Posterior Slope Angle Research Articles

Robotic-assisted total knee arthroplasty improves implant position and early functional recovery for the knee with severe varus/valgus deformity

PurposeRobotic-assisted total knee arthroplasty (r-TKA) facilitates precise bone resection and lower limb alignment, yet accuracy and functional recovery for severe varus/valgus deformity is not well-documented. The aim of study was to investigate whether r-TKA improves implant alignment in the coronal and sagittal view and early functional recovery compared to conventional TKA(c-TKA).MethodsThis comparative study included 86 patients with symptomatic knee arthritis who underwent primary TKA at our institution between 1st May and 31th November 2021. Radiological parameters evaluated included hip-knee-ankle angle (HKAA), femoral varus-valgus angle (FVVA), tibial varus-valgus angle (TVVA), posterior tibial slope angle (PTSA), femoral sagittal angle (FSA), posterior condylar offset ratio, and Insall-Salvati index. Operative time, stay length, and complications were reviewed from patient records. The hospital for special surgery (HSS), Visual Analogue Scale (VAS) and knee joint motion range were evaluated at the six-month follow-up.ResultsThe c-TKA and r-TKA groups had no significant differences in HKAA (179.73 ± 3.76°, range: 172.10-188.90° vs. 180.53 ± 2.91°, range: 173.30-188.32°, p = 0.277), FVVA (96.13 ± 2.61°, range: 90.27-101.52° vs. 96.38 ± 2.23°, range: 90.98-100.95°, p = 0.636), and TVVA (88.74 ± 2.03°, range: 83.75–92.74° vs. 89.43 ± 1.83°, range: 85.32–94.15°, p = 1.000). Outlier of mechanical alignment incidence (> 3°) was significantly lower in r-TKA compared with c-TKA, 17.50% (7/40) vs. 41.30% (19/46), (p = 0.017). PTSA of r-TKA remained significantly lower than c-TKA (p = 0.009) in mild-deformity patients. For severe varus/valgus deformity, r-TKA had a significantly lesser HKAA-outlier incidence (p = 0.025), PTSA-outlier incidence (p = 0.019), and lower PTSA (p < 0.001) compared with c-TKA. The r-TKA functional outcome was better than c-TKA regarding HSS (93.12 ± 1.97, range: 90–95, 95%CI:92.11–94.13 vs. 91.33 ± 2.50, range: 85–95, 95%CI:90.20-92.69, p = 0.036), and VAS (0.24 ± 0.44, range:0–1 vs. 0.72 ± 0.75, range:0–2, p = 0.026), knee joint flexion (118.53° ± 8.06, range: 105–130°, 95%CI:114.39-122.67° vs. 112.22 ± 8.09°, range: 100–130°, 95%CI:108.20-116.24° ,p = 0.027) for severe varus/valgus deformity.Conclusionr-TKA improved lower-limb coronal alignment, sagittal implant position, and early functional recovery for patients with severe varus/valgus deformity of the knee. r-TKA did not confer substantial advantages over c-TKA in both radiological and clinical outcomes for the mild varus/valgus deformity.

Posterior tibial slope considered as an important addition to the CPAK classification system

IntroductionCoronal Plane Alignment of the Knee (CPAK), is an informative way to classify native knee alignment types, but does not consider posterior tibial slope, an important variable in knee kinematics. We hypothesized that tibial slope would have a significant effect on knee kinematics and warrant consideration in addition to the CPAK system. MethodsWe examined 335 adult patients with osteoarthritis receiving total knee arthroplasty. We measured the lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and posterior tibial slope angle (PTS). Knees were categorized into CPAK classes and subdivided into types ‘A’ (PTS 8°) or ‘B’ (PTS >8°). We recorded pre-and-post operative knee flexion, and extension/flexion gaps in all subjects. ResultsCPAK classes VII-IX were not seen. Classes I and II comprised a plurality of all knees. One-third of all knees were type B. CPAK classes III, IV, and VI had greater type B proportions, but this was not statistically significant. Type B knees had greater flexion both pre-op (p < .001) and post-op (p = .043); type A knees had greater flexion improvement pre-to-post operatively (p = .045). Type A knees had greater medial and lateral flexion-extension gap change pre-operatively (p = .021) and (p = .027), respectively. Type B knees had greater medial-lateral gap imbalance preoperatively in both flexion and extension. Discussion/conclusionOur results suggest that there are important pre and post-operative differences in medial and lateral femorotibial gap balance between type A and B knees that require consideration for intra-operative balancing. Differences in knee flexion further solidify that PTS is an important variable that affects kinematics before and after TKA. We propose the addition of PTS types A and B to the existing CPAK classes. This is an easy and logical way to create a comprehensive classification system in both coronal and sagittal planes that captures further differences in knee kinematics.

Surgical accuracy of coronal and sagittal alignment in conventional closed-wedge high tibial osteotomy after computer-assisted surgery experience

BackgroundAlthough intraoperative navigation can improve the surgeon’s proficiency, no studies have analyzed postoperative outcomes of high tibial osteotomy (HTO) after computer-assisted surgery (CAS) experience. The present study compared the clinical and radiographic results between conventional and CAS closed-wedge (CW) HTOs after CAS experience.MethodsEach of the 50 conventional and CAS CW HTOs performed by single surgeon between 2015 and 2017 were included. The surgeon had experience of 140 cases of CAS CW HTOs before the study period. The groups were not different in terms of demographics. Clinically, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were investigated. Radiographically, the mechanical axis (MA), change in posterior tibial slope angle (PTS), and parallel angle were evaluated. The proportions of inlier groups for the postoperative MA (within valgus 2° ± 3°), change in the PTS (within ± 3°), and parallel angle (< 3°) were compared.ResultsThere were no significant differences in postoperative clinical results between the conventional and CAS groups. The MA was appropriately corrected in both groups (2.4° versus 2.9°, p = 0.317). The amount of change in PTS was significantly greater in the conventional group (−2.2° versus −0.8°, p = 0.018). The parallel angle was 5.3° in the conventional groups and 3.1° in the CAS group (p = 0.003). The proportion of inlier group was not significantly different in the postoperative MA (72% versus 78%) and change in the PTS (52% versus 66%). The proportion of inlier for the parallel angle was significantly lower in the conventional group (36% versus 60%, p = 0.027).ConclusionsThe surgical proficiency after CAS experience could cover the advantages of an intraoperative navigation in coronal adjustment, not in the sagittal adjustments in CW HTOs. A larger cohort with multiple surgeons in multiple centers would be required to identify the general trend.Study designLevel of evidence III.

Potential problem and solution of lateral plate postposition for the posterolateral tibial plateau fracture

BackgroundThere has been controversial for the treatment of the posterolateral tibial plateau fractures (PTPF). This study aimed to evaluate clinic outcomes of the lateral locking compression plate (LCP) postposition, analyze the feasibility of LCP postposition through anatomical measurement, and address the potential problems of LCP postposition through the biomechanical assessment.Methods39 patients with PTPF undergoing LCP fixation between June 2019 and June 2022 were retrospectively evaluated. All cases were divided into two group: Group A (15 cases) employed plate transverse arm postpositioning with posterolateral (PL) fracture fixation using two raft screws, while Group B (24 cases) utilized non-postpositioning with fixation by a single raft screw. Surgical duration, intraoperative blood loss, the change of lateral tibial plateau angle (LTPA), lateral tibial plateau posterior slope angle (LPSA) and fracture collapse between immediate postoperative and last follow up, range of motion (ROM), HSS knee score, and Lysholm knee score were recorded. CT measurements of the fibular head superior space and LCP transverse arm were taken in 50 healthy adult knees to assess postposition feasibility. Finally, three fracture models were established using finite element analysis: Model A with plate postposition and PL split fracture fixed by two raft screws of transverse arm, Model B with plate non-postposition and PL split fracture fixed by one raft screw, and Model C with plate non-postposition and PL split fracture fixed by one raft screw and anterior–posterior tension screws. Loadings of 250N, 500N, and 750N were applied for the analysis of the displacement degree, von Mises stress distribution.ResultsResults indicate comparable operative duration and intraoperative hemorrhage between groups. Complications were minimal in both groups. Group A demonstrated superior outcomes in terms of radiographic parameters, functional scores, and fracture collapse prevention. CT measurements revealed compatibility in 72% of healthy knees with the postpositioning technique. Finite element analysis indicated favorable biomechanical stability.ConclusionNot all patients with PTPF were applicable to the management of the plate postposition and two raft screws fixation, even though this technique exerted good biomechanical stability and achieved satisfactory clinic outcomes. When the PL fracture was fixed by only raft screw through LCP owing to various reasons, two anterior–posterior tension screws might be necessitated to maintain the fracture stability.

Computed tomography-based patient-specific cutting guides used for positioning of the femoral component of implants during unicompartmental knee arthroplasty: a cadaver study

BackgroundTo investigate whether patient-specific instrumentation (PSI) improves the femoral component positioning of implants during unicompartmental knee arthroplasty (UKA) using cadaver bone models.MethodsFifty adult cadaveric femoral bone specimens collected from February 2016–2018, were randomized to receive medial UKA with a PSI guide (n = 25) or conventional instrumentation (CI) (n = 25). Standard anteroposterior and lateral view radiographs were obtained postoperatively to assess the coronal and sagittal positioning of the femoral prostheses, respectively. The osteotomy time was recorded to assess the convenience of PSI in guiding osteotomy.ResultsOsteotomy time significantly shortened in the PSI group (3.12 ± 0.65 versus 4.33 ± 0.73 min, p < 0.001). There was a significant difference in the postoperative coronal alignment of the femoral component between the PSI and CI groups (varus/valgus angle: 1.43 ± 0.93° vs. 2.65 ± 1.50°, p = 0.001). The prevalence of outliers in coronal alignment was lower in the PSI than the CI group (2/25, 8% vs. 9/25, 36%). Sagittal posterior slope angle of the femoral component was significantly different between the two groups (8.80 ± 0.65° and 6.29 ± 1.88° in the CI and PSI groups, respectively, p < 0.001). The malalignment rate of the femoral component in the sagittal plane was 60% in the CI group, whereas no positioning deviation was observed in the PSI group.ConclusionThis study used a cadaver model to support the fact that CT-based PSI shows an advantage over CI in optimizing implant positioning for UKAs.

Clinical study on the subchondral screw compression technique assisted reduction of residual or secondary collapse of lateral tibial plateau

To explore the reduction and support effect of the subchondral screw compression technique for residual or secondary collapse of the lateral tibial plateau during operation. Between January 2020 and June 2021, 11 patients with residual or secondary collapse of the lateral tibial plateau during operation were treated with the subchondral screw compression technique. There were 6 males and 5 females, aged 52.3 years old (range, 27-64 years). The fractures were caused by traffic accident in 10 cases and falling from height in 1 case and located at the left knee in 6 cases and the right knee in 5 cases. According to Schatzker classification, there were 5 cases of type Ⅱ fractures, 4 cases of type Ⅲ fractures, and 2 cases of type Ⅴfractures. According to the three columns classification, there were 5 cases of lateral column, 4 cases of lateral column and posterior column, and 2 cases of three columns. The time from injury to operation was 4.5 days (range, 3-7 days). During the follow-up, X-ray films were obtained and the Rasmussen standard was used to evaluate the quality of fracture reduction, meanwhile fracture healing was observed. The medial proximal tibial angle (mPTA), posterior tibial slope angle (pTSA), and articular surface collapse were measured at immediate and 12 months after operation. The knee joint range of motion was evaluated at last follow-up, and the knee joint function was evaluated using the Hospital for Special Surgery (HSS) score. All operations were successfully completed, with a mean operation time of 71.4 minutes (range, 55-120 minutes), and a mean hospital stay of 8.0 days (range, 5-13 days). The incisions all healed by first intention, without complications such as infection, flap necrosis, or vascular and nerve injury. All patients were followed up 16.5 months on average (range, 12-24 months). X-ray films showed that the fracture reduction score was 14-18 (mean, 16.7) according to Rasmussen score criteria; and 5 cases were rated as excellent and 6 as good. All fractures healed clinically with a mean clinical healing time of 14.9 weeks (range, 12-16 weeks), and there was no complications such as plate or screw loosening. At 12 months after operation, the mPTA and pTSA were (87.5±1.7)° and (6.2±3.1)°, respectively; there was no significant difference when compared to the values at immediate after operation [(87.6±1.8)° and (6.5±3.1)°] ( P>0.05). The articular surface of the tibial plateaus was effectively supported, and it collapsed again by 0-1.0 mm at 12 months, with an average of 0.4 mm. At last follow-up, the knee joint range of motion was 115°-135° (mean, 126.8°) and the HSS score for knee joint function was 87-98 (mean, 93.9). Five patients underwent secondary operation to remove the internal fixator at 12-18 months after operation. The subchondral screw compression technique is helpful for the reduction of residual or secondary collapse of the lateral tibial plateau during operation, and can provide good support for osteochondral blocks.

Bone Healing and Clinical Outcome Following Medial Opening-wedge High Tibial Osteotomy Using Wedge-Shaped Cancellous Allograft.

Medial opening-wedge high tibial osteotomy (MOWHTO) is considered to be an effective treatment for symptomatic knee osteoarthritis (KOA) of isolated the medial compartment with varus alignment of the lower extremity. However, the choice of material to fill the void remains controversial. This study aims to evaluate the bone union of the osteotomy gap using a novel wedge-shaped cancellous allograft after MOWHTO and its effect on clinical outcomes. All patients who underwent MOWHTO using a novel wedge-shaped cancellous allograft combined with TomoFix locking compression plate (LCP) fixation between January 2016 and July 2020 were enrolled. The radiographic parameters including hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), femorotibial angle (FTA) and posterior tibial slope angle (PTSA) were measured between pre-operative and post-operative radiographs. Knee Society score (KSS) and range of motion (ROM) were assessed preoperatively and at last follow-up. Patients included in this study were divided into two groups according to the correction angle: small correction group (< 10°; SC group) and large correction group (≥ 10°; LC group). The modified Radiographic Union score for tibial fractures (mRUST) was used to assess the difference in bone healing between the two groups at 1, 3, 6, and 12 months postoperatively and at the final follow-up. A paired student's t test was conducted for comparison of differences of the relevant data pre-operatively and post-operatively. A total of 82 patients (88 knees) were included in this study. The HKAA, MPTA, FTA and PTSA increased from -6.4° ± 3.0°, 85.1° ± 2.6°, 180.1° ± 3.2° and 7.7° ± 4.4° preoperatively to 1.2° ± 4.3° (p < 0.001), 94.4° ± 3.3° (p < 0.001), 171.0° ± 2.8° and 11.8° ± 5.8° (p < 0.001) immediately postoperatively, respectively. However, no significant statistic difference was found in above-mentioned parameters at last follow-up compared to immediate postoperative data (p > 0.05). All patients in this study achieved good bone healing at the final follow-up and no significant differences in mRUST scores were seen between the SC group and LC group. The KSS-Knee score and KSS-Function score improved significantly from 55.4 ± 3.7 and 63.3 ± 4.6 preoperatively to 86.4 ± 2.8 (p < 0.001) and 89.6 ± 2.9 (p < 0.001) at last follow-up, respectively. Nevertheless, there was no significant difference in ROM between pre-operation and last follow-up (p > 0.05). For MOWHTO, the wedge-shaped cancellous allograft was a reliable choice for providing good bone healing and clinical outcomes.

Implant Removal After Medial Opening Wedge High Tibial Osteotomy Provides Implant-Related Pain Relief and Functional Improvement

PurposeTo (1) investigate the incidence of implant-related pain after medial opening wedge high tibial osteotomy (MOWHTO) using locking plate, (2) determine whether implant removal provides pain relief and functional improvement, and (3) evaluate bone healing and loss of correction after implant removal. Materials and MethodsBetween March 2014 and September 2017, MOWHTO was performed without bone graft. The inclusion criteria were patients who underwent implant removal after MOWHTO and were followed up for a minimum of 2 years. Patients were evaluated for implant removal one and two years after surgery. Clinical and functional evaluations were conducted to investigate implant-related pain using the visual analog scale, Lysholm score, and Tegner score. The radiographic indices measured were the gap-filling rate, weight-bearing line (WBL) ratio, hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and posterior tibial slope angle (PTSA). ResultsA total of 55 patients were enrolled. Fifty-one (92.7%) patients experienced implant-related pain prior to implant removal, with 43 and eight patients reporting mild pain and moderate pain, respectively. At one and two years after implant removal, mild pain was six (10.9%) and five (9.1%) patients, respectively. The remaining patients reported no implant-related pain. Prior to implant removal and one year after implant removal, the Lysholm score improved from 77.0±5.6 to 86.8±5.7 (P<0.001), and the Tegner score improved from 3.3±1.2 to 3.9±1.3 (P<0.001). The mean gap-filling rate was 84.4%±9.6% at implant removal, and it significantly increased to 93.7%±5.4% and 97.4%±2.6% at one and two years after implant removal, respectively (P<0.001) For the WBL ratio, HKAA, MPTA, and PTSA, no statistical differences were found after implant removal. ConclusionThe incidence of implant-related pain after MOWHTO using medial proximal tibial locking plate was high. Implant removal provides pain relief and functional improvement (met minimal clinically important differences). Even after implant removal, bone healing progressed gradually without a loss of correction in all patients.

Postoperative quadriceps weakness and male sex are risk factors for patellofemoral articular cartilage lesions after anatomical anterior cruciate ligament reconstruction

PurposePatellofemoral (PF) compartment cartilage lesions are a frequent problem after anterior cruciate ligament (ACL) reconstruction. This study aimed to determine the factors that influence PF cartilage lesions after anatomical ACL reconstruction.MethodsThis study enrolled a total of 114 patients who did not manifest PF compartment cartilage lesions during anatomical ACL reconstruction and underwent second-look arthroscopy 18 months postoperatively. Arthroscopy using the International Cartilage Repair Society (ICRS) classification was used to assess cartilage lesions. The correlation between surgical findings, radiographic factors, and clinical factors and change of ICRS grade was analysed. Multivariate regression analysis was conducted to reveal the independent risk factors for PF cartilage lesions among patients’ demographic data and parameters that correlated with the change of ICRS grade in the correlation analyses.ResultsICRS grade changes in PF cartilage were significantly correlated with age, sex, quadriceps strength at 1 year postoperatively, hamstrings strength at pre- and 1 year postoperatively, and single leg hop test at 1 year postoperatively. However, no significant correlation was found between the time between injury and surgery, posterior tibial slope angle, pre- and postoperative Tegner activity scale, graft type, initial graft tension, meniscus injury, meniscus injury treatment, pre- and postoperative range of motion, anteroposterior laxity and preoperative quadriceps strength, and the change in ICRS grade. Multivariate regression analysis revealed male (P = 0.019) and quadriceps strength weakness at 1 year postoperatively (P = 0.009) as independent risk factors for PF cartilage lesions.ConclusionsQuadriceps strength weakness 1 year after ACL reconstruction and males were correlated with a new PF cartilage lesion after anatomical ACL reconstruction, with no significant correlation between bone-patellar tendon-bone autograft, initial graft tension, or extension deficit and new PF cartilage lesion. Rehabilitation that focuses on quadriceps strength after ACL reconstruction is recommended to prevent new PF cartilage lesions.Level of evidenceLevel IV.

Medial open-wedge high tibial osteotomy for the treatment of degenerative varus knee osteoarthritis in geriatric patients: a retrospective study

HTO has proven to be a cost-effective surgical procedure in the treatment of KOA, but few investigations have studied radiological changes and clinical effectiveness of OWHTO in geriatric patients. 76 patients were recruited in this retrospective study. According to the age, patients were divided into two groups (≤ 60, Group “Young”; > 60, Group “Geriatric”). Demographic data, radiological imaging and postoperative complications were analyzed. Kellgren–Lawrence grade (K–L), weight-bearing line ratio (WBLR); posterior tibial slope angle (PTS); American knee score (AKS); Western Ontario and McMaster Universities Arthritis Index (WOMAC) and visual analog scale (VAS) were introduced to estimate the clinical outcome of OWHTO. There were 18 male and 58 female patients in the present study with a mean age of 58.5 ± 9.2 years (ranges from 40 to 82 years); the average age was 51.4 ± 4.1 years and 67.3 ± 4.9 years for group Y and G respectively, 44.7% and 31.5% patients were older than 60 and 65 years. BMI for the 76 patients was 26.6 ± 3.2 kg/m2, and geriatric patients were more likely accompanied by one or more comorbidities (70.6 vs. 45.2%). There were 34 and 42 patients in group Geriatric and group Young respectively, and no significant difference of MPTA, WBLR, PTS and WOMAC, VAS, AKS and ROM between the two group (P > 0.05) were found. After more than a two-year follow-up period, postoperative WBLR, AKS, WOMAC and VAS were much more desired than preoperative, and no significant difference of these variables between the young and geriatric group (P > 0.05), however, elderly patients were more likely to suffer from a longer bone union time. OWHTO can avoid geriatric patients from undergoing secondary knee surgery in the short term, however the survival rate of OWHTO in geriatric patients should be ultimately clarified by different studies.

Medial opening-wedge high tibial osteotomy with microfracture in treatment of varus medial compartmental knee osteoarthritis: clinical outcomes and second-look arthroscopic results.

Objective: This study aimed to investigate the clinical outcomes of medial opening high tibial osteotomy (MOWHTO) combined with arthroscopic microfracture in the treatment of varus medial compartmental knee osteoarthritis and to assess cartilage regeneration using second-look arthroscopy. Methods: This study involved 86 patients (86 knees) who underwent MOWHTO and microfracture from August 2016 to August 2020, including 15 men and 71 women with an average age of 55.3 ± 7.6years (range, 42-71years). The patients underwent a second-look arthroscopy to evaluate the status of cartilage regeneration at the time of plate removal, an average of 2years after the initial osteotomy. Clinical and radiological examinations were performed preoperatively and at the final follow-up visit. The radiologic evaluation included the weight-bearing line ratio (WBL ratio), mechanical femorotibial angle (FTA), medial proximal tibial angle (MPTA), posterior tibial slope angle (PTS) and Kellgren-Lawrence (KL) grade. Clinical outcomes were assessed using the Knee Society score (KSS) and International Knee Documentation Committee (IKDC) scores. Arthroscopic findings were assessed by macroscopic evaluation of cartilage repair according to the International Cartilage Repair Society (ICRS) grading system. Results: The mean KSS and IKDC scores significantly improved at the final follow-up compared to the scores obtained preoperatively (p < 0.05). At the time of plate removal, a second-look arthroscopic examination showed that the ICRS grade of the medial femoral condyle was as follows: grade I -11 cases, grade II -56, grade III-12, and grade IV-7, and cartilage regeneration was seen in 85% of knees (73/86). The ICRS grade of medial tibial plateau was grade I-12 cases, grade II-44, grade III-22, and grade IV-8, and cartilage regeneration was seen in 63% of knees (54/86). Significant differences were observed between cartilage regeneration and clinical outcomes (p < 0.05). Clinical results were better in the good cartilage regeneration group (grades I and II) than were in the poor cartilage regeneration group (grades III and IV). Conclusion: MOWHTO combined with arthroscopic microfracture can effectively improve clinical outcomes in the treatment of varus medial compartmental knee osteoarthritis. Cartilage regeneration can be promoted by correcting varus deformities, which affect clinical outcomes.

A Combined Surgical Approach for Recurrent Patellar Dislocation in Adolescents With Patella Alta and Increased Tibial Tuberosity-Trochlear Groove Distance: Improved Clinical Outcomes but Decreased Posterior Tibial Slopes in Skeletally Immature Patients at Minimum 4-Year Follow-Up

Purpose(1) To report the clinical and radiological outcomes of a surgical technique combining anatomic medial patellofemoral ligament (MPFL) reconstruction and tibia tuberosity transfer in adolescents with patella alta and elevated tibial tuberosity-trochlear groove (TT-TG) distance, in the treatment of recurrent patellar dislocation (RPD); (2) To investigate the potential risks of growth arrest or developmental deformities associated with this combined technique. MethodsMedical records of patients underwent the combined surgery were reviewed from 2015 to 2019. This study included adolescents aged between 14 and 18 years with a Caton-Deschamps index (CDI) greater than 1.30 and TT-TG distance greater than 20mm, with a minimum follow-up of 4 years. Radiological examinations including lateral views and full-length posteroanterior standing radiographs were investigated to assess patella height by CDI, posterior tibia slope (PTS) angle, side-to-side difference (SSD) in bone length, and lower extremity alignment by hip-knee-ankle (HKA) angle; CT-scans and MRI profiles were investigated to evaluate TT-TG distance and staging of growth plate closure. Other evaluations included preoperative and postoperative physical examination, Kujala score, and Tegner activity score. The patients were stratified into 3 subgroups according to a MRI-based staging system of the growth plate closure, and each outcomes were analyzed. A cohort-specific minimal clinically important difference (MCID) estimation was performed using standard error of measurement. ResultsThe average age at the time of surgery was 16.1 years (range, 14.1-17.8). The average follow-up was 5.6 years (range, 4.0-7.6). No recurrent dislocation occurred, no clinically significant deformity or axis deviation was encountered. Postoperative patellar height by CDI was 1.00±0.11 (range, 0.81-1.15). No significant differences were found in pre- and postoperative HKA angle and SSD in femur/tibia length among all subgroups. A significantly decreased PTS angle was found in patients with open growth plates, from 10.2±1.7° preoperatively to 8.1±1.0° postoperatively (P=.015). The Kujala score and Tegner score both significantly improved, from 65.5±13.9 preoperatively to 90.4±7.2 postoperatively in Kujala score (P <0.001), and from 4.0±1.1 preoperatively to 4.7±1.3 postoperatively in Tegner score (P <0.001). Of the whole cohort, 63.1%, 100%, 47.1% and 94.1% patients achieved the MCID for PTS angle, CDI, Tegner score, and Kujala score respectively. ConclusionThis combined technique is safe and effective in treating RPD in skeletally mature adolescents with concurrent patella alta (CDI > 1.30) and TT-TG distance > 20mm, permitting patients to have improved knee function and low complication rates. Nonetheless, patients with open growth plates demonstrated a decrease in PTS, which might predispose the knee to recurvatum and osteoarthritis in the long-term. Study DesignRetrospective therapeutic case series; level of evidence, Ⅳ.

How to Choose the Appropriate Posterior Slope Angle Can Lead to Good Knee Joint Function Recovery in Total Knee Arthroplasty?

In this study, we aim to examine the effects of osteotomy under varying posterior slope angles on knee joint function recovery following knee arthroplasty. We conducted a retrospective analysis from September 2015 to September 2018 on 240 patients who underwent knee arthroplasty three years previously. The study participants were categorized based on changes in the angle of the posterior slope before and after surgery: Group 1, > 5°; Group 2, 3°-5°; Group 3, 0°-3°; Group 4, -3°-0°; Group 5, < -3°. All participants were affected with knee osteoarthritis. The Knee Society Clinical Rating System (KSS) knee function score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) knee function score, Visual Analogue Scale (VAS) pain score, and postoperative complications were measured 3 years after surgery. The level of pain experienced by the patients decreased significantly than before, with pain scores ranging from 1.0-3.0, and there was a statistical difference between groups (H = 93.400, P <0.001). The KSS score increased, with group 5 having the lowest median score of 78.0 and group 2 having the highest median score of 97.0, and there was a statistical difference between groups (H = 164.460, P < 0.001). The WOMAC score was reduced, with the median score being 24.0, 11.0, 14.0, 20.0, and 26.0, in the five groups, respectively. Group 5 had the highest score, while Group 2 had the lowest score, and there was a statistically significant difference between groups (H = 164.223, P < 0.001). No symptoms such as periprosthetic femoral fracture, prosthetic loosening, or pad wear were detected in patients postoperatively. Osteotomy at various posterior slope angles in total knee arthroplasty impacts postoperative knee function rehabilitation. An excessive increase or decrease in angle can have an impact on the postoperative recovery of knee function.

Study on application of posterior tibial slope angle in anterior cruciate ligament

Posterior tibial slope angle (PTSA) is a risk factor for anterior cruciate ligament (ACL) injury and has attracted a lot of attention, but its mechanism of action and diagnosis are still not systematically studied in the field of sports medicine. In this paper, we believe that PTSA should be measured by full-length lower extremity films and combined with multiple imaging data for comprehensive assessment to reduce errors. A large PTSA may increases risk of anterior cruciate ligament injury, so patients with more than 12 degrees of PTSA should be treated by preserving meniscus as much as possible during ACL reconstruction and combining with tibial osteotomy if necessary, which could effectively prevent risk of ligament re-injury. At the same time, gait analysis has an important reference value for preoperative pathogenic pattern and postoperative rehabilitation function, so the author believes that it will have a guiding significance for the development of individualized rehabilitation strategy based on PTSA, in order to achieve the best treatment effect.

Determination of Posterior Tibial Slope Changes After Tibial Plateau Fracture Fixation: A Retrospective Case Series.

A tibial plateau fracture is an intra-articular fracture that affects the function and stability of the knee joint and requires careful evaluation and pre-operative planning. We determined the posterior tibial slope changes after tibial plateau fracture stabilization, aiming to help improve surgical success in maintaining the lower limb's natural axis. This retrospective case series involved all Golestan and Imam Khomeini hospital patients (Ahvaz, Iran) with Schatzker type IV-VI tibial plateau fractures from April 1, 2017, to March 30, 2020, who underwent surgical fixation. Data on the age, gender, body mass index (BMI), surgical approach, posterior tibial slope angle in the injured and healthy knees, pain, and knee joint instability were collected. We analyzed the data using SPSS version 22 and considered a significance level of P < 0.05. Among the 31 study participants, 24 (77.4%) were males. The mean age of the patients was 39.81 ± 14.41 years (21-78), with a mean BMI of 25.4 ± 2.7 (20.3-31.2) kg/m2 and hospitalization duration of 5.8 ± 9.3 days (3-29). Most patients had type VI fractures (48.3%). The posterior tibial slope angle shared no relation with age, gender, BMI, or surgical approach (P > 0.05). After tibial plateau fracture fixation, the posterior tibial slope angle significantly increased in the injured knee compared with the healthy knee (P < 0.05). Six months after the operation, the angle of the injured knee decreased but remained higher than that of the healthy knee (P > 0.05). The tibial slope's posterior column collapses more than its anterior column over time, reducing the posterior tibial slope angle. Therefore, the correct reduction of the tibial plateau's posterior slope is more important.

Anatomical Variations in the Posterior Tibial Slope in the North Indian Population: A Hospital-Based Study.

The measurement of the posterior tibial slope (PTS) angle is crucial for various knee surgeries such as total knee replacement, high tibial osteotomy, and anterior cruciate ligament reconstruction. This hospital-based study aimed to determine the average PTS angle in the knee joints of the North Indian population and provided valuable data to aid knee surgeries in this region. An analysis of 200 plain X-ray films, specifically the true lateral view of both knees in 20-degree flexion, was conducted on participants who exhibited skeletal maturity with no arthritis, tumours, or previous knee surgeries. The PTS measurements were performed manually. The data were analyzed statistically by matching them with variables such as gender, age, laterality, and body mass index (BMI). The study revealed the following findings for the posterior tibial slope in a section of the North Indian population: there was no significant laterality difference (right knee: 12.76±2.35°, left knee: 12.55±2.46°); no notable sexual dimorphism (males: right knee - 12.79±2.65°, left knee - 12.25±2.65°, females: right knee - 12.73±2.11°, left knee - 12.77±2.30°). However, as age advanced, there were significant differences observed (PTS: 14.27±1.28° and 13.84±1.80° in the 18-40 years age group, 11.36±1.76° and 11.31±1.97° in the 41-60 years age group, 10.32±2.82° and 10.56±3.04° in the >60 years age group for the right and left knee, respectively). No significant correlation was found with BMI (PTS: 13.12±3.13° and 12.59±3.14° for BMI <25, 12.88±2.15° and 12.80±2.34° for BMI 25-30, 12.00±2.09° and 11.66±2.99° for BMI >30 in the right and left knee, respectively). The study demonstrated significant variations in the posterior tibial slope based on age, emphasizing the need for individualized treatment in knee surgeries. The research provided valuable insights into normal PTS values specific to the North Indian population, offering regional data to inform knee surgery procedures.

Poster 318: CHANGE IN POSTERIOR TIBIAL SLOPE FOLLOWING DISPLACED PEDIATRIC TIBIAL TUBERCLE FRACTURES: A POTENTIAL MODEL FOR GROWTH MODULATION IN THE ACL DEFICIENT KNEE

Objectives: Increased posterior tibial slope angle (PTSA) increases the risk for anterior cruciate ligament (ACL) tear and ACL graft failure. Proximal tibial slope changing osteotomies are employed in the adult population; growth modulation procedures may present a treatment opportunity in the skeletally immature. This procedure has not been described in the context of ACL injuries, and the rate at which posterior tibial slope could be corrected is unknown. Our purpose was to quantify the rate of change in PTSA following operatively treated displaced tibial tubercle fractures in skeletally immature patients, and to determine how this rate is affected by skeletal age. We hypothesized that there would be a progressive loss of posterior tibial slope after injury, and that rate of change in PTSA would be highest during peak growth velocity Methods: We retrospectively reviewed skeletally immature patients with tibial tubercle fractures treated with ORIF. We measured posterior tibial slope angle (PTSA) at ˜3-, 6-, 12-months, and further postoperative time points if available. All subjects had a minimum of 6-months follow up. Bone age at the time of injury was determined. Negative PTSA was indicative of posteriorly directed slope, positive PTSA indicated anterior slope. Linear regression analysis was used to evaluate rate of change in PTSA (ΔPTSA) for individual patients and total cohort trend. Patient regression coefficients were averaged into bone age cohorts. The unit of analysis was the knee. Results: Twenty-two patients with 23 knees were included. 86% of patients were male. Average chronologic and bone age was 14 years at time of injury. Average follow-up was 17 months (range 6 to 52 months). Patients had a mean PTSA of -12˚ ± 2.4˚ at the time of injury. The overall mean ΔPTSA for the cohort was 0.30˚ ± 0.31˚ per month (range -0.27˚ to 0.97˚ per month). Linear regression revealed a significant relationship between months post-fixation and PTSA, demonstrating a ΔPTSA of +0.31˚ per month (CI 95% (0.24, 0.38); p&lt;.001) (Figure 1). The highest average ΔPTSA was seen at 14-years (0.58˚ ± 0.44˚ per month). The average overall absolute change in PTSA from injury to final follow-up was +4.1˚ (range -3.4˚ to 21˚) (Figure 2). Conclusions: Our data suggest progressively more anterior slope following ORIF. The greatest rate of change in PTSA corresponded with peak growth velocity. These findings may serve as a model for predicting the effect of anterior proximal tibia epiphysiodesis on tibial slope in ACL surgery.

Comparison of outcomes of mixed unicompartmental knee arthroplasty and total knee arthroplasty in the treatment of medial osteoarthritis of the knee

To evaluate outcomes of mixed unicompartmental knee arthroplasty(UKA) and total knee arthroplasty(TKA) in the treatment of medial osteoarthritis(OA) of the knee. Retrospective analysis of 156 patients, 44 males and 112 females, aged from 50 to 75 years old with an average of(58.76±4.97) years old, who underwent knee arthroplasty from October 2017 to October 2019. The patients were divided into two groups:81 cases(81 knees) underwent TKA, including 23 males and 58 females, aged from 51 to 75 years old with an average of (58.60±5.01) years old, and 75 case (75 knees) underwent UKA with mixed phase 3 Oxford, including 21 males and 54 females, aged from 50 to 72 years old with an average of (58.92±4.95) years old. The two groups were compared regarding to the clinical outcomes, assessed using surgical information and complications, American Knee Society score(AKSS) clinical score and functional score. Radiographs were assessed using hip-knee-ankle angle(HKA), tibial component valgus/varus angle(TCVA), tibial component posterior slope angle(TCPSA), femoral component valgus/varus angle(FCVA), femoral component posterior slope angle(FCPSA), looking for bearing dislocation, prosthesis loosening, progression of OA in lateral compartment. Intraoperative bleeding, operative time and hospital days were significantly better in the UKA group than in the TKA group (P<0.05), and there were no postoperative complications in either group. Patients in both groups were enrolled with an average follow-up time of (38.01±8.90) months, ranged from 24 to 54 months. AKSS functional, AKSS clinical, HKA in both groups significantly improved at the final follow-up compared with those before operation. At the final follow-up, the UKA group was significantly better than the TKA group in AKSS functional and AKSS clinical, whereas HKA in the TKA group was better. At the final follow-up. TCVA and FCVA between the two groups were not significantly different, while TCPSA and FCPSA in the UKA group were significantly greater than the TKA group. No signs of progression of OA to the lateral compartment were observed. Mixed phase 3 Oxford UKA in medial unicompartmental knee osteoarthritis was considerably better than TKA for less blood loss, shorter operation time, shorter hospital stay, rapid postoperative recovery, helping achieve satisfactory function, provided satisfactory outcome.

Arthroscopic-assisted reduction and internal fixation for complex tibial plateau fracture: radiographic and clinical outcomes with 2- to 15-year follow-up

BackgroundTo investigate the radiologic and prognostic outcomes after using arthroscopic-assisted reduction and internal fixation (ARIF) in complex tibial plateau fractures with mid- to long-term follow-up.MethodsThis retrospective study reviewed complex tibial plateau fractures that underwent ARIF from 1999 to 2019. Radiologic outcomes, including tibial plateau angle (TPA), posterior slope angle (PSA), Kellgren–Lawrence classification and Rasmussen radiologic assessment, were measured and evaluated. The prognosis and complications were assessed by the Rasmussen clinical assessment with a minimum follow-up of 2 years.ResultsNinety-two consecutive patients (mean age: 46.9 years) with a mean follow-up of 74.8 months (24–180) were included in our series. Using AO classification, there were 20 type C1 fractures, 21 type C2 fractures, and 51 type C3 fractures. All the fractures achieved solid union. TPA was maintained well on average at the last follow-up and showed no significant difference compared to postoperatively (p = 0.208). In the sagittal plane, the mean PSA increased from 9.3 ± 2.9° to 9.6 ± 3.1° (p = 0.092). A statistically significant increase in PSA was also noted in the C3 group (p = 0.044). Superficial or deep infection was noted in 4 cases (4.3%), and total knee arthroplasty (TKA) was performed in 2 cases (2.2%) due to grade 4 osteoarthritis (OA). Ninety (97.8%) and 89 (96.7%) patients had good or excellent results in the Rasmussen radiologic assessment and Rasmussen clinical assessment, respectively.ConclusionsThe complex tibial plateau fracture could be treated successfully using arthroscopy-assisted reduction and internal fixation. Most patients achieve excellent and good clinical outcomes with low complication rates. In our experience, a higher incidence of increased slope was noted, especially in type C3 fractures. Reduction of the posterior fragment should be done cautiously during the operation.Levels of evidenceLevel III.

Artificial intelligence-based detection of posterior tibial slope on X-ray images of unicompartmental knee arthroplasty patients

ObjectiveThis paper aims to improve the assessment of the outcomes of unicompartmental knee arthroplasty (UKA) from the angle of posterior tibial slope (PTS) on X-Ray images, using the artificial intelligence (AI) tool of RetinaNet. MethodsFirstly, RetinaNet was trained and tested on patients who underwent unilateral knee replacement surgery in our hospital due to osteoarthritis in the medial compartment of either their left or right knee between July 2018 and July 2022. The trained network was applied to detect the region of interest (ROI) on the pre- and postoperative X-ray images of each subject. Next, the subjects were divided into three groups according to the PTS changes measured by the trained RetinaNet. Furthermore, the surgical effect of UKA was evaluated from multiple angles, including pre- and postoperative PTSs, knee joint mobility (KJM) values, the Hospital for Special Surgery (HSS) scores, as well as the Joint Replacement Forgetting Index (JRFI). ResultsAfter training, the RetinaNet achieved an astounding accuracy level, with the Cronbach's alpha value 0.864 (95%CI 0.762–0.915). There significant differences were found between Group II and Group I (P = 0.017) and Group III and Group I (P = 0.032); in terms of JRFI, Group II had a significantly better than Group I (P = 0.011) and Group III (P = 0.037). ConclusionsThe trained RetinaNet is suitable for assisting with PTS measurements in X-ray images; the PTS variation through UKA should be controlled within 2° to ensure the best possible surgical effect.