The 45° and 60° of sagittal femoral tunnel placement in anterior cruciate ligament reconstruction provide similar knee stability.

PURPOSE: The aim of the present study was to compare 45° and 60° of sagittal femoral tunnel angles in terms of anterior tibial translation (ATT), valgus angle and graft in situ force following anterior cruciate ligament reconstruction (ACLR). METHODS: Ten porcine knees were subjected to the following loading conditions: (1) 89 N anterior tibial load at 35° (full extension), 60° and 90° of knee flexion and (2) 5 N m valgus tibial moment at 35° and 45° of knee flexion. ATT and graft in situ force of the intact anterior cruciate ligament (ACL) and ACLR were collected using a robotic universal force/moment sensor (UFS) testing system for (1) ACL intact, (2) ACL-deficient (ACLD) and (3) two different ACLR using different sagittal femoral tunnel angles (coronal 45°/sagittal 45° and coronal 45°/sagittal 60°). RESULTS: During the anterior tibial load, the femoral tunnel angle of ACLR knees at coronal 45°/sagittal 45° and 60° had significantly higher ATT than that of the ACL-intact knees at 60° of knee flexion (p < 0.05). The femoral tunnel angle of ACLR knees at coronal 45°/sagittal 60° had significantly lower graft in situ force than that of the ACL-intact knees at 60° and 90° of knee flexion (p < 0.05). During the valgus tibial moment, the femoral tunnel angle of ACLR knees at coronal 45°/sagittal 45° and 60° had significantly lower graft in situ force than that of the ACL-intact knees at all knee flexions (p < 0.05). CONCLUSIONS: The femoral tunnel angle of ACLR knees at coronal 45°/sagittal 45° provided similar ATT, valgus angle and graft in situ force to that of ACLR knees at coronal 45°/sagittal 60°. Therefore, both femoral tunnel angles could be used in ACLR, as the sagittal femoral tunnel angle does not appear to be relevant in post-operative knee stability. LEVEL OF EVIDENCE: Not applicable.

Optimal intersurface stability for unicompartmental femoral component design with two pegs placed on the distal resection surface: 5 mm peg length increment and 10° peg inclination.

PURPOSE: The present study aimed to identify the optimal design of the unicompartmental femoral component through parameter analysis and stability evaluation. METHODS: A finite element (FE) analysis was applied to analyse and adjust the parameter combinations of the anterior tilt angle of the posterior condyle resection surface, the position of the peg, the length of the peg and the inclination angle of the peg, resulting in 10 different FE models. Setting three knee flexion angles of 8.4° (maximum load state during walking), 40° (maximum load state during stair climbing) and 90° (maximum load state during squatting exercise), quantitatively analysing the micromotion values of the bone-prosthesis interface and defining a weighted scoring formula to evaluate the stability of different FE models. The validity of the FE analysis was verified using the Digital Image Correlation (DIC) device. RESULTS: The errors between the FE analysis and the DIC test at three flexion angles were 5.6%, 1.7% and 11.1%. The 10 different femoral component design models were measured separately. The FE analysis demonstrated that the design with a 0° anterior tilt angle of the posterior condyle resection surface, both pegs placed on the distal resection surface, lengthened 5 mm pegs and a 10° peg inclination angle provided the best stability. CONCLUSION: The current study proposed a method for evaluating the stability of the femoral component design. The optimal intersurface stability design of the unicompartmental femoral component was achieved with two pegs placed on the distal resection surface, a 5-mm peg length increment and a 10° peg inclination. These results might provide a reference for the selection of unicompartmental femoral components in clinical practice and therefore improve the survival rate of future unicompartmental knee arthroplasty. LEVEL OF EVIDENCE: Level III.

Perioperative Intravenous Dexamethasone Significantly Reduces Postoperative Opioid Requirement and Nausea After Unilateral Elective Hip Arthroscopy: A Randomized Double-blinded Placebo-controlled Trial.

BACKGROUND: Previous studies have shown that dexamethasone has a positive effect on postoperative pain control, opioid consumption, nausea, and vomiting and length of hospital stay after arthroplasty surgery. PURPOSE/HYPOTHESIS: The purpose of this study was to assess whether adding perioperative dexamethasone to our current pain regimen after hip arthroscopy is more effective than a placebo. It was hypothesized that dexamethasone would reduce postoperative pain, reduce opioid consumption, improve subjective pain and nausea scores, and reduce the number of vomiting events. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 50 patients requiring unilateral elective hip arthroscopy were randomized to receive intravenous dexamethasone immediately before induction of anesthesia and at 8 am on the first postoperative day (2 ×12 mg) or a placebo (sodium chloride 0.9%). The patient, the surgeons, the treating anesthesiologist, and the involved nursing and physical therapy personnel were blinded to group assignment. The primary outcome was postoperative pain, and secondary outcomes were opioid consumption and nausea scores-assessed using a translated revised version of the American Pain Society Patient Outcome Questionnaire 6 hours postoperatively and on days 1 and 2-and vomiting events. A clinical follow-up was performed 12 weeks postoperatively to assess adverse events. RESULTS: The mean age at inclusion was 29 years in both groups. Postoperative pain levels did not differ significantly in most instances. Opioid requirements during the hospitalization in the dexamethasone group were significantly lower than those in the placebo group (31.96 ± 20.56 mg vs 51.43 ± 38 mg; P = .014). Significantly fewer vomiting events were noted in the dexamethasone group (0.15 ± 0.59 vs 0.65 ± 0.91; P = .034). Descriptive data and surgical parameters did not differ significantly. CONCLUSION: Perioperative intravenous dexamethasone significantly reduced postoperative opioid consumption by 40% without compromising pain level and safety, as no corticosteroid-related side effects were observed. Dexamethasone may be a valuable adjuvant to a multimodal systemic pain regimen after hip arthroscopy. REGISTRATION: NCT04610398 (ClinicalTrials.gov identifier).

Influence of offset on osseointegration in cementless total hip arthroplasty: A finite element study.

Early aseptic loosening is caused by deficient osteointegration of the femoral stem due to increased micromotions and represents a common mode of failure in uncemented total hip arthroplasty (THA). This study hypothesized that a higher femoral offset, a smaller stem size and obesity increase femoral micromotion, potentially resulting in early aseptic loosening. A finite element analysis was conducted based on computed tomography segmented model of four patients who received a THA with a triple-tapered straight stem (Size 1, 3, 6). The influence of femoral stem offset (short neck, standard, lateral), head length (S to XXL), femoral anteversion and obesity during daily activities of fast walking and stair climbing was analyzed. The micromotions for the femoral stem zones were compared to a threshold representing a value above which only partial osseointegration is expected. The minimum femoral offset configuration compared to the maximum offset configuration (short neck stem, S head vs. lateral stem, XXL head) leads to a relative mean micromotion increase of 24% for the upper stem zone. Increasing the body weight (body mass index 30-35 kg/m2) increases the micromotion by 20% for all stem zones. The obese population recorded threshold-exceeding micromotions for stem sizes 1 and 3 for all offset configurations during stair climbing. Higher femoral offset, a smaller stem size, and higher loading due to obesity lead to an increase in micromotion between the prosthesis and proximal femur and represent a risk configuration for impaired osseointegration of a triple-tapered straight stem, especially when these three factors are present simultaneously.

High femoral offset as a risk factor for aseptic femoral component loosening in cementless primary total hip arthroplasty.

PURPOSE: Lateralized stems in primary cementless total hip arthroplasty (THA) showed to be associated with aseptic femoral loosening. However, femoral head length also affects femoral offset but was not considered so far. This study analyzed the impact of high femoral offset (hFO) combinations, formed by lateralized stems or large femoral head lengths, on aseptic femoral component loosening. METHODS: Retrospective cohort study was performed including all patients that underwent primary cementless THA at our institution between July 2004 and December 2016. Patients were screened for aseptic femoral component loosening and grouped in aseptic loosening (AL) and non-aseptic loosening (nAL) group. Medical records were screened; implant details were noted and classified in hFO and standard femoral offset (sFO) combinations. Supposed risk factors for aseptic loosening were analyzed. RESULTS: Two thousand four hundred fifty-nine THA could be included, containing 14 THA (0.6%) with aseptic femoral component loosening. The AL group contained 11 hFO combinations (78.6%), whereas in the nAL group, 1315 hFO combinations (53.8%) were used. Subgroup analysis showed significant difference between two groups for hFO combinations (p = 0.014), age (p = 0.002), NSAR (p = 0.001), and bilateral THA on same day (p = 0.001). The multiple logistic regression analysis showed that hFO combination was the only variable for increased probability of aseptic loosening (OR, 3.7; p = 0.04). CONCLUSION: High femoral offset combinations, formed by lateralized stems or large femoral head lengths in our collective of standard straight stems implanted by an anterior approach, show a 3.7-fold increased probability for aseptic femoral component loosening. Adjustment of the postoperative protocol may be considered in these cases to ensure proper stem ingrowth.

Race and Gender Differences in Anterior Cruciate Ligament Femoral Footprint Location and Orientation: A 3D-MRI Study.

OBJECTIVE: The femoral tunnel position is crucial to anatomic single-bundle anterior cruciate ligament (ACL) reconstruction, but the ideal femoral footprint position are mostly based on small-sized cadaveric studies and elderly patients with a single ethnic background. This study aimed to identify potential race- or gender-specific differences in the ACL femoral footprint location and ACL orientation, determine the correlation between the ACL orientation and the femoral footprint location. METHODS: Magnetic resonance images (MRIs) of 90 Caucasian participants and 90 matched Chinese subjects were used for reconstruction of three-dimensional (3D) femur and tibial models. ACL footprints were sketched by several experienced orthopedic surgeons on the MRI photographs. The anatomical coordinate system was applied to reflect the ACL footprint location and orientation of scanned samples. The femoral ACL footprint locations were represented by their distance from the origin in the anteroposterior (A/P) and distal-proximal (D/P) directions. The orientation of the ACL was described with the sagittal, coronal and transverse deviation angles. The ACL orientation and femoral footprint position were compared by the two-sided t-test. Multiple regression analysis was used to study the correlation between the orientation and femoral footprint position. RESULTS: The average femur footprint A/P position was -6.6 ± 1.6 mm in the Chinese group and -5.1 ± 2.3 mm in the Caucasian group, (p < 0.001). The average femur footprint D/P position was -2.8 ± 2.4 mm in Chinese and - 3.9 ± 2.0 mm in Caucasians, (p = 0.001). The Chinese group had a mean difference of a 1.5 mm (6.1%) more posterior and 1.1 mm (5.3%) more proximal in the position from the flexion-extension axis (FEA). And the males have a sagittal plane elevation about 4-5° higher than females in both racial groups. Furthermore, for every 1% (0.40 mm) increase in A/P and D/P values, the sagittal angle decreased by about 0.12° and 0.24°, respectively; the coronal angle decreased by about 0.10° and 0.30°, respectively. For every 1% (0.40 mm) increase in D/P value, the transverse angle increased by about 0.14°. CONCLUSION: The significant race- and gender-specific differences in the femoral footprint and orientation of the ACL should be taken in consideration during anatomic single-bundle ACL reconstruction. Furthermore, the quantitative relationship between the ACL orientation and the footprint location might provide some reference for surgeons to develop a surgical strategy in ACL single-bundle reconstruction and revision.

The effect of experimentally induced gluteal muscle weakness on joint kinematics, reaction forces, and dynamic balance performance during deep bilateral squats.

Squatting is a common daily activity and fundamental exercise in resistance training and closed kinetic chain programs. The aim of this study was to investigate the effects of an experimentally induced weakness of the gluteal muscles on joint kinematics, reactions forces (JRFs), and dynamic balance performance during deep bilateral squats in healthy young adults. Ten healthy adults received sequential blocks of (1) branch of the superior gluteal nerve to the tensor fasciae latae (SGNtfl) muscle, (2) superior gluteal nerve (SGN), and (3) inferior gluteal nerve (IGN) on the dominant right leg. At the control condition and following each block, the participants were instructed to perform deep bilateral squats standing on two force plates. Hip, knee, ankle, and pelvis kinematics did not differ significantly following iatrogenic weakness of gluteal muscles. The most important finding was the significant differences in JRFs following SGN and IGN block, with the affected hip, patellofemoral, and ankle joint demonstrating lower JRFs, whereas the contralateral joints demonstrated significantly higher JRFs, especially the patellofemoral joint which demonstrated an average maximum difference of 1.43 x body weight compared with the control condition. When performing a deep bilateral leg squat under SGN and IGN block, the subjects demonstrated an increased center of pressure (CoP) range and standard deviation (SD) in mediolateral compared with the control condition. These results imply that squat performance changes significantly following weakness of gluteal muscles and should be considered when assessing and training athletes or patients with these injuries.

Combined Anteversion Threshold to Avoid Anterior Dislocation in Primary Total Hip Arthroplasty Performed Through the Direct Anterior Approach.

BACKGROUND: Component malposition in total hip arthroplasty (THA) can lead to dislocation, early implant failure, and revision surgery. As the surgical approach might affect the targeted combined anteversion (CA) of THA components, the present study aimed to evaluate the optimal CA threshold to avoid anterior dislocation in primary THA performed through a direct anterior approach (DAA). METHODS: A total of 1,176 THAs in 1,147 consecutive patients (men: 593, women: 554) who had an average age of 63 years (range, 24 to 91) and a mean body mass index of 29 (range, 15 to 48) were identified. Medical records were reviewed for dislocation, whereas postoperative radiographs were assessed to measure the acetabular inclination and CA using a previously validated radiographic method. RESULTS: An anterior dislocation occurred in 19 patients at an average of 40 days postoperatively. The average CA in patients who did and did not have a dislocation was 66 ± 8° and 45 ± 11°, respectively (P < .001). In 5 of 19 of the patients, a THA was performed for secondary osteoarthritis and 17 of 19 had a 28-mm femoral head. A CA ≥ 60° yielded a sensitivity of 93% and specificity of 90% for predicting an anterior dislocation in the present cohort. A CA ≥ 60° was associated with a significantly higher risk of anterior dislocation (odds ratio = 75.6; P < .001) compared to patients who had a CA<60 points. CONCLUSION: The optimal CA to avoid anterior dislocations in THA performed through the DAA should be less than 60°. LEVEL OF EVIDENCE: Cross-sectional study, Level III.

Femoro-Epiphyseal Acetabular Roof (FEAR) Index Values on Anteroposterior Pelvic Radiographs Significantly Increase With Hip Adduction and Decrease With Abduction.

PURPOSE: To investigate the impact of hip adduction and abduction on the femoro-epiphyseal acetabular roof (FEAR) index using conventional anteroposterior pelvic radiographs of patients with borderline hip dysplasia (BHD). METHODS: Patients with BHD (lateral center edge angle [LCEA] with values of 18° ≤ LCEA <25°) and who were subject to periacetabular osteotoym were selected from a consecutive retrospective cohort from January 2009 to January 2016. The hip ad-/abduction (adduction handled as negative values) and the FEAR index (lateral opening angles handled as positive values) were measured in the initially standardized acquired pelvic radiographs. Thereafter, using surgical planning software, different degrees of hip adduction and abduction were simulated from 20° of adduction to 30° of abduction, and the FEAR index was measured at each position. Pearson correlation was used to identify a potential correlation between the hip ad-/abduction and the FEAR index. RESULTS: Eighty-nine hips were included. Initial radiographs showed unintentional mean ad-/abduction of -5.3° ± 3.1° (range, -14° to 2°). The mean FEAR index at the initial ad-/abduction angle was -3.6° ± 7.2° (range, -18.0° to 16.0°) and was significantly different from neutral position (0° of ad-/abduction) -9.2° ± 7.0° (range, -27.0° to 10.0°) (P < .001). The FEAR index was negatively correlated to the hip ad-/abduction angle (r = 1, P < .001), with lower values for the FEAR index with the hip in abduction. CONCLUSIONS: Significant differences in FEAR index measurements were observed depending on hip ad-/abduction on pelvic radiographs. A linear change of the FEAR index of 5° per 5° of hip adduction or abduction could be demonstrated, with adduction resulting in increasing and abduction in decreasing values for the FEAR index. LEVEL OF EVIDENCE: Level III, diagnostic study.

Significant race and gender differences in anterior cruciate ligament tibial footprint location: a 3D-based analysis.

BACKGROUND: The aim of the present study was to identify potential race- or gender-specific differences in anterior cruciate ligament (ACL) tibial footprint location from the tibia anatomical coordinate system (tACS) origin, investigate the distances from the tibial footprint to the anterior root of the lateral meniscus (ARLM) and the medial tibial spine (MTS), determine how reliable the ARLM and MTS can be in locating the ACL tibial footprint, and assess the risk of iatrogenic ARLM injuries caused by using reamers with various diameters (7-10 mm). PATIENTS AND METHODS: Magnetic resonance images of 91 Chinese and 91 Caucasian subjects were used for the reconstruction of three-dimensional (3D) tibial and ACL tibial footprint models. The anatomical coordinate system was applied to reflect the anatomical locations of scanned samples. RESULTS: The average anteroposterior (A/P) tibial footprint location was 17.1 ± 2.3 mm and 20.0 ± 3.4 mm in Chinese and Caucasians, respectively (P < .001). The average mediolateral (M/L) tibial footprint location was 34.2 ± 2.4 mm and 37.4 ± 3.6 mm in Chinese and Caucasians, respectively (P < .001). The average difference between men and women was 2 mm in Chinese and 3.1 mm in Caucasians. The safe zone for tibial tunnel reaming to avoid ARLM injury was 2.2 mm and 1.9 mm away from the central tibial footprint in the Chinese and Caucasians, respectively. The probability of damaging the ARLM by using reamers with various diameters ranged from 0% for Chinese males with a 7 mm reamer to 30% in Caucasian females with a 10 mm reamer. CONCLUSIONS: The significant race- and gender-specific differences in the ACL tibial footprint should be taken in consideration during anatomic ACL reconstruction. The ARLM and MTS are reliable intraoperative landmarks for identifying the tibial ACL footprint. Caucasians and females might be more prone to iatrogenic ARLM injury. LEVEL OF EVIDENCE: III, cohort study. TRIAL REGISTRATION: This study has been approved by the ethical research committee of the General Hospital of Southern Theater Command of PLA under the code: [2019] No.10.

A novel method for evaluating combined component anteversion in total hip arthroplasty on cross-table lateral hip radiographs.

INTRODUCTION: Accurate measurement of combined component anteversion (CA) is important in evaluating the radiographic outcomes following total hip arthroplasty (THA). The aim of the present study was to evaluate the accuracy and reliability of a novel radiographic method in estimating CA in THA. MATERIALS AND METHODS: The radiographs and computer tomography of patients who underwent a primary THA were retrospectively reviewed, to measure the radiographic CA (CAr), defined as the angle between a line connecting the center of the femoral head to the most anterior rim of the acetabular cup and a line connecting the center of the femoral head to the base of the femoral head to allow a comparison with the CA measured on the CT (CACT). Subsequently, a computational simulation was performed to evaluate the effect of cup anteversion, inclination, stem anteversion, and leg rotation on the CAr and develop a formula that would correct the CAr according to the acetabular cup inclination based on the best-fit equation. RESULTS: In the retrospective analysis of 154 THA, the average CAr_cor, and CACT were 53 ± 11° and 54 ± 11° (p > 0.05), respectively. A strong correlation was found between CAr and CACT (r = 0.96, p < 0.001), with an average bias of - 0.5° between CAr_cor and CACT. In the computational simulation, the CAr was strongly affected by the cup anteversion, inclination, stem anteversion, and leg rotation. The formula to convert the CAr to CA_cor was: CA-cor = 1.3*Car - (17* In (Cup Inclination) - 31. CONCLUSION: The combined anteversion measurement of THA components on the lateral hip radiograph is accurate and reliable, implying that it could be routinely used postoperatively but also in patients with persistent complaints following a THA. LEVEL OF EVIDENCE: Cross-sectional study, Level III.

A Simple Preoperative Score Predicting Failure Following Decompression Surgery for Degenerative Lumbar Spinal Stenosis.

BACKGROUND CONTEXT: Proper patient selection is crucial for the outcome of surgically treated degenerative lumbar spinal stenosis (DLSS). Nevertheless, there is still not a clear consensus regarding the optimal treatment option for patients with DLSS. PURPOSE: To investigate the treatment failure rate and introduce a simple, preoperative score to aid surgical decision-making. STUDY DESIGN/SETTING: Retrospective observational study. PATIENT SAMPLE: Four hundred forty-five patients who underwent surgical decompression for DLSS. OUTCOME MEASURES: Treatment failure (defined as conversion to a fusion of a previously decompressed level) of lumbar decompression. MATERIALS AND METHODS: Several risk factors associated with worse outcomes and treatment failures, such as age, body mass index, smoking status, previous surgery, low back pain (LBP), facet joint effusion, disk degeneration, fatty infiltration of the paraspinal muscles, the presence of degenerative spondylolisthesis and the facet angulation, were investigated. RESULTS: At a mean follow-up of 44±31 months, 6.5% (29/445) of the patients underwent revision surgery with spinal fusion at an average of 3±9 months following the lumbar decompression due to low back or leg pain. The baseline LBP (≥7) [odds ratio (OR)=5.4, P <0.001], the presence of facet joint effusion (>2 mm) in magnetic resonance imaging (OR=4.2, P <0.001), and disk degeneration (Pfirrmann >4) (OR=3.2, P =0.03) were associated with an increased risk for treatment failure following decompression for DLSS. The receiver operating characteristic curve analysis demonstrated that a score≥6 points yielded a sensitivity of 90% and specificity of 64% for predicting a treatment failure following lumbar decompression for DLSS in the present cohort. CONCLUSIONS: The newly introduced score quantifying amounts of LBP, facet effusions, and disk degeneration, could predict treatment failure and the need for revision surgery for DLSS patients undergoing lumbar decompression without fusion. Patients with scores >6 have a high chance of needing fusion following decompression surgery. LEVEL OF EVIDENCE: Retrospective observational study, Level III.

Altered In Vivo Knee Kinematics and Lateral Compartment Contact Position During the Single-Leg Lunge After Medial Unicompartmental Knee Arthroplasty.

Background: Osteoarthritis (OA) progression in the lateral compartment is the most common reason for revision after medial unicompartmental knee arthroplasty (UKA). Altered contact kinematics in the lateral compartment may be related to the pathogenesis of OA. Purpose: To quantify the in vivo 6 degrees of freedom (6-DOF) knee kinematics and contact points in the lateral compartment during a single-leg lunge in knees after medial UKA and compare them with the contralateral native knee. Study Design: Descriptive laboratory study. Methods: Included were 13 patients (3 male, 10 female; mean age, 64.7 ± 6.2 years) who had undergone unilateral medial UKA. All patients underwent computed tomography preoperatively and 6 months postoperatively, and bilateral knee posture was tracked using dual fluoroscopic imaging system during a single-leg deep lunge to evaluate the in vivo 6-DOF kinematics. The closest points between the surface models of the femoral condyle and the tibial plateau were determined to locate the lateral compartment contact positions. The Wilcoxon signed-rank test was used to compare knee kinematics and lateral contact position between the UKA and native knees. Spearman correlation was used to test the associations of bilateral 6-DOF range difference and lateral compartment contact excursion difference with bilateral limb alignment difference and functional scores. Results: Compared with native knees, UKA knees had an increased anterior femoral translation of 2.0 ± 0.3 mm during the entire lunge (P < .05). The lateral contact position in UKA knees was located 2.0 ± 0.9 mm posteriorly and with 3.3 ± 4.0 mm less range of contact excursion than native knees (P < .05). Decreased range of lateral compartment contact excursion in the anterior-posterior direction was significantly associated with increased hip-knee-ankle angle in the UKA side (P < .05). Conclusion: The current study revealed altered knee 6-DOF kinematics and the reduced contact excursion range during single-leg lunge after unilateral medial UKA. Clinical Relevance: The altered contact kinematics and reduced range of contact excursion in UKA knees could lead to excessive cumulative articular surface contact stress, which is implicated in the pathogenesis of OA.

Medial stability and lateral flexibility of the collateral ligaments during mid-range flexion in medial-pivot total knee arthroplasty patients demonstrates favorable postoperative outcomes.

PURPOSE: The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA). METHODS: Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group. The attachment sites of the sMCL and LCL were marked to calculate the 3D wrapping length. The sMCL and LCL were divided into anterior, intermediate, and posterior portions (aMCL, iMCL, pMCL, aLCL, iLCL, pLCL). Correlations between lengths/elongation rate of ligament bundles from full extension to 100° flexion and the KSS were examined. RESULTS: The sMCL and LCL demonstrated relative stability in length at low flexion, but sMCL length decreased whereas LCL increased with further flexion on operated knees. The sMCL length increased at low flexion and remained stable with further flexion, while the LCL length decreased with flexion on the contralateral non-operated knees. The lengths of aMCL, iMCL, and pMCL showed moderate (0.5 < r < 0.7, p < 0.05) negative correlations with the KSS, and the lengths of aLCL, iLCL, and pLCL were positively correlated with the KSS at mid flexion on operated knees (p < 0.05). The elongation rates of aLCL, iLCL, and pLCL were negatively correlated with the KSS at high flexion on operated knees (p < 0.05). However, no significant correlations between the length of different bundles of sMCL or LCL with KSS were found on contralateral non-operated knees. CONCLUSIONS: The elongation pattern of sMCL/LCL on MP-TKA knees showed differences with contralateral non-operated knees. The sMCL is tense at low to middle flexion and relaxed at high flexion, while LCL is relaxed at low to middle flexion and tense at high flexion following MP-TKA. Medial stability and proper lateral flexibility during mid flexion were associated with favorable postoperative outcomes in MP-TKA patients. In contrast, lateral relaxation at deep flexion should be avoided when applying soft-tissue balancing in MP-TKA. LEVEL OF EVIDENCE: Level III.

Hybrid fixation of unicompartmental knee arthroplasty shows equivalent short-term implant survivorship and clinical scores compared to standard fixation techniques.

INTRODUCTION: There is a paucity of data regarding hybrid-fixated unicompartmental knee arthroplasty (UKA), and no study directly compared all three available fixation techniques (cementless, cemented, and hybrid). The hypothesis was that hybrid fixation might have a lower incidence of radiolucent lines (RLL) than cemented UKA, with equivalent outcomes to uncemented UKA. MATERIALS AND METHODS: A total of 104 UKA with a minimal follow-up of 1 year were retrospectively included, of which 40 were cemented, 41 cementless, and 23 hybrid prostheses. The functional outcomes scores included the Oxford Knee (OKS), Subjective Knee (SKS), and Forgotten Joint scores (FJS). RLLs, subsidence, and component positioning were assessed on radiographs. RESULTS: At a mean follow-up of 28 months, the survival rate was 95% for cemented UKA and 100% for the cementless and hybrid UKA (n.s.), respectively. Postoperative FJS (93 vs. 82 points, p = 0.007) and SKS (4.7 vs. 4.1 points, p = 0.001) were better in cementless than cemented UKA, with hybrid-fixated UKA in between the two (90 and 4.4 points, n.s.). Improvement of OKS preoperatively to postoperatively did not differ between the groups (n.s.). RLLs were more frequent in cemented (23%) compared to cementless (5%, p = 0.021) and hybrid UKA (9%, n.s.). With an incidence of 12%, subsidence occurred more commonly in cementless UKA compared to cemented (5%) and hybrid (0%) (n.s.) UKA. CONCLUSION: Hybrid fixation achieves equivalent results to standard UKA fixation techniques regarding implant survival and functional and radiological outcomes. Therefore, the hybrid fixation technique seems to be a valuable alternative as it combines the advantages of cemented tibial components with those of uncemented femoral components. LEVEL OF EVIDENCE: III.

Natural History of Degenerative Hip Abductor Tendon Lesions.

BACKGROUND: The best treatment of degenerative hip abductor tendon lesions remains largely unknown, as the natural course of the disease has not yet been reported. The aim of the present study was to investigate the natural history of symptomatic degenerative hip abductor lesions. HYPOTHESIS: Nonoperatively treated hip abductor lesions progress over time, resulting in refractory hip pain and low functional outcomes. STUDY DESIGN: Case series (prognosis); Level of evidence, 4. METHODS: Consecutive patients with greater trochanteric pain syndrome and degenerative changes on magnetic resonance imaging (MRI) of the symptomatic hip were included. Bilateral hip MRI scans and a clinical examination were performed at a minimum follow-up of 36 months to study the type and location of hip abductor lesion. Progression of a lesion was defined as a more severe lesion as compared with the initial MRI results or if the lesion extended to another, initially not involved, trochanteric facet. The muscle's fatty infiltration (FI) was also described. RESULTS: From 106 patients identified, 58 patients (64 hips) aged 66 ± 14 years (mean ± SD) agreed to return to the clinic for follow-up MRI and met the inclusion criteria. At a mean 71-month follow-up, an overall 34% (22/64) of lesions had progressed over time: from trochanteric bursitis to tendinopathy (9/64, 14%) or partial tear (5/64, 8%), from tendinopathy to partial tear (4/64, 6%), from a partial to complete tear (3/64, 4.5%), and with 1 complete tear (1/64, 1.5%) extending to another trochanteric facet. Interestingly, 90% of partial tears remained stable or transformed into a scar. Although patients with a progressive lesion experienced more trochanteric pain (visual analog scale, 4.6 vs 2.8; P = .001), the functional outcomes were comparable with patients with a stable lesion. The majority of hips with a partial tear (64%) demonstrated a progression of gluteus minimus FI from a median grade of 1 to 2, whereas only 1 hip (3%) progressed from grade 2 to 3. Only 3 hips (9%) with a partial tear had a progression of gluteus medius FI, which did not differ significantly from the contralateral unaffected side. CONCLUSION: Nonoperative treatment might be a valid long-term option for degenerative hip abductor lesions, especially for partial tears, which demonstrated a low risk of clinically relevant progression or muscle FI and similar clinical outcomes to those reported in the literature for operatively treated hip abductor tendon lesions.

Surgical Outcomes and Analysis of Quality of Life Following Knee Arthroplasty in Very Elderly Patients.

In an aging population, the incidence of severe knee osteoarthritis in very elderly patients increases, leading to functional impairment and loss of independence. Knee replacement could be an effective treatment but is often denied due to fear of increased complication rate with advanced age. The objective of this study was to investigate complication rate, mortality, clinical outcome, and quality-adjusted life years (QALYs) of primary knee replacement in very elderly patients, defined as 83 years or older. Medical records of 85 cases, receiving a primary total (total knee arthroplasty [TKA]) or unicompartmental (unicompartmental knee arthroplasty [UKA]) knee replacement, aged 83 years or older at the time of surgery, were retrospectively reviewed for surgical and medical complications as well as survivorship. Functional outcome was obtained by Oxford Knee Score (OKS) and QALY. At a mean follow-up of 21 months (TKA) and 24 months (UKA), surgical and medical complication rates were 9.7 and 8.1% for TKA and 4.3 and 4.3% for UKA, respectively. One-year survival rate was 98.4% in TKA and 98.8% in UKA, the 5-year survival rate was 83.1 and 86.6%, respectively. OKS improved from 19 to 41 points in TKA and 23 to 40 points in UKA. Mean QALYs were 4.1 years for TKA and 3.9 years for UKA. TKA and UKA are safe and reliable surgical procedures in treating end-stage osteoarthritis in very elderly patients. Patients might benefit from improved pain, function, and quality of life. The mortality rate and overall complication rate were low, although slightly higher than reported in cohorts with younger patients. If the patient is suitable, UKA might be preferred over TKA, as the complication rate was significantly lower. Patients should not be excluded from knee replacement based on their age alone, but careful patient selection, peri- and postoperative optimization, and awareness for complications are quintessential for successful treatment.

The effect of lumbar spinal fusion on native acetabular anteinclination in standing position.

PURPOSE: The complex and dynamic spinopelvic interplay is not well understood. The aims of the present study were to investigate the following: (1) whether native acetabular anteinclination (AI) in standing position changes following lumbar spinal fusion (LSF); (2) potential correlations between AI change (ΔAI) and several spinopelvic parameters such as the change in lumbar lordosis (ΔLL), pelvic tilt (ΔPT), and anterior pelvic plane angle (ΔaPP). METHODS: A total of 485 patients (Males: 262, Females: 223) with an average age of 64 ± 13 years who underwent a primary LSF were identified from our institutional database. The difference (Δ) between pre-and postoperative acetabular anteinclination (AI), lumbar lordosis (LL), anterior pelvic plane angle (aPP), sacral slope (SS), and pelvic tilt (PT) were measured on a standing lateral radiograph (EOS®) and compared to find the effect of LSF on the lumbopelvic geometry. RESULTS: Following LSF, the average absolute ΔAI was 5.4 ± 4 (0 to 26)°, ΔLL: 5.5 ± 4 (0 to 27)°, ΔaPP: 5.4 ± 4 (0 to 38)°, ΔPT: 7 ± 5 (0 to 33)° and ΔSS: 5.3 ± 4 (0 to 33)°. No significant differences were observed between LSF levels. A ΔAI ≥ 10° was observed in 66 (13.6%) and ΔAI ≥ 20° in 5 (1%) patients. The Pearson correlation demonstrated a strong negative correlation of ΔAI with ΔLL (r = 0.72, p < .001). CONCLUSION: Clinical decision-making should consider the relationship between native anteinclination and lumbar lordosis to reduce the risk of functional acetabular component malalignment in patients with concomitant hip and spine pathology. LEVEL OF EVIDENCE: Retrospective case-control study, Level III.

Quantitative cotyloid fossa thickness and proximity to obturator neurovascular bundle: implications for arthroscopic ligamentum teres reconstruction.

The aim of the present study was to report the in vivo thickness of the cotyloid fossa at the acetabular ligamentum teres (LT) attachment and investigate the clearance of the obturator neurovascular bundle. Fifty-five consecutive patients undergoing a total hip arthroplasty for hip osteoarthritis were included. The thickness of the cotyloid fossa was measured at the acetabular LT attachment using a standard depth gauge. The minimal distance (clearance) of the obturator neurovascular bundle to the center of the acetabular LT attachment was measured in 7 patients (14 hips) who also underwent a computed tomography angiography. The average thickness of the cotyloid fossa at the acetabular LT attachment was 4.1 ± 2.3 (range: 1-10) mm. The obturator vein was closest to the acetabular LT attachment, but the clearance was more than the defined safe zone of 15 mm in all cases. Based on the current findings, it can be assumed that bone anchors might not be suitable for fixation of the graft in LT reconstruction (LTR) and an alternative implant such as a cortical button should be considered. Acetabular fixation of the graft with a 12-mm cortical button is relatively safe concerning injury to obturator neurovascular structures. The results of the present study provide a better understanding of the cotyloid fossa anatomy and might be relevant for surgeons who perform arthroscopic LTR.

Reverse Total Shoulder Arthroplasty in Patients Who Exceeded Their Life-Expectancy: A Retrospective Study.

Background: Reverse total shoulder arthroplasty (RTSA) has become an established treatment for cuff arthropathy, severe osteoarthritis and in certain fracture cases. Due to the increasingly aging population, patients who have already exceeded their life-expectancy pose a significant challenge to the shoulder surgeon. Methods: Patients older than 83 years who received a RTSA were included. Elective cases were compared to fracture cases. Patient demographics, hospital stay length, complication rate, functional outcome, patient reported outcome scores and mortality were assessed retrospectively. Results: We included 110 cases, 48 in the elective group and 62 in the fracture group. The average age at time of surgery was 86.6 ± 3.5 years. Mean follow-up was 30 months. Elective cases had a significant shorter hospital stay length (P = .014). Functional outcome scores showed better results for the elective group with ASES 79 ± 12 vs 69 ± 19 (P = .07), QuickDASH 29 ± 16 vs 37 ± 21 (P = .22), subjective shoulder value 86 ± 14 vs 75 ± 19 (P = .04*) and VAS .7 ± 1.5 vs 2.1 ± 2.5 (P = .02*). There was no significant difference in ROM and mean quality-adjusted-life-years (QALY) with 3.2 ± 1.8 vs 3.5 ± 2.5 years (P = .69). The complication rate requiring surgical intervention was 2.4% in the elective and 6.5% in the fracture group. The 1-year mortality was 3 (6%) respectively 9 (15%). Conclusion: RTSA in elderly patients can be successful with good functional outcomes. Age should not be a contraindication. Instead, the patient's activity level and quality of life should be taken into account. Elective RTSA show better functional outcome scores and lower complication rates compared to RTSA in proximal humeral fractures.