectively. Conclusion: Joint line horizontalization by FVTVO for patients with a neutral-aligned knee with severe JLO provided highly satisfactory clinical results and successfully led to RTS.

Risk factors that hinder locomotive syndrome improvement following surgery for musculoskeletal diseases in older patients: A multicentre prospective study.

OBJECTIVES: This study aimed to evaluate preoperative and post-operative locomotive syndrome (LS) in older adults undergoing surgical treatment for musculoskeletal diseases of the lumbar spine and lower extremities and identify risk factors that impede LS improvement after surgery. METHODS: The baseline evaluation included 471 patients 65 years or older [276 in the pre-old-age (65-74 years) group; 195 in the old-age (75 years or older) group] and examined the preoperative and post-operative LS data. The second evaluation performed to identify risk factors, including anthropometric measurements, comorbidity, and frailty, that hinder LS improvement after surgery included 378 patients with preoperative LS Stage 3. RESULTS: Preoperatively, 80% of the patients had LS Stage 3; this rate decreased to 40% post-operatively. Half of the patients exhibited post-operative LS improvement. The LS improvement rate was higher in the pre-old-age group than in the old-age group. According to the multiple logistic regression analysis, old age, high body mass index, weak hand grip strength, and high 5-factor modified frailty index score were significant risk factors that hinder LS improvement after surgery. CONCLUSIONS: Ageing, obesity, weak muscle strength, and frailty can hinder LS improvement in older patients who undergo surgery.

Anteromedial plating without filling the gap in open wedge high tibial osteotomy may increase the risk of screw breakage, which can be reduced by medial plating and bone-substitute insertion.

BACKGROUND: Open wedge high tibial osteotomy (OWHTO) brings new complications such as screw breakages with or without correction loss and time-dependent increased posterior tibial slopes (PTS) due to the opening gap. For preventive purposes, we changed our OWHTO procedure from anteromedial plating without filling the gap (non-grafted group, n = 40, 2009-2012) to medial plating with bone-substitute insertion (grafted group, n = 45, 2012-2015). The objectives of this study were to evaluate the complication patterns and the effects of the modifications. METHODS: Patients undergoing OWHTO with TomoFix plates were included in this retrospective study. Demographics, clinical outcomes (flexion range and Japanese Orthopaedic Association score) and radiological outcomes (femorotibial angle) were assessed in both groups pre-operatively and 2-years postoperatively. The plate installation angle [PIA] and screw insertion depth [SID] were measured on computed tomographic slices at 6 months. PIA/SID was defined as the angle between the tibial anteroposterior axis and plate-width axis/the distance between the proximal screw tip and the proximal tibiofibular joint. The non-grafted group was further divided into complication and non-complication subgroups. Screw breakages were assessed during plate removal (1.5-2.5 years postoperatively). RESULTS: There were no differences in baseline characteristics or radiological/clinical outcomes between the non-grafted and grafted groups. There were 0 and 11 complications in the grafted and non-grafted groups, respectively. Complications included 7 screw breakages, 4 correction losses, and 5 time-dependent increased PTS with some overlaps. PIA and SID were significantly lower (p < 0.001) and higher (p < 0.001), respectively, in the grafted group and significantly lower (p = 0.018) and higher (p = 0.040), respectively, in the non-complication subgroup within the non-grafted group. The cutoff value of PIA for complications was calculated at 48.0°. CONCLUSIONS: Medial plating OWHTO (PIA<48°) using bone-substitute with deeper screw insertion reinforces the opening gap for better angular stability compared with anteromedial plating without bone-substitute.

Around-knee osteotomy conversion for failed high tibial osteotomy: Re-correction high tibial osteotomy and additional distal femoral osteotomy may enable return to sporting activities.

High tibial osteotomy (HTO) for knee osteoarthritis achieves excellent short- and long-term results. However, failure of HTO due to undercorrection or correction loss may necessitate conversion surgery. For patients with HTO failure who desire a return to sporting activities (RTS), non-prosthetic joint-preserving solutions such as conversion to around-knee osteotomies (AKO-conversion) may be more appropriate than total knee arthroplasty. The present study aimed to introduce potential non-prosthetic joint-preserving solutions for failed HTO and investigate the postoperative RTS. Among the patients who received non-prosthetic solutions for failed HTO from 2015 to 2020, this case series included those who were eager to RTS, were participating in a sporting activity with a Tegner activity scale score of ≥5 immediately before being affected by knee osteoarthritis, and had at least 2 years of follow-up. Deformity analysis for the preoperative planning of the AKO-conversion was based on the mechanical lateral distal femoral angle, joint line convergence angle, and mechanical medial proximal tibial angle. Four patients met the study inclusion criteria: two patients who underwent re-correction HTO and two who received additional distal femoral osteotomy (DFO). The average ages at primary HTO and AKO-conversion were 69.5 ± 11.8 years and 71.5 ± 10.9 years, respectively. The hip-knee-ankle angle was corrected from -2.8 ± 1.5° before conversion surgery to 3.3 ± 1.5° at 2 years after AKO-conversion. All four patients finally achieved a better sporting performance after AKO-conversion than preoperatively, and the Tegner activity scale score was improved from 2.5 ± 1.0 before AKO-conversion to 5.8 ± 0.5 at the 2-year follow-up. The duration between AKO-conversion and full RTS was 11.8 ± 6.7 months. In conclusion, two patients who underwent re-correction HTO and two who underwent additional DFO for undercorrection or correction loss after primary HTO achieved highly satisfactory clinical results, including RTS. The present findings suggest that non-prosthetic joint-preserving solutions using AKO for failed HTO should be considered as options to enable RTS.

Open Wedge High Tibial Osteotomy with Pes Anserinus Preservation and Insertion of Bone Substitutes.

Biplanar open wedge high tibial osteotomy (OWHTO) has become common since the introduction of OWHTO-specific plates. However, the management of soft tissues, including skin, the pes anserinus, and the superficial medial collateral ligament (sMCL) release vary among surgeons. We introduce an OWHTO methodology that avoids pes incision and repair, uses bone substitute insertion into the opening gap and includes management of soft tissues to minimize complications. We adopted a reversed curved oblique incision to reduce the risk of saphenous nerve injury. We avoided pes incision, taking advantage of its posterior component force to allow it to function as a compressor of the ascending osteotomy site. The proximal component force of the pes provides compression between the bone substitute insertions and the proximal/distal cortices. This allows postoperative weight bearing to be distributed to the substitute, which may reduce the risk of implant failure. The sMCL is detached from the distal tibial attachment without cutting, enabling its return to its original position underneath the pes and to be repaired. This sMCL release with complete pes preservation may reduce the risk of deep infection or medial laxity during total knee arthroplasty conversion, and further reduce the risks of OWHTO.

Evaluation of locomotive syndrome in patients receiving surgical treatment for degenerative musculoskeletal diseases: A multicentre prospective study using the new criteria.

OBJECTIVES: This study aimed to evaluate the condition of patients with locomotive syndrome (LS) and their improvement after undergoing surgery for degenerative musculoskeletal diseases using the new criteria, including stage 3. METHODS: In total, 435 patients aged ≥40 years (167 middle-aged and 268 older) were divided into four groups based on the disease location: the lumbar (n = 118), hip (n = 191), knee (n = 80), and foot and ankle (n = 46) groups. Patients were evaluated by pre- and 1 year postoperative LS risk tests, including the stand-up test, two-step test, and 25-Question Geriatric Locomotive Function Scale. RESULTS: The pre- and postoperative prevalence of LS stage 3 were 78% and 29%, respectively. The postoperative LS stage improved in 62% of patients (77% and 53% in the middle-aged and older groups, respectively). Overall, the knee group showed the worst results, and the foot and ankle groups showed the best pre- and postoperative results. The pre- and postoperative prevalence of LS stage 3 according to the 25-Question Geriatric Locomotive Function Scale were comparable to those based on the total assessment. CONCLUSIONS: The new LS stage criteria are appropriate, and the 25-Question Geriatric Locomotive Function Scale is a good option for evaluating patients requiring surgery.

High tibial osteotomy solely for the purpose of return to lifelong sporting activities among elderly patients: A case series study.

Knee osteoarthritis (KOA) is a common joint disease among older individuals, associated with increased mortality rates. The current study was conducted to examine whether open wedge high tibial osteotomy (OWHTO) is an effective treatment for elderly patients with a desire to return to sporting activities (RTS) who do not report inconvenience or pain in activities of daily living. We examined a case series of 9 KOA patients (12 knees) aged 50 or above with a desire for RTS, who underwent HTO. We assessed patients before surgery and 2 years after surgery to evaluate surgical outcomes and RTS. The results revealed that patients' average Japanese Orthopaedic Association score was significantly improved at 2 years after surgery (97.5 ±â€¯4.5), compared with the preoperative score (87.9 ±â€¯7.2; p = 0.008). In addition, the average Tegner activity level score was significantly improved at 2-year follow-up (5.8 ±â€¯1.1) compared with the preoperative score (2.8 ±â€¯1.1; p < 0.001). Eight of nine cases except a marathon runner returned to pre-symptom sporting performance levels. Overall, the current findings suggest that OWHTO provides an appropriate treatment for older KOA patients with a desire for RTS.

Suture Anchor Repair for a Medial Meniscus Posterior Root Tear Combined With Arthroscopic Meniscal Centralization and Open Wedge High Tibial Osteotomy.

Medial meniscus posterior root tear (MMPRT) is now attracting increased attention as a risk factor for the development of osteoarthritis. However, the healing rate after root repair by the suture anchor technique or the pull-out technique is still low. Here we report on a technique of MMPRT repair using suture anchor combined with arthroscopic meniscal centralization and open wedge high tibial osteotomy (OWHTO). The purposes of this technique are (1) to distribute the meniscal hoop tension between the root repair site and the centralization site and (2) to reduce the load on medial meniscus by OWHTO. The routine exposure for OWHTO with superficial medial collateral ligament release creates good visualization for arthroscopic root repair. The first anchor is inserted on the medial edge of the medial tibial plateau, and the second anchor is inserted on the root attachment through a posteromedial portal. After tying the knots, OWHTO could be performed without interference between the suture anchors and the screws of the plate for fixing the osteotomy. Although further follow-up is required, this technique could improve the outcomes after root repair, as well as have some technical advantages.

Additional distal femoral osteotomy for insufficient correction after high tibial osteotomy.

A 70-year-old man who was treated with a closed-wedge high tibial osteotomy (HTO) had recurrent right medial knee pain 12 years after the initial osteotomy. We planned a recorrection osteotomy because the patient led an active lifestyle, had well-preserved range of motion and the lateral compartment was still intact. According to preoperative deformity analysis, which indicated a tibia in slight valgus and a femur in moderate varus, recorrection of the distal femur was chosen. Seven degrees of biplanar distal femoral osteotomy (DFO) was performed using a contralateral version of the TomoFix Medial Distal Femur. At 1 year follow-up, the femorotibial angle had improved from 178° to 170°, and the Japanese Orthopaedic Association score had improved from 75 to 95 points. Additional DFO could be a viable alternative for total knee arthroplasty or recorrection HTO when the centre of the deformity is located at the distal femur.

Association between the severity of symptomatic knee osteoarthritis and cumulative metabolic factors.

BACKGROUND: The association between cumulative metabolic syndrome (MS) factors and knee osteoarthritis (KOA) has been highlighted over the past two decades. AIMS: To clarify the relationship between cumulative MS factors and symptomatic KOA. METHODS: A cross-sectional survey involving 119 women aged 45-88 years who were scheduled to undergo knee surgery was conducted. They were stratified into tertiles of symptoms as assessed by the Japanese Orthopedic Association score for KOA. Multinomial logistic regressions were performed using the severity of symptomatic KOA as the dependent variable and each MS factor or the cumulative MS factors as the independent variables. RESULTS: Logistic regression analyses were performed with the upper tertile of stratified symptoms of subjects used as the reference group. After adjustment for confounders, KOA patients who had two (p = 0.004) or three or more (p < 0.0001) MS factors were significantly more likely to have severe symptoms compared to those who had no MS factors. MS factors excluding obesity were similarly analyzed. Even after additional adjustment for body mass index (BMI), KOA patients who had two or more (p = 0.005) MS factors were significantly more likely to have severe symptoms. CONCLUSION: Among KOA female patients diagnosed using radiographic definition, the severity of symptomatic KOA was significantly associated with hypertension, dyslipidemia, and the number of MS factors after adjustment for age, BMI, strength of the knee extensor, and Kellgren-Lawrence grade. The severity of radiographic KOA was not associated with any MS factor or cumulative MS factors.

Closed Wedge Distal Femoral Osteotomy with a Polyaxial Locking Plate Designed for the Proximal Tibia: Minimum 5-Year Outcomes.

Since distal femoral varus osteotomy (DFO) -specific plates had not been available in Japan before 2015, we performed DFO using a plate for tibia. The purpose of this study was to elucidate the efficacy and problems associated with the non-specific plate in DFO. We used NCB-PT plates (Zimmer Inc.) in the upside-down position and the minimum 5-year outcomes were evaluated. The mean preoperative weight bearing line ratio and Japanese Orthopaedic Association score improved from 97.6%±35.8% and 68.0±11.5, respectively, to 44.0%±16.1% and 82.0±7.6, respectively, 1 year postoperatively and to 42.8%±15.7% and 86.0±8.2, respectively, 5 years postoperatively. The flexion range decreased from 149.0°±6.5° to 138.0°±5.7° 1 year postoperatively and to 135.0°±20.9° 5 years postoperatively. Although DFO using the NCB-PT plate provided mid-term benefits, it resulted in a loss of knee flexion, possibly due to excessive coverage of the medial femoral epicondyle.

Quantitative analysis of the Trendelenburg test and invention of a modified method.

BACKGROUND: While the Trendelenburg test has been used for 120 years to detect hip abductor muscle weakness, the methodology has not been standardised. PURPOSES: This study undertook to quantitatively analyze the relation between abductor muscle activity and pelvic tilt angle in the Trendelenburg one-leg stance, examine the pitfalls associated with performing the T-test, and develop a modified method that will produce reliable results. METHODS: A convenience sample of 15 healthy males was asked to assume a one-leg stance in ten different postures, five with mild flexion on the unsupported side, and five with severe flexion. Trunk sway angle, pelvic tilt angle, and the pelvic on femur (POF) angle were measured for each posture. Statistical analysis was used to assess differences in hip abductor activity and public tilt angle between the control posture and the test postures. RESULTS: With minimum trunk sway, hip abductor muscle activity increases when the pelvis is elevated and decreases when it is dropped. With trunk sway toward the test side, abductor muscle activity decreased when the pelvis was elevated; with trunk sway toward the non-test side, muscle activity stayed approximately constant when the pelvis was dropped. CONCLUSIONS: Based on the results we developed a modified T-test methodology that would improve reliability. This test should be performed with minimum trunk sway and severe flexion on the non-test side. The assessment of muscle weakness is based on whether the patient can keep the single-leg standing posture when forced to elevate the pelvis, not simply on the pelvic drop. In future research, we will perform the modified T-test on patients with a suspected hip abductor deficiency, and assess the usefulness of the modified test.

The paracrine effect of adipose-derived stem cells inhibits osteoarthritis progression.

BACKGROUND: This study aimed to determine whether intra-articularly injected adipose-derived stem cells (ADSCs) inhibited articular cartilage degeneration during osteoarthritis (OA) development in a rabbit anterior cruciate ligament transection (ACLT) model. The paracrine effects of ADSCs on chondrocytes were investigated using a co-culture system. METHODS: ACLT was performed on both knee joints of 12 rabbits. ADSCs were isolated from the subcutaneous adipose tissue. ADSCs with hyaluronic acid were intra-articularly injected into the left knee, and hyaluronic acid was injected into the right knee. The knees were compared macroscopically, histologically, and immunohistochemically at 8 and 12 weeks. In addition, cell viability was determined using co-culture system of ADSCs and chondrocytes. RESULTS: Macroscopically, osteoarthritis progression was milder in the ADSC-treated knees than in the control knees 8 weeks after ACLT. Histologically, control knees showed obvious erosions in both the medial and lateral condyles at 8 weeks, while cartilage was predominantly retained in the ADSC-treated knees. At 12 weeks, the ADSC-treated knees showed a slight suppression of cartilage degeneration, unlike the control knees. Immunohistochemically, MMP-13 expression was less in the ADSC-treated cartilage than in the control knees. The cell viability of chondrocytes co-cultured with ADSCs was higher than that of chondrocytes cultured alone. TNF-alpha-induced apoptotic stimulation was similar between the two groups. CONCLUSIONS: Intra-articularly injected ADSCs inhibited cartilage degeneration progression by homing to the synovium and secreting a liquid factor having chondro-protective effects such as chondrocyte proliferation and cartilage matrix protection.

Do we need intraoperative radiographs for positioning the femoral component in total hip arthroplasty?

INTRODUCTION: Poor long-term results of total hip arthroplasty (THA) can result from femoral component misalignment. There are few reports that discuss the effectiveness of intraoperative radiographs for placing femoral components. This study is a retrospective review to find out the usefulness of intraoperative radiographs in detecting and improving the femoral component misalignment in posterior-approached primary THA. MATERIALS AND METHODS: The study group included 150 primary THAs performed between September 2009 and April 2012. After the trial component insertion in lateral decubitus position, intraoperative radiography was performed. The surgeon assessed the femoral component position in three aspects: alignment, leg length, and offset. If it is not following the preoperative template, the surgeon makes the intraoperative adjustments to change the femoral component position. After the operation, postoperative radiograph was taken; the same parameters were measured and were compared to intraoperative findings. The changes in each parameter were classified into three categories: satisfactory, no change, and unsatisfactory. Among the three parameters, if one is satisfactory and the others are not unsatisfactory, we defined it as accurate positioning of the femoral component. RESULTS: Intraoperative adjustments were made in 122 cases (81.3 %). The adjustments included changes in the component size (35.3 %), component alignment (38.6 %), femoral offset (14.0 %), and additional femoral neck cuts (56.0 %). As a result, accurate positioning was successfully achieved in 112 cases (91.8 %) by taking intraoperative radiographs. CONCLUSION: Our data suggest that intraoperative radiography is a useful method for detecting the errors of placing the femoral components, and the success of a surgeon to correct those errors after detecting them intraoperatively.

Three-dimensional kinetic simulation before and after rotational acetabular osteotomy.

BACKGROUND: Some reports indicate that one of major causes of clinical failure after periacetabular osteotomy is development of secondary femoroacetabular impingement (FAI). To assess the impact of range of motion (ROM) on the increase in FAI following rotational acetabular osteotomy (RAO), we performed FAI simulations before and after RAO. METHODS: We evaluated 12 hips that had undergone RAO (study group), and 12 normal hips (control group). The study group was evaluated before and after surgery. Morphological parameters were evaluated to assess acetabular coverage. The acetabular anteversion angle, anterior CE angle, alpha angle, and combined anteversion angle were also measured. Impingement simulations were performed using 3D-CT. The ROM which causes bone-to-bone impingement was evaluated in flexion (flex), abduction, external rotation at 0° flexion, and internal rotation at 90° flexion. The lesions caused by impingement were evaluated. RESULTS: Radiographic measurements indicated improved postoperative acetabular coverage in the study group. The crossover sign was recognized pre- and postoperatively in every case in the study group and in no cases in the control group. In the simulation study, flexion, abduction, and internal rotation at 90° flexion decreased postoperatively. Impingement occurred within 45° internal rotation at 90° flexion in two preoperative and nine postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. There were correlations between anterior CE angle, CE angle, acetabular anteversion angle, and hip flexion angle. There were also correlations between the anterior CE angle, combined anteversion angle, and angle of internal rotation at 90° flexion. CONCLUSIONS: In the postoperative simulation, there was a tendency to reduce the ROM in flexion, abduction, and internal rotation at 90° flexion due to impingement. Since there were more cases which caused impingement within 45° internal rotation at 90° flexion after RAO, we consider there is a potential for increased FAI after RAO.

The value of computed tomography based navigation in revision total hip arthroplasty.

PURPOSE: This study investigates the accuracy of a computed tomography (CT)-based navigation system for accurate acetabular component placement during revision total hip arthroplasty (THA). METHODS: We performed a retrospective review of 30 hips in 26 patients who underwent cementless revision THA using a CT-based navigation system; the control group consisted of 25 hips in 25 patients who underwent cementless primary THA using the same system. We analysed the deviation of anteversion and inclination angles among the pre-operative plan, intra-operative records from the navigation system and data from postoperative CT scans. RESULTS: There were no significant differences between groups (P < 0.05) in terms of mean deviation between pre-operative planning and postoperative measurements or between intraoperative records and postoperative measurements. CONCLUSION: CT-based navigation in revision THA is a useful tool that enables the surgeon to implant the acetabular component at the precise angle determined in pre-operative planning.