Improving the accuracy of tibial component placement during total knee replacement in varus knees with tibial bowing: A prospective randomised controlled study

BackgroundLateral tibial bowing leads to varus placement of the tibial component during total knee replacement in varus knees. Lateralised tibial jig placement can improve the accuracy of the tibial cut.MethodsA total of 227 patients (300 knees) undergoing total knee replacements were randomised into two groups. In the study group, the point of intersection of the distal tibial diaphyseal line at the tibial plateau drawn on long films was represented by zones. Knees with femoral bowing > 5° (28%) were excluded. Tibial jig placement on the proximal tibia was lateralised according to the zones. In the control group, the mid-point of the tibial plateau was taken as a reference. Femoral and tibial bowing, postoperative limb alignment and component placement were assessed.ResultsOf the 216 knees that were studied, 106 were in the study group and 110 in the control group. Bowing ≥ 3° had a significant positive correlation with lateralisation of the proximal tibial reference (p < 0.001). The Incidence of tibial bowing ≥ 3° was 57.33%. The mean postoperative hip–knee–ankle (HKA) angle was 178.31 ± 2.88° and 176.53 ± 2.88° (p < 0.001), whereas the mean medial proximal tibial angle (MPTA) was 89.91 ± 1.42° and 88.79 ± 1.72° (p < 0.001) in the study and control groups, respectively. Considering bowed tibiae alone, HKA angle and MPTA in the study group were 178.08 ± 2.81° and 89.72 ± 1.39° compared with 175.88 ± 2.87° and 88.38 ± 1.38° in the control group (p < 0.001).ConclusionThere is a high incidence of tibial bowing in varus knees. Lateralised tibial jig placement improved tibial component placement and postoperative limb alignment in total knee arthroplasty in varus knees with tibial bowing.     

Patient specific instrumentation allow precise derotational correction of femoral and tibial torsional deformities

BackgroundRotational malalignment deformities of the lower limb in adults mostly arise from excessive femoral anteversion and/or excessive external tibial torsion. The aim of this study was to assess the correction accuracy of a patient specific cutting guides (PSCG) used in tibial and femoral correction for lower-limb torsional deformities.MethodsForty knees (32 patients) were included prospectively. All patients had patellofemoral pain or instability with torsional malalignment for which a proximal tibial (HTO) or distal femoral (DFO) or a double-level osteotomy (DLO) had been performed. Accuracy of the correction between the planned and the postoperative angular values including femoral anteversion, tibial torsion, coronal and sagittal alignment were assessed after tibial and/or femoral osteotomy.ResultsForty knees were included in this study. In cases of HTO, the correction accuracy obtained with PSCG was 1.3 ± 1.1° for tibial torsion (axial plane), 0.8 ± 0.7° for MPTA (coronal plane) and 0.8 ± 0.6° for PPTA (sagittal plane). In cases of DFO, the correction accuracy obtained with PSCG was 1.5 ± 1.4° for femoral anteversion (axial plane), 0.9 ± 0.9° for LDFA (coronal plane) and 0.9 ± 0.9° for PDFA (sagittal plane). The IKSG was improved from 58.0 ± 13.2° to 71.4 ± 10.9 (p = 0.04) and the IKSF from 50.2 ± 14.3 to 87.0 ± 6.9 (p < 0.001).ConclusionsUsing the PSCG for derotational osteotomy allows excellent correction accuracy in all the three planes for femoral and tibial torsional deformities associated with patellofemoral instability.Level of clinical evidence II, prospective cohort study.     

Medial meniscus extrusion and stage are related to the size of spontaneous osteonecrosis of the knee in patients who underwent high tibial osteotomy

PurposeSpontaneous osteonecrosis of the knee (SONK) causes acute atraumatic knee pain, and meniscus tears may be associated with the pathogenesis of SONK. The purpose of this study was to investigate the relationship of the type of meniscus tear and medial meniscus extrusion with SONK on the medial femoral condyle in patients who underwent surgical treatment with high tibial osteotomy due to severe knee pain.MethodsWe enrolled 98 patients with 102 knees who underwent medial opening wedge high tibial osteotomy (OWHTO) under the diagnosis of medial femoral condyle osteonecrosis at our hospital from December 2003 to January 2020. Based on the Koshino classification, cases of SONK were classified as stage 1–4. The relationships of demographic data, X-rays and MRI images, including femorotibial angle (FTA), meniscus tear type, and medial meniscus extrusion (MME), with the stage and volume of SONK were investigated.ResultsNinety-eight patients (29 males and 69 females), with an average age at surgery of 69.2 ± 9.6 years and Body mass index(BMI) of 61.0 ± 17.6 kg/m². In 102 cases of SONK, 11 knees, 18 knees, 46 knees, and 27 knees were classified as stage 1–4, respectively. The mean SONK volume was 2161.61 µm (range 95.67–7484.68 µm) on preoperative MRI. The preoperative FTA (mean 180.86°, range 172–187°) was not associated with the stage or volume of SONK. Meniscus tears were found in all cases of SONK and consisted of 2 degenerations, 2 horizontal tears, 0 vertical tears, 40 radial tears, 4 complex tears, and 54 medial meniscus posterior root tears (MMPRTs). In addition, 99% (101/102) of knees showed more than 3 mm of meniscus extrusion. Although the meniscus tear type was not associated with SONK stage, there was a high rate of tears that caused disruption of the hoop strain, such as MMPRTs (52.9%) or radial tears (39.2%). MME was significantly related to SONK volume (r = 0.387, p < 0.001).ConclusionAll patients with SONK had coexisting meniscus tears, most menisci had medial extrusion, and a positive correlation was observed between MME and SONK volume.     

胫骨髁外翻截骨术治疗创伤性膝关节炎的早期临床疗效分析

目的 探讨胫骨髁外翻截骨术（TCVO）治疗陈旧性内侧胫骨平台骨折并发创伤性膝关节炎（TKOA）的早期临床疗效。方法 回顾性分析2016年6月至2021年6月于苏州市立医院关节外科接受TCVO手术治疗陈旧性内侧胫骨平台骨折并发TKOA的18例患者的术前及术后相关临床资料,所有患膝均为陈旧性内侧胫骨平台骨折保守治疗后畸形愈合并发膝内翻TKOA。患者发生胫骨平台骨折至TCVO手术治疗的时间为49 ～ 171个月,平均（111.1±33.8）个月;患膝内翻角度为6.81° ～ 14.49°,平均10.95°±2.62°;关节线会聚角（JLCA）为3.58° ～ 8.12°,平均5.95°±1.42°。所有患者于术前及术后3个月拍摄站立位双下肢全长X线片、膝关节正侧位X线片并测量患膝内翻角度、胫骨近端内侧角（MPTA）、JLCA、胫骨平台后倾角（PTS）,评估术前、术后下肢力线以及膝关节对合状态的变化情况。依据术前及术后3、12个月的患膝关节活动度（ROM）、疼痛视觉模拟评分（VAS）、西安大略与麦克马斯特大学（WOMAC）骨关节炎指数、膝关节损伤与骨关节炎评分（KOOS）评估早期临床疗效。结果 18例患者均获得随访,随访时间为14 ～ 65个月,平均随访（27.4±14.4）个月。术后3个月时,患膝内翻角、JLCA均较术前显著降低,差异均具有统计学意义（P＜0.05）;MPTA与术前相比有显著提升,差异有统计学意义（P＜0.05）;PTS与术前相比差异无统计学意义（P＞0.05）。术后3、12个月时,患膝关节ROM、VAS、WOMAC、KOOS评分均较术前有显著好转,差异均具有统计学意义（P＜0.05）。结论 采用TCVO治疗陈旧性内侧胫骨平台骨折并发TKOA可以取得良好的早期临床疗效,有效矫正膝关节内翻畸形,缓解膝关节疼痛及改善膝关节功能。     

Comparative outcomes of patient-specific instrumentation,the conventional method and navigation assistance in open-wedge high tibial osteotomy: A prospective comparative study with a two-year follow up

BackgroundTo compare and analyze the correction precision, clinical outcomes and complications among the three methods of performing open-wedge high tibial osteotomy (HTO), including patient-specific instrumentation (PSI), conventional method and navigation assistance.MethodsIn this prospective, single-center study, we randomly assigned patients with knee osteoarthritis in a 1:1:1 ratio to undergo Open-wedge high tibial osteotomy (OWHTO) with conventional method, navigation assistance or PSI. The primary outcome was the target/observed hip–knee–ankle (HKA) angle difference at 1 month postoperatively. Secondary outcomes were changes in the postoperative posterior tibial slope (PTS) at 1 month and clinical outcomes including knee pain on a visual analogue scale (ranging from 0 to 100, with higher scores indicating more severe pain), Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (ranging from 0 to 240) scores at 1 month, 6 months, 12 months, and 24 months.ResultsFrom 2017 through 2019, a total of 608 patients were screened; of those patients, 144 were enrolled, with 48 in each group. The primary outcome of the HKA difference was 2.6 ± 2.0° in the conventional group, 2.3 ± 1.5° in the navigation group and 0.6 ± 1.0° in the PSI group (P < 0.001). Secondary outcomes including changes in the postoperative PTS and clinical outcomes at 1 month, 6 months, and 12 months were in the same direction as the primary outcome. There were no significant differences in the complications among the three groups.ConclusionsIn the present study, none of the three methods showed superiority in objective correction precision and clinical outcomes at 2 years.     

Coronal tibiofemoral subluxation is a risk factor for postoperative overcorrection in high tibial osteotomy

BackgroundSevere tibiofemoral (TF) subluxation > 10 mm is a contraindication for high tibial osteotomy (HTO). However, the relationship between the degree of preoperative TF subluxation at < 10 mm and postoperative radiographic/clinical outcomes remains unclear.MethodsSixty-seven patients who underwent open wedge HTO with a planned postoperative mechanical femorotibial angle (mFTA) of three degrees valgus were retrospectively studied. The minimal subluxation (MIN) group included 39 patients with TF subluxation < 5 mm, while the moderate subluxation (MOD) group included 28 patients with TF subluxation of five to 10 mm. The preoperative and one-year postoperative mFTA, TF subluxation, medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), preoperative Kellgren-Lawrence (K–L) grade and varus-valgus laxity were evaluated. Clinical scores and pain visual analogue scale (VAS) were also analyzed.ResultsThe mean preoperative TF values in the MIN and MOD groups were 3.1±1.0 mm and 6.7±1.6 mm (mean±standard deviation, p < 0.001), respectively, with no significant difference in K–L grades. The MIN group demonstrated a significantly smaller varus preoperative mFTA (p < 0.001), larger MPTA (p = 0.011), smaller JLCA (p = 0.004), and less varus laxity (p = 0.023). Postoperative TF subluxation, MPTAs, and JLCAs did not differ significantly between the two groups, while the postoperative mFTA was significantly different (p = 0.001), with unintended overcorrection in the MOD group. No significant difference in clinical scores and VAS were observed.ConclusionsAfter HTO, compared to patients with TF subluxation < 5 mm, patients with TF subluxation of five to 10 mm were more likely to demonstrate unintended valgus overcorrection on one-year postoperative radiography.     

Approximately 80% of Japanese osteoarthritic patients fall out of the safety range in restricted kinematically-aligned total knee arthroplasty in an analysis of preoperative long-leg radiograms

BackgroundRestricted kinematically-aligned total knee arthroplasty (KA-TKA) is a reasonable modification to avoid the alignment outlier that may cause implant failure. However, despite a noted high incidence of constitutional varus in Japanese individuals, there has been no investigation into how many knees require the restriction in restricted KA-TKA (RKA-TKA) among Japanese patients. Therefore, we conducted a study using preoperative long-leg radiograms.MethodsWe studied long-leg radiographs of 228 knees in 114 consecutive patients. The numbers of knees within the safety range and their corrective osteotomy angle in the restriction algorithms advocated by Almaawi et al. (2017) and MacDessi et al. (2020) were evaluated.ResultsAccording to the algorithms used by Almaawi et al. and MacDessi et al., out of 228 knees, 46 (20%) and 39 (17%) fell within the safety range, respectively. The mean correction angles of the hip-knee-ankle angle, lateral distal femoral angle and medial proximal tibial angle were 2.8 ± 3.4°, 0.4 ± 1.4° and 2.4 ± 2.8° in the algorithm used by Almaawi et al., while they were −4.9 ± 4.7°, 1.1 ± 2.5° and −6.0 ± 3.4° in the algorithm used by MacDessi et al. Most of the knees needed to be restricted in order to perform RKA-TKA, regardless of the algorithm used.ConclusionsBased on a preoperative analysis of long-leg radiograms in a Japanese population, most knees fall out of the safety range in RKA-TKA. Surgeons must consider whether to allow component outlier or to perform corrective osteotomy that likely requires soft tissue release.     

Management of early and late presenting tibial stress fracture with advanced osteoarthritis of the knee: A dilemma among arthroplasty surgeons in developing countries

BackgroundSingle-stage total knee arthroplasty (TKA) with long-stem is a viable option to treat proximal tibial stress fracture in advance knee osteoarthritis. However, in patients with old mal-united or non-united tibial fractures, treatment becomes complicated. Therefore, our aim in this study was to monitor clinical and radiological outcome in patients presenting early or late managed by single-stage long-stem TKA.MethodsThis retrospective study included 24 consecutive patients; all were female. Patients with recent and mobile stress fracture (Group A) were treated with close reduction and long-stem tibial component. However, in patients with old, sclerotic or mal-united fractures (Group B), open reduction, partial fibulectomy and plating with bone grafting was also performed. Outcome was monitored by tibiofemoral angle, functional Knee Society score and time taken for union.ResultsThe mean age of patients was 62.34 years. There were 13 patients in Group A and 11 in Group B. The mean follow up was 42.79 months (range, 18–72 months). Knee Society score improved from 29.83 ± 6.10 to 91.57 ± 4.89 in Group A and from 27.21 ± 3.32 to 89.87 ± 3.89 in Group B. Tibiofemoral angle improved from 20.57 ± 3.00° to 0.80 ± 0.46° in 21 varus knees, whereas it improved from 22.33 ± 4.61° to 0.83 ± 0.28° in three valgus knees. Iatrogenic perforation of tibial cortex occurred in one case. Union of stress fracture was achieved in all cases with a mean duration of 4.70 months.ConclusionExcellent results were obtained in both groups but were slightly lower in patients presenting late, therefore all efforts must be made to treat such cases as early as possible.     

Dome-shaped high tibial osteotomy with semi-circular Ilizarov pin fixator: Mid- to long-term results of a novel technique

BackgroundThe aim of this study was to assess the clinical and radiological results of the dome-shaped high tibial osteotomy (HTO) which was fixed with a novel construct comprised of semi-circular Ilizarov frames and pins.MethodsThe patients with at least five years of follow-up were evaluated. One-hundred and thirty-two knees of 114 patients were included in the final analysis. The clinical evaluation included range of motion and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. Anatomical femorotibial angle (aFTA), anatomical medial proximal tibial angle (aMPTA), tibial slope and Insall–Salvati ratio were calculated on standard weight-bearing radiographs.ResultsThe average aFTA was improved from 1.6° varus to 8.7° valgus (P < 0.001). The average WOMAC score (P < 0.001) and flexion value (P = 0.014) were improved at the latest follow-up (WOMAC: 17.2, flexion: 142.5) compared with the preoperative period (WOMAC: 59.6, flexion: 129.2). The sagittal radiological parameters were not significantly affected. The five-year survival was 96.2%, and 10-year survival was 83.3%.ConclusionsThe semi-circular Ilizarov pin construct provided satisfactory outcomes both clinically and radiologically at mid- to long-term follow-up.     

A novel anteroposterior axis of the tibia for total knee arthroplasty: An upright weight-bearing computed tomography analysis

BackgroundThe traditional anteroposterior (AP) axis (i.e., Akagi’s line) has been widely used as the tibial component AP axis during total knee arthroplasty (TKA). However, this AP axis has been defined based on computed tomography (CT) in a non-weight-bearing supine position. In this study, AP axes of the tibial plateau from upright CT in weight-bearing and non-weight-bearing positions were determined and compared.MethodsThis study included 43 knees from 23 healthy volunteers. CT images were obtained in weight-bearing and non-weight-bearing standing positions using a 320-detector row upright CT scanner. The line perpendicular to surgical transepicondylar axis projected onto the tibia plateau was determined as the AP axis in upright weight-bearing and non-weight-bearing conditions. Angular differences between these two conditions were measured.ResultsThe upright weight-bearing AP axis was positioned in a mean of 7.4 ± 4.3° of internal rotation relative to the traditional AP axis. Distance between the traditional and upright weight-bearing AP axis was 2.9 ± 1.6 mm at the edge of the tibial plateau. The upright non-weight-bearing AP axis was positioned in a mean of 3.5 ± 4.1° of internal rotation relative to the traditional AP axis. Mean angular difference between weight-bearing and non-weight-bearing conditions was 3.9 ± 4.1°.ConclusionsThe upright weight-bearing AP axis was positioned in 7.4° of internal rotation relative to the traditional AP axis, showing one-seventh of the tibial tuberosity away from the medial border of the tibial tubercle, which represents a practical landmark for the tibial component AP axis during TKA.     

3D打印辅助胫骨高位开放截骨联合关节镜治疗膝内翻畸形临床疗效分析

目的观察3D打印截骨导板辅助胫骨高位开放式截骨术(OWHTO)联合关节镜清理治疗膝关节内翻畸形的临床疗效。方法回顾性分析2017年1月至2018年5月本院骨伤科膝关节内翻畸形患者15例(16膝)。术前利用3D打印截骨导板模拟OWHTO,根据理想的术后下肢力线(WBL),确定截骨部位、合页、高度、宽度、胫骨平台后倾角(PTS)及锁定钢板模型,进行截骨内固定。对术前术后WBL、Lysholm评分、PTS、髌骨高度指数(Caton指数)进行比较。结果随访15~24个月,WBL术前为(19.27±1.55)%,3D打印设计为(61.91±0.24)%,术后WBL恢复到(60.54±0.84)%,术前术后有统计学差异,3D打印设计与术后实际对比无统计学差异;术前术后PTS分别为(10.01±2.89)°,(10.06±0.09)°,无统计学差异;术后1年Lysholm评分(82.31±1.22)分,与术前(34.75±1.87)分比较差异有统计学意义。结论3D打印截骨导板辅助OWHTO,可实现精确截骨,显著改善下肢力线,减少术中透视,节省手术时间,是治疗膝关节内翻畸形安全有效的方法。     

External rotation of the tibial component should be avoided in lateral unicompartmental knee arthroplasty

BackgroundLateral unicompartmental knee arthroplasty (UKA) leads to good clinical outcomes for isolated lateral osteoarthritis. However, the impact of the tibial component position on postoperative outcomes in lateral UKA is yet to be determined.PurposeThis study investigated the influence of tibial component malposition on clinical outcomes in lateral UKA.MaterialsThis was a retrospective study of 50 knees (mean age 73.5 years) who underwent lateral UKA between September 2013 and January 2019. The Oxford Knee Score (OKS), Knee Society Score – Knee (KSSK), and Knee Society Score – Function (KSSF) were evaluated. The coronal alignment, posterior slope of tibial component, tibial component rotation relative to Akagi’s line (angle α), and femoral anteroposterior (AP) axis (angle β) were measured postoperatively. The average follow up period was 2.3 (range, 1–4.9) years.ResultsClinical scores were significantly improved after lateral UKA. The mean coronal alignment was 0.9° ± 3.2° varus (range, 9.1° varus to 5.5° valgus), the mean posterior slope was 6.8° ± 3.8° (range, 0.8° to 14.8°). The mean α and β angles, were 4.1° ± 5.8° (range, −9.7° to 16.5°) and 6.7° ± 7.1° (range, −7.0° to 20.5°) external rotation. The angle α had significant negative correlations with postoperative OKS (r = −0.36), KSSK (r = −0.28), and KSSF (r = −0.39), and angle β had significant negative correlations with postoperative OKS (r = −0.34) and KSSK (r = −0.46).ConclusionExcessive external rotation of the tibial component could negatively influence the postoperative outcomes of lateral UKA.     

Multiplanar correction of proximal tibial recurvatum deformity with tibial osteotomy and computer assisted fixator

BackgroundSeveral treatment modalities including open wedge osteotomies and Ilizarov reconstruction have been described for treatment of Proximal tibial recurvatum (PTR). However, the literature lacks information regarding the multiplanar correction of PTR using the computer assisted hexapod external fixator. The aim of the study is to present the results of PTR treatment with a computer assisted fixator systems.MethodsThere were three female and three male patients (10 lower extremities) with a mean age of 20.6 years (7.3 to 25.2y) in the study group. The angle of genu recurvatum (aGR), the tibial plateau tilt angle (aTP), the mechanical posterior proximal tibial angle (mPPTA) and sagittal mechanical axis deviation (MADs) was measured for the sagittal plane assessment.ResultsPreoperative sagittal assessment showed that the mean aGR was 28.9°±6.8°, mean aTP was 64.5°±10.2° and mean mPPTA was mPPTA was 114.1° ±10.3°. At the final follow-up there was a significant correction (p < 0.05 for aGR, aTP and mPPTA). Mean MADs was improved from 66.1 ± 14.2 mm to 16.6 ± 5.1 mm (p:0.005). Mean A:B ratio was 0.92 ± 0.13 preoperatively and 0.89 ± 0.14 postoperatively (p:0.37). Nine out of 10 knees had valgus deformity and mean preoperative tibiofemoral anatomic angle (TFA) was improved from 10.8°±3.7° valgus to 6.5°±1.7° valgus.ConclusionThe treatment of PTR deformity with a computer-assisted hexapod external fixator is safe and effective. It provides multiplanar correction of the deformity with a high precision and the patellar alignment remains stable during the correction.     

The weight-bearing scanogram technique provides better coronal limb alignment than the navigation technique in open high tibial osteotomy

BackgroundSuccessful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The present study investigated whether the weight-bearing limb scanogram (WBS) technique provided a more accurate mechanical axis realignment than the navigation technique in open high tibial osteotomy (OHTO).MethodsThis prospective study involved 80 knees (78 patients) undergoing OHTO. The WBS technique was used in 40 knees and the navigation technique in 40 knees. Each technique was performed by a different surgeon in a different hospital. Postoperative coronal limb alignment was assessed using the weight-bearing line (WBL) ratio on full-length standing hip-to-ankle radiographs.ResultsWe found that the mean postoperative WBL ratio was greater in the WBS compared to the navigation group (p = 0.001), and hence the ratio for the WBS group was closer to the ratio target of 62%. There was a greater proportion of WBL ratio outliers in the navigation group than the WBS group (25% vs. 10%, p = 0.034).ConclusionWe conclude that the WBS technique was more accurate than the navigation technique for restoration of coronal leg alignment in OHTO.Level of EvidenceLevel II.     

Anterior and rotational tibial subluxation in the setting of anterior cruciate ligament injuries: An MRI analysis

BackgroundThe relationship between preoperative tibiofemoral position and failure of anterior cruciate ligament (ACL) reconstruction has been widely discussed. Most established methods for measuring tibiofemoral position on magnetic resonance imaging (MRI) mainly focus on anterior tibial subluxation (ATS), while a quantitative measuring method for rotational tibial subluxation (RTS) is still undetermined. Moreover, there are still controversies about the related factors for ATS. The aim of this study was to quantitatively describe preoperative ATS and RTS in ACL-injured and ACL-intact knees and identify the related factors for ATS and RTS based on MRI images.MethodsDemographic data and preoperative MRIs of 104 ACL-injured patients were retrospectively analyzed. ACL-intact knees were 1:1 matched as control group. ATS was measured using longitudinal tibial axis, and RTS was determined by the difference between lateral and medial ATS. Related factors for ATS and RTS were examined.ResultsIncreased lateral ATS (P < 0.0001), medial ATS (P < 0.0001) and RTS (P = 0.0479) were observed in ACL-injured knees compared with the control group. Increased posterior tibial slope (PTS), Beighton Score ≥ 4, presence of meniscal injury and long injury-to-MRI time were identified as being correlated with the increase of ATS. Factors for the increase of RTS were increased lateral PTS, Beighton score ≥ 4, presence of lateral meniscal injury, and left side.ConclusionsIn ACL-injured knees, tibia not only subluxated anteriorly in both lateral and medial compartments, but also rotated internally. During preoperative planning, attentions should be paid to the factors that are correlated with altered tibiofemoral position.     

Referencing the substitute anteroposterior line of the tibia improves rotational alignment of the tibial component in medial unicompartmental knee arthroplasty

BackgroundThere is no consensus regarding how best to determine the tibial rotational alignment in unicompartmental knee arthroplasty (UKA). The purpose of this study was to clarify whether using the substitute anteroposterior (sAP) line of the tibia, as has recently been proposed, can improve tibial rotation.MethodsThe study included 57 consecutive medial UKAs. From May 2015 to September 2016, 28 knees in 28 patients underwent UKA using the medial intercondylar ridge (MIR) line as the tibial anteroposterior (AP) reference (MIR group). From October 2016 to March 2018, 29 knees in 29 patients underwent UKA using the sAP line (sAP group). In both groups, the external rotation angle of the tibial component relative to a line perpendicular to the surgical epicondylar axis was measured using computed tomography-based three-dimensional preoperative planning software for TKA and UKA.ResultsThe mean external rotation angles of the tibial component in the MIR and sAP groups were 5.2° ± 8.5° (range, − 12.4° to 20.8°) and 0.7° ± 3.2° (range, − 6.0° to 7.4°), respectively (unpaired t test, P = 0.014). The variation in the external rotation angle of the tibial component was significantly smaller in the sAP group than in the MIR group (F test, P < 0.0001), as was the number of the outliers with more than ± 5° error (Fisher's exact test, P < 0.0001).ConclusionsThe use of the sAP line as the AP reference could improve and stabilize the rotational orientation of the tibial component in UKA procedures.     

Intraoperative fluoroscopy shows better agreement and interchangeability in tibial tunnel location during single bundle anterior cruciate ligament reconstruction with postoperative three-dimensional computed tomography compared with an intraoperative image-free navigation system

BackgroundFluoroscopy and navigation systems provide an accurate and reproducible method of guiding anatomical tunnel positioning during anterior cruciate ligament reconstruction (ACLR). The aim was to evaluate the differences in tibial tunnel location assessed by both an intraoperative navigation system and fluoroscopy, validated using a one-week postoperative three-dimensional computed tomography (3DCT).MethodsThe tibial tunnel location in a consecutive series of 35 patients who received a single-bundle ACLR was evaluated by intraoperative navigation system, fluoroscopic image and compared with postoperative 3DCT position. The location to the anterior–posterior (AP) and medial–lateral (ML) direction were compared between all three methods.ResultsThe tibial tunnel locations were 46.7 ± 4.5%, 44.5 ± 1.9%, and 43.6 ± 2.4% in ML direction, and 42.8 ± 7.6%, 37.9 ± 3.8%, and 37.9 ± 3.7% in AP direction using an intraoperative navigation system, fluoroscopic image and postoperative 3DCT, respectively. Significant differences between the navigation system and fluoroscopic image (ML, P = 0.001; AP, P = 0.006), and the navigation system and 3DCT (ML, P = 0.001; AP, P < 0.001) were seen. However, there was no significant difference between fluoroscopy and 3DCT (ML, P = 0.315; AP, P = 0.999). There was a significant lack of agreement for analyses measured using a navigation system and 3DCT. Fluoroscopy and 3DCT demonstrated an acceptable agreement (ML, r_pt = − 0.21, P = 0.232; AP, r_pt = 0.04, P = 0.826).ConclusionsA tibial tunnel location assessed by intraoperative fluoroscopy shows better agreement and interchangeability with one-week postoperative 3DCT validation during single-bundle ACLR compared with an intraoperative image-free navigation system.     

Open wedge high tibial osteotomy using three-dimensional printed models: Experimental analysis using porcine bone

Background

The purpose of this study was to evaluate the usefulness of three-dimensional (3D) printed models for open wedge high tibial osteotomy (HTO) in porcine bone.

Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty

BackgroundWhile patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism.MethodsWe performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion.ResultsThere were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing.ConclusionDespite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.