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Background: Pudendal nerve entrapment (PNE) is an underdiagnosed condition affecting a spectrum of pelvic functions, primarily pain, as outlined by Nantes diagnostic criteria. Although numerous surgical decompression techniques are available for its management, consensus on efficacy and safety is lacking. This study conducts a systematic review and meta-analysis to assess the efficacy and complication rates of the main surgical decompression techniques., Methods: A comprehensive literature search was conducted in PubMed®, Embase®, Web of Science®, and ClinicalTrails.gov® on 19th of April 2023. Initial screening involved title and abstract evaluation, with subsequent retrieval and assessment of abstracts and full-text articles. Studies assessing pain outcomes before and after surgical release of the pudendal nerve were included. Studies without full-text, focusing on diagnostic methods or with outcomes relating solely to LUTS, digestive symptoms, or sexual dysfunction, were excluded. Risk of bias assessement was conducted using the National Institute of Health (NIH) Study Quality Assessment tool. Studies were categorized based on three surgical techniques: perineal, transgluteal, and laparoscopic transperitoneal. Random-effects meta-analysis with subgroup analysis were used. Meta-regression analyses were conducted to investigate the influence of covariates on the observed outcomes., Results: Nineteen studies, comprising 810 patients, were included. The overall significant pain relief rate across all techniques was estimated at 0.67 (95% CI 0.54 to 0.78) with considerable heterogeneity (I 2  = 80.4%). Subgroup analysis revealed success rate for different techniques: laparoscopic (0.91, 95% CI 0.64 to 0.98), perineal (0.69, 95% CI 0.52 to 0.82), and transgluteal (0.50, 95% CI 0.37 to 0.63). The laparoscopic technique exhibited a complication rate of 16.0%. Meta-regression indicated that patient age and median follow-up significantly influenced outcomes., Conclusion: While comparing surgical techniques is challenging, this meta-analysis highlights important outcome differences. The laparoscopic technique appears most promising for pain improvement. However, the study also emphasizes the need for further robust, long-term research due to significant heterogeneity across studies and prevelent risk of bias. PROSPERO database: CRD42023496564., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Introduction: Despite the existence of diverse total knee implant designs, few data is available on the relationship between the level of implant constraint and the postoperative joint stability in the frontal plane and strain in the collateral ligaments. The current study aimed to document this relation in an ex vivo setting., Materials and Methods: Six fresh-frozen lower limbs underwent imaging for preparation of specimen-specific surgical guides. Specimens were dissected and assessed for joint laxity using the varus-valgus stress tests at fixed knee flexion angles. A handheld dynamometer applied tensile loads at the ankle, thereby resulting in a knee abduction-adduction moment of 10 Nm. Tibiofemoral kinematics were calculated using an optical motion capture system, while extensometers attached to medial collateral (MCL) and lateral collateral ligament (LCL) measured strain. Native joint testing was followed by four TKA designs from a single implant line-cruciate retaining, posterior stabilised, varus-valgus constrained and hinged knee (HK)-and subsequent testing after each implantation. Repeated measures linear mixed-models (p < 0.05) were used to compare preoperative vs. postoperative data on frontal plane laxity and collateral ligament strain., Results: Increasing implant constraint reduced frontal plane laxity across knee flexion, especially in deep flexion (r 2  > 0.76), and MCL strain in extension; however, LCL strain reduction was not consistent. Frontal plane laxity increased with knee flexion angle, but similar trends were inconclusive for ligament strain. HK reduced joint laxity and ligament strain as compared to the native condition consistently across knee flexion angle, with significant reductions in flexion (p < 0.024) and extension (p < 0.001), respectively, thereby elucidating the implant design-induced joint stability. Ligament strain exhibited a strong positive correlation with varus-valgus alignment (r 2  = 0.96), notwithstanding knee flexion angle or TKA implant design., Conclusion: The study demonstrated that increasing the constraint of a TKA resulted in lower frontal plane laxity of the knee. With implant features impacting laxity in the coronal plane, consequentially affecting strain in collateral ligaments, surgeons must consider these factors when deciding a TKA implant, especially for primary TKA., Level of Evidence: V., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Femoral component malrotation in total knee arthroplasty (TKA) is clinically proven to cause dissatisfaction and impaired function. This study is an attempt to characterize the tibiofemoral kinematics following femoral malrotation in posterior stabilized (PS) TKA. It was hypothesized that internal malrotation would introduce the most pronounced changes., Methods: Six fresh-frozen cadaver specimens were mounted in a kinematic rig. Three motion patterns were applied with the native knee and following PS TKA (passive motion, open chain extension, and squatting) while infrared cameras recorded the trajectories of markers attached to femur and tibia. Three different femoral implants were tested: a conventional posterior stabilized component, and adapted components of the same implant with 5° of intrinsic external and internal rotation, respectively., Results: The implantation of the PS TKA resulted in less tibial internal rotation (squat 33-70°, p < 0.05) and the medial femoral condyle shifted posteriorly especially in deep flexion (squat 84-111°, p < 0.05). Internal component malrotation caused internal rotation and abduction of the tibia in flexion (squat 33-111°, p < 0.05), an elevated (squat 43-111°, p < 0.05) and more anterior (passive 61-126°, p < 0.05) located medial femoral condyle and a lateral femoral condyle located more posterior and inferior (squat 73-111°, p < 0.05) than in the neutrally aligned TKA. External component malrotation caused only little changes under passive motion. Under a squat there was less internal rotation and more adduction to the tibia (33-111°, p < 0.05). The medial femoral condyle was moved more posterior (squat 59-97°, p < 0.05), the lateral femoral condyle more superior (squat 54-105°, p < 0.05) than in the neutrally aligned TKA., Conclusion: The greatest differences to the native tibiofemoral kinematics were introduced by internal rotation of the femoral component. Also neutrally and externally rotated femoral components introduce kinematic changes, but to a lesser extent. With respect to the alterations introduced to kinematics internal malrotation should be avoided when performing PS TKA.

Background: Oxidized zirconium (OxZr) is produced by thermally driven oxidization creating an oxidized surface with the properties of a ceramic at the top of the Zr metal substrate. OxZr is much harder and has a lower coefficient of friction than cobalt-chrome (CoCr), both leading to better wear characteristics. We evaluated and compared damage to the cartilage of porcine patella plugs, articulating against OxZr vs CoCr. Our hypothesis was that, owing to its better wear properties, OxZr would damage cartilage less than CoCr. If this is true, OxZr might be a better material for the femoral component during total knee arthroplasty if the patella is not resurfaced., Methods: Twenty-one plugs from porcine patellae were prepared and tested in a reciprocating pin-on-disk machine while lubricated with bovine serum and under a constant load. Three different configurations were tested: cartilage-cartilage as the control group, cartilage-OxZr, and cartilage-CoCr. Macroscopic appearance, cartilage thickness, and the modified Mankin score were evaluated after 400,000 wear cycles., Results: The control group showed statistically significant less damage than plugs articulating against both other materials. Cartilage plugs articulating against OxZr were statistically significantly less damaged than those articulating against CoCr., Conclusion: Although replacing cartilage by an implant always leads to deterioration of the cartilage counterface, OxZr results in less damage than CoCr. The use of OxZr might thus be preferable to CoCr in case of total knee arthroplasty without patella resurfacing., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: Balancing unicondylar knee arthroplasty (UKA) is challenging. If not performed properly, it may lead to implant loosening or progression of osteoarthritis in the preserved compartment. This study was aimed to document the biomechanical effects of improper balancing. We hypothesised that overstuffing would lead to more valgus, higher strain in the medial collateral ligament (sMCL), and higher lateral contact force., Methods: Six fresh-frozen cadaver specimens were mounted in a kinematic rig. Three motion patterns were applied with the native knee and following medial UKA (passive motion, open-chain extension, and squatting), while infrared cameras recorded the trajectories of markers attached to femur and tibia. Three inlay thicknesses were tested (8, 9, 10 mm)., Results: Overstuffed knees were in more valgus and showed less tibial rotation and higher strains in the sMCL (p < 0.05). Lateral contact forces were higher in some specimens and lower in others. Stiffening of the medial compartment by UKA, even well balanced, already leads to a knee more in valgus with a more stressed sMCL. Overstuffing increases these effects. Knees with a tight sMCL may even see lower lateral contact force. Biomechanics were closest to the native knee with understuffing., Conclusion: The first two hypotheses were confirmed, but not the latter. This underlines the importance of optimal balancing. Overstuffing should certainly be avoided. Although kinematics is only slightly affected, contact forces and ligament strains are considerably changed and this might be of more clinical importance. It is advisable to use thinner inlays, if stability is not compromised.

Purpose: Most total knee arthroplasty tibial components are metal-backed, but an alternative tibial component made entirely of polyethylene (all-polyethylene design) exists. While several clinical studies have shown that all-poly design performs similarly to the metal-backed, the objective of this study is to perform a biomechanical comparison., Methods: Loads, constraints and geometries during a squat activity at 120° of flexion were obtained from a validated musculoskeletal model and applied to a finite element model. Stresses in the tibia and micromotions at the bone-implant interface were evaluated for several implant configurations: (1) three different thicknesses of the cement penetration under the baseplate (2, 3 and 4 mm), (2) the presence or absence of a cement layer around the stem of the tibial tray and (3) three different bone conditions (physiological, osteopenic and osteoporotic bone)., Results: All-polyethylene tibial components resulted in significantly higher (p < 0.001) and more uneven stress distributions in the cancellous bone under the baseplate (peak difference: +128.4 %) and fivefold increased micromotions (p < 0.001). Performance of both implant designs worsened with poorer bone quality with peaks in stress and micromotion variations of +40.8 and +54.0 %, respectively (p < 0.001). Performance improvements when the stem was cemented were not statistically significant (n.s.)., Conclusion: The metal-backed design showed better biomechanical performance during a squat activity at 120° of flexion compared to the all-polyethylene design. These results should be considered when selecting the appropriate tibial component for a patient, especially in the presence of osteoporotic bone or if intense physical activity is foreseen.

Purpose: Currently, controversy exists whether restoration of neutral mechanical alignment should be attempted in all patients undergoing TKA. Our hypothesis was that restoration of constitutional rather than neutral mechanical alignment may in theory lead to a more physiological strain pattern in the collateral ligaments; therefore, it could potentially be beneficial to patients. Thus, the aim of this study was to measure collateral ligament strains during three motor tasks in the native knee and compare them with the strains noted after TKA in different post-operative alignment conditions., Methods: Six cadaver specimens (approval number ML4190 from the Research Ethics Committee of University of Leuven, Belgium) were examined using a validated knee kinematics rig under physiological loading conditions. The effect of coronal malalignment was evaluated by using custom-made tibial implant inserts that induced different alignment conditions. The study of six specimens allows us to show that a difference in the mean strains in MCL and LCL of 3.6 and 5.8 %, respectively, was statistically significant with a probability (power) of 0.8., Results: The results indicated that after TKA insertion, the strains in the collateral ligaments closely resembled the pre-operative pattern of the native knee specimens when constitutional alignment was restored. Restoration to neutral mechanical alignment was associated with greater collateral strain deviations from the native knee., Conclusion: Based upon this study, it was concluded that restoration of constitutional alignment within a "safe zone" of ±2° during TKA leads to more physiological peri-articular soft tissue strains during loaded as well as unloaded motor tasks.