Possibility of Predicting Pelvic Inclination Following Total Hip Arthroplasty Based on the Preoperative State: Sacral Slope and Pelvic Incidence Minus Lumbar Lordosis as Predictive Factors

Following total hip arthroplasty (THA), some patients exhibit anterior or posterior pelvic tilt (PT). This case– control study investigated whether changes to PT following THA can be preoperatively predicted. Methods: 135 patients with hip osteoarthritis who underwent THA were assessed. The parameters measured preoperatively and one year postoperatively were lumbar lordosis (LL) based on plain X-ray and pelvic incidence (PI), PT, and sacral slope (SS), all of which were measured as pelvic morphological angles. Patients were classified into groups (A–E) based on the degree of post-THA PT, and their preoperative conditions were compared. PI minus LL was used to evaluate spinal alignment and pelvic balance. Results: Overall, 33%, 30%, 21%, 13%, and 3% of the hips of patients in Groups A, B, C, D, and E were postoperatively assessed. In Groups A–E, the SS values were 34.6°±8.9°, 37.6°±8.4°, 37.9°±8.9°, 42.6°±9.5°, and 60.0°±11.1°, whereas the PI minus LL values were 2.9°±15.0°, 1.2°±13.6°, 3.6°±17.7°, 12.7°±13.1°, and −1.3°±11.7°, respectively. Conclusions: Following THA, 70% of patients experienced posterior PT. Pre-THA SS ≥45° or PI minus LL ≥15° signified marked postoperative posterior tilt and could predict postoperative PT following THA. These findings are useful for implant placement, as they can predict pelvic inclination

Factors Associated with Surgical Field Bacterial Detection during Total Hip Arthroplasty

Total hip arthroplasty (THA) provides relief from hip pain and improves hip function. However, periprosthetic joint infection (PJI) remains an area of concern. We examined the detection rate of bacteria from surgical fields in wound closure, along with the relationship between bacterial detection rate and type of antiseptic, surgery time, and surgeon experience for 500 patients who underwent THA at our department. The mean age at surgery was 64.3 (± 27.3) years. The bacterial detection rate was 4.6%. None of the cases revealed PJI. No significant association between the detection rate and type of antiseptic used or surgery time was observed. However, for patients treated by surgeons with < 10 years of orthopedic experience, a detection rate of 7.3% was found, while a rate of 1.3% was observed for those treated by surgeons with ≥ 10 years of orthopedic experience. This finding indicated that orthopedic experience of less than 10 years was significantly associated with an increased bacterial detection rate (chi-square test, p=0.002). The detection rate was associated with surgeon experience but not with antiseptic type or surgery time. It is possible that intraoperative handling may increase the number of bacteria in surgical fields in wound closure

Survey of Shoulder Osteoarthritis in Patients who Underwent Total Hip Arthroplasty for Hip Osteoarthritis

To the best of our knowledge, no previous studies have reported a relationship between osteoarthritis (OA) of the lower limbs and OA of the shoulder joints. We evaluated the correlation between shoulder OA and hip OA. We collected contrast-enhanced computed tomography (CECT) images of the shoulder joints of 159 patients with hip OA who underwent primary total hip arthroplasty (THA). The images, taken 1 week after THA to monitor venous thromboembolism (VTE), were used to examine the prevalence of shoulder OA. They were compared with those of 103 controls who underwent CECT during the same period to monitor VTE. Shoulder OA was observed in 15% of the controls and 24% of the THA patients. Although the rate was somewhat higher in the THA group, the difference was not significant. However, in the THA group, significantly more patients with bilateral hip OA (33%) had shoulder OA than those with unilateral hip OA (17%). In summary, the prevalence of shoulder OA was significantly higher in patients with bilateral hip OA. In these patients, pain and instability in the hip joints require them to use arm support to stand up or walk, putting the weight-bearing shoulder at risk of developing OA

Survey of Osteoarthritis of the Shoulder in Patients who Underwent Knee Arthroplasty for Knee Osteoarthritis

The relationship between osteoarthritis (OA) of the lower extremity and shoulder OA has not been established. This study evaluated the prevalence of shoulder OA in patients with knee OA. We collected contrast-enhanced computed tomography (CECT) images of the shoulder joints of 105 patients with knee OA that were taken 1 week after they underwent primary knee arthroplasty to check for venous thromboembolism (VTE). The images were compared with CECT images of 110 control-group patients that were taken for the purpose of differentiating VTE. Shoulder OA was present in a significantly higher percentage of patients with knee arthroplasty than controls (29% versus 15%), and the difference was particularly pronounced in patients in their 70s (33%) compared to age-matched controls (11%). Patients with knee OA often use arm support to stand up or walk due to knee joint pain and muscle weakness, which places the weight-bearing shoulder at risk of developing OA

Evaluation of the appropriate reaming diameter during initial fixation of a cementless hip prosthesis

　Background: Press-fit fixation is important technical factor to achieve initial stability of a cementless acetabular cup for good clinical results of total hip arthroplasty. However, appropriate reaming diameter during initial fixation is unclear. Therefore, this study aimed to evaluate the optimal reaming diameter using simulated bones and cementless cups.　Methods: Three types of simulated bones with different degrees of hardness were used (10 pcf, 20 pcf, 30 pcf, pcf = 16.02 kg/㎥). Acetabular models were created by reaming the simulated bone into a hemisphere, and the reaming diameters were 48 mm, 49 mm, and 50 mm.The 50 mm diameter acetabular cup was fixed to simulated bones with a compressive load of 16,000 N at a rate of 12 mm/min. The testing machine was attached to a cup fixed to the simulated bone, and a pull-out test, rotation test, and lever-out test were performed. To evaluate the initial gap, ink was applied to the cup surface during the pull-out test, and the contact between the bone and cup was visually evaluated after pull-out.　Results: The pull-out load of the 20 and 30 pcf simulated bones was significantly lower at a reaming diameter of 50 mm that those at reaming diameters of both 48 and 49 mm (P < 0.05). The rotational torque of the 20 and 30 pcf simulated bones was significantly lower at a reaming diameter of 50 mm that those at reaming diameters of both 48 mm and 49 mm (P < 0.05). The lever-out moment of the 20 and 30 pcf simulated bones was significantly lower at a reaming diameter of 50 mm than those at reaming diameters of both 48 mm and 49 mm (P < 0.05).Contact between the 30 pcf simulated bone and the cup at a reaming diameter of 48 mm was mainly at the edge of the cup; contact at the center of the cup was poor.　Conclusions: We performed mechanical tests using simulated bones and evaluated the initial fixation of the cup according to the bone reaming diameter. We recommend under-reaming by 1 mm in all cases to optimize both initial fixation capacity and contact between acetabular cup and bone

Changes in sagittal spino-pelvic alignment after total hip arthroplasty using the Roussouly classification

Pelvic inclination changes after total hip arthroplasty; we determined how sagittal spino-pelvic alignment changed after total hip arthroplasty. We investigated the change in Roussouly classification type and sagittal spino-pelvic alignment after total hip arthroplasty. Sagittal spino-pelvic alignment was investigated in 135 patients who underwent total hip arthroplasty. Prior to surgery, there were 50 cases (37%) of Type 1 and 2, 53 cases (39.3%) of Type 3, and 32 cases (23.7%) of Type 4. Since none of the Type 1 and 2 cases showed postoperative changes, we divided the Type 3 and Type 4 cases into 3 groups. Cases with pelvic retroversion and reduced lumbar lordosis before total hip arthroplasty showed no change. Half of the cases with satisfactory preoperative sagittal spino-pelvic alignment (SSPA) remained Type 3 with lumbar lordosis even after surgery. However, even in satisfactory Type 3 cases, if there was pelvic retroversion after total hip arthroplasty (THA) surgery, they were reclassified as Type 1 or 2 due to reduced lumbar lordosis and changes in SSPA. Cases of Type 4 with preoperative pelvic anteversion were reclassified as Type 3 after surgery due to a major reduction in the sacral slope angle and changes in SSPA

Screwless Cup 摺動部の接触面圧力の力学的解析

セメントレスTHA において安定したスクリューレスCup の初期固定を得るには，高い回旋開始時トルク値で初期固定力を確保し，高範囲かつ適切な接触領域の分布を示すことが重要と考える．これまでCup の接触面積がどの程度減少してしまうと，固定力に影響するか力学試験解析した報告は少ない．Cup 摺動部の接触領域を変化させ，実際のヒト寛骨臼の硬さを想定したボーンモデルを作製しフィンの有無が与える影響について力学試験を行った．Cup の辺縁全周が接触するように1mm のアンダーリーミングを行った後に，臼蓋形成不全による骨欠損の有無の影響を考慮し，Cup が臼蓋縁よりはみ出すように骨モデルを10°，20°，30°，40°の角度をつけてカットした骨欠損モデルと，術中の臼蓋に対し再リーミングを想定し1，2，3，6，9mm 偏心したモデルにおいて検討した．骨欠損モデルでは接触面積が10°：94.4%，20°：88.9％，30°：83.3%，40°：78.6％と小さくなり，偏心モデルにおいては1mm：60.4%，2mm：56.7%，3mm：56.2%，6mm：57.8%，9mm：60.4% と6mm 以上の偏心で接触面積は再増加した．最大トルク値では，フィン有りは0°：60.1N/m，10°：58.8N/m，20°：50.2N/m，30°：25.3N/m, 40°：17.4N/m．フィン無しは0°：46.2N/m，10°：40.4N/m，20°：23.5N/m，30°：13.9N/m，40°：7.4N/m であった．フィンの有無に関わらず30°で回旋トルクが著明に低下していた．力学試験においては30°以上において回旋トルク値が極端に低下した．偏心モデルでは2mm 以上で回旋トルクが極端に低下した．結論として，骨との接触面積が減少し，さらにはフィンの掛かりが減少したことが，回旋力低下の要因に大きく影響した．In order to achieve stable initial fixation of a screwless cup in cementless total hip arthroplasty (THA), the initial fixation strength has to be assured at a high torque value on initial rotation, and demonstrating a high range and an appropriate contact area distribution is considered important. To date, there have been few reports discussing the quantitative analysis of how much the contact surface area of the cup has to decrease before the fixation strength of a press-fit cup is affected.In the present study, the contact surface area of the sliding portion of the cup was varied, and this contact surface area was varied in order to conduct comparison testing of mechanical properties, to see whether there was any impact caused by the presence or absence of fins. Bone models were prepared presuming the hardness of actual human acetabula, and their mechanical properties were tested. After performing 1-mm underreaming so that the entire rim of the cup was in contact, taking into consideration possible effects from the presence or absence of bone defects caused by acetabular aplasia, bone defect models were cut so that the cup protruded beyond the rim of the acetabular cartridge and angles of 10 °, 20 °, 30 ° and 40° were created, and, presuming re-reaming with respect to the acetabula during surgery, models with 1-, 2-, 3-, 6-, and 9-mm eccentricity were tested. With the bone defect models, the contact surface area decreased (10°, 94.4%; 20°, 88.9%; 30°, 83.3% and 40°, 78.6%), while in the eccentricity models, the contact surface area increased again at eccentricities of 6 mm or more (1mm, 60.4%;2mm, 56.7%; 3 mm, 56.2%; 6 mm, 57.8%; and 9 mm, 60.4%). In the models with fins, the maximum torque values were as follows: 0°, 60.1 N/m; 10°, 58.8 N/m; 20°, 50.2 N/m; 30°, 25.3 N/m and 40°, 17.4N/m. In the models without fins, the values were as follows: 0°, 46.2 N/m; 10°, 40.4 N/m; 20°, 23.5 N/m; 30°, 13.9 N/m and 40°, 7.4N/m. There was an extreme decrease in the rotational torque value at 30 ° or more, compared to that at 20 °. In models in which eccentricity was applied, at 2 mm or more, when it is difficult for the fins to engage, there was an extreme decrease in the rotational torque. In conclusion, the decrease in the contact surface area between the cup and bone and the reduced engagement of the fins strongly affected the decrease in rotational force

Evaluation of the appropriate reaming diameter during initial fixation of a cementless hip prosthesis

Regular Articlejournal articl

Changes in sagittal spino-pelvic alignment after total hip arthroplasty using the Roussouly classification

Regular Articlejournal articl