Consensus statement on unicompartmental knee replacement: A collaboration between BASK and EKS.

BACKGROUND: The aim of this study was to deliver consensus recommendations for the clinical practice of unicompartmental knee arthroplasty (UKA). METHODS: Members of the British Association for Surgery of the Knee (BASK) and European Knee Society (EKS) were invited to attend a joint meeting in London, UK (December 2019). A formal consensus process was undertaken at the meeting incorporating a multiple round Delphi exercise, with group discussion of areas of agreement and disagreement between rounds. Eighty delegates attended the meeting and five consensus statements were considered and revised, with a threshold level of 80% agreement required as the definition consensus. RESULTS: Five consensus statements with accompanying supporting evidence and text were agreed following two rounds of the process: (1) UKA should be offered as a successful alternative to TKA in patients undergoing arthroplasty who meet agreed indications; (2) When consenting a patient for UKA, information including the benefits and risks that are specific to UKA, should be tailored to and discussed with the individual patient; (3) Evidence suggests that surgeons should avoid low-volume use of UKA to optimise outcomes for their patients; (4) Surgeons should use the contemporary evidence-based indications and contraindications for medial UKA; (5) Knee arthroplasty surgeons should have exposure to and training in UKA. CONCLUSIONS: The agreed joint BASK-EKS consensus statements on UKA practice are recommended as the contemporary basis of optimal care for these patients and should inform future training and service developments.

Titanium niobium nitride knee implants are not inferior to chrome cobalt components for primary total knee arthroplasty at medium-term follow-up.

BACKGROUND: Oxidized zirconium (Oxinium), titanium nitride (TiN) or titanium niobium nitride (TiNbN) coated implants became in recent years available for an increasing amount of total knee arthroplasty (TKA) systems. The hypothesis of this study was that the use of TiNbN-coated components would not lead to inferior results compared to conventional implants and that none of the metal hypersensitivity patients receiving TiNbN-coated implants would require revision for metal allergy. MATERIALS AND METHODS: This retrospective study compared 53 Titanium Niobium Nitride coated TKA with 103 conventional chrome cobalt implants of the same design. Patients were evaluated at a minimal follow-up of 3 years. RESULTS: No differences in clinical, radiological or patient-reported outcome measurements were observed between these groups. A survivorship of 96% without differences in revision rates was observed at medium-term follow-up of 6.5 years. DISCUSSION: Metal allergy leading to contact or generalized dermatitis after TKA is very rare and usually linked to chrome or cobalt hypersensitivity. Nickel release from knee implants has not been shown to lead to cutaneous symptoms, but unexplained pain and swelling, peri-prosthetic osteolysis and component loosening remain potential issues not fully understood. The use of coated implants eliminates this factor from the diagnostic equation in case of postoperative dissatisfaction. CONCLUSION: The use of titanium niobium nitride coated implants for primary knee osteoarthritis in self-reported metal hypersensitivity patients shows similar outcomes and survivorship rates as conventional chrome cobalt TKA, with no revisions for allergy at medium-term follow-up.

Cutting-Edge Approaches in Arthroplasty: Before, during and after Surgery.

Personalised medicine was introduced in arthroplasty a long time ago with the aim of respecting each individual person for their unique personal characteristics in order to further improve outcomes [...].

Higher sensitivity with the lever sign test for diagnosis of anterior cruciate ligament rupture in the emergency department.

INTRODUCTION: The objective of this study was to assess the diagnostic value of the "lever sign test" to diagnose ACL rupture and to compare this test to the two most commonly used, the Lachman and anterior drawer test. METHOD: This prospective study was performed in the ED of the Cliniques Universitaires Saint-Luc (Brussels, Belgium) from March 2017 to May 2019. 52 patients were included undergoing knee trauma, within 8 days, with an initial radiograph excluding a fracture (except Segond fracture or tibial spine fracture). On clinical investigation, patients showed a positive lever sign test and/or a positive Lachman test and/or a positive anterior drawer test. Exclusion criteria were a complete rupture of the knee extensor mechanism and patellar dislocation. All the physicians involved in this study were residents in training. An MRI was performed within 3 weeks for all included patients after the clinical examination. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were investigated for all three tests with MRI used as our reference standard. RESULTS: Forty out of 52 patients suffered an ACL rupture (77%) and 12 did not (23%). The sensitivity, specificity, PPV and NPV of the lever sign test were respectively 92.5%, 25% 82% and 50%. Those of the Lachman test were 54%, 54.5%, 81% and 25%, and those of the anterior drawer test were 56%, 82%, 90.5% and 37.5%. Twelve out of 40 ACL ruptures (30%) were diagnosed exclusively with a positive lever sign test. CONCLUSION: When investigating acute ACL ruptures (< 8 days) in the ED, the lever sign test offers a sensitivity of 92.5%, far superior to that of other well-known clinical tests. The lever sign test is relatively pain-free, easy to perform and its visual interpretation requires less experience. Positive lever sign test at the ED should lead to an MRI to combine high clinical sensitivity with high MRI specificity.

Lower total blood loss in total knee arthroplasty with a low-pressure tourniquet than without.

Tourniquet-use has been described in litera- ture as a surgical factor leading to increased post-operative hidden blood loss in total knee arthroplasty (TKA). The hypothesis for this retro- spective study was that low-pressure tourniquet TKA would offer the benefits of tourniquet surgery without the potential negative effects on late blood loss after the procedure. Therefore, this study evaluated total (TBL) and hidden blood loss (HBL) in TKA with or without a tourniquet. We retrospectively compared two groups : one group (n= 54) undergoing TKA without a tourniquet and one group with a low-pressure tourniquet (n= 110). The outcomes compared were hemoglobin levels 2 weeks before surgery and at days 2 and 4 after surgery to calculate total and hidden blood loss, transfusion rate, and functional outcome. A higher total blood loss was observed in the no tourniquet group with a mean loss of 1073 mL against 890 mL in the tourniquet group (p-value = 0,003). Hidden blood loss values between both groups were statistically not significant : in the no-tourniquet group, Hb drop between D2 and D4 was 0.5 g/dL against 0.4 g/ dL in the low-pressure tourniquet group. The tourniquet-less group did not present with better functional scores. This study showed that low- pressure tourniquet use reduces TBL without increasing HBL in TKA.

Varus Knee Deformity Classification Based on Degree and Extra- or Intra-Articular Location of Coronal Deformity and Osteoarthritis Grade.

BACKGROUND: Medial coronal plane malalignment, also known as varus alignment, is commonly reported in osteoarthritic knees. Although the degree of deformity provides some insight regarding the severity of the disease, it does not always reflect the potential complexity of the surgical treatment. METHODS: This prospective observational study was conducted by analyzing the radiographs of 100 consecutive knees in patients undergoing total knee arthroplasty. For each knee, coronal alignment, expressed as the hip-knee-ankle angle, was measured on a full-leg standing radiograph and classified in 3 stages. The primary location of the varus deformity was identified as intra-articular and/or extra-articular. Additionally, knees were evaluated to assess for 10 radiographic features of varus deformity and then classified in 3 grades of osteoarthritis severity. RESULTS: The mean (and standard deviation) preoperative varus deformity was 11° ± 6° of varus (hip-knee-ankle, 169°), as measured on standardized full-leg radiographs. Extra-articular varus deformity was observed in 14% of patients. A higher number of radiographic features of varus severity corresponded with higher degrees of deformity. Varus grade correlated strongly with stage of varus deformity. Twenty-three (100%) of 23 stage-III deformities had grade-C features; however, 13 (48%) of 27 stage-I patients also had grade-C disease. CONCLUSIONS: One of every 7 osteoarthritis patients with varus deformity had an extra-articular deformity, and 1 of 2 of these patients had severe intra-articular disease (grade C) despite limited coronal deformity (stage I). These findings reconfirm the need for individual deformity analysis that accounts for the degree, location, and severity of the varus deformity. This insight may help to formulate an algorithmic treatment approach specific to the epiphyseal knee anatomy of the patient and according to the surgical preferences of the surgeon. CLINICAL RELEVANCE: Knee surgeons tend to consider knees with higher degrees of coronal deformity as more technically difficult, but the present study shows that knees with less deformity can still present with severe grades of osteoarthritis inside the knee, leading to more challenging joint reconstruction.

Contemporary knee arthroplasty: one fits all or time for diversity?

INTRODUCTION: Total knee arthroplasty (TKA) has historically been the preferred solution for any type of knee osteoarthritis, independently of the number of compartments involved. In these days of patient-specific medicine, mono-compartmental disease could also be approached with a more individualized treatment, such as partial knee arthroplasty (PKA). Off-the-shelf (OTS) implants are often the compromise of averages and means of a limited series of anatomical parameters retrieved from patients and the pressure of cost control by limited inventory. Personalized medicine requires respect and interest for the individual shape and alignment of each patient. MATERIALS AND METHODS: A Pubmed and Google Scholar search were performed with the following terms: "patient-specific knee" and "arthroplasty" and "custom implant" and "total knee replacement" and "partial knee replacement" and "patellofemoral knee replacement" and "bicompartmental knee replacement". The full text of 90 articles was used to write this narrative review. RESULTS: Unicondylar, patellofemoral and bicompartmental knee arthroplasty are successful treatment options, which can be considered over TKA for their bone and ligament sparing character and the superior functional outcome that can be obtained with resurfacing procedures. For TKA, where compromises dominate our choices, especially in patients with individual variations of their personal anatomy outside of the standard, a customized implant could be a preferable solution. CONCLUSION: TKA might not be the only solution for every patient with knee osteoarthritis, if personalized medicine wants to be offered. Patient-specific mono-compartmental resurfacing solutions, such as partial knee arthroplasty, can be part of the treatment options proposed by the expert surgeon. Customized implants and personalized alignment options have the potential to further improve clinical outcome by identifying the individual morphotype and respecting the diversity of the surgical population.

Vitamin E-enriched polyethylene bearings are not inferior to Arcom bearings in primary total knee arthroplasty at medium-term follow-up.

INTRODUCTION: The release of wear particles can be responsible for periprosthetic osteolysis, which can in turn, lead to aseptic loosening. Vitamin E-infused polyethylene (HXLPE Vit-E) has been shown, in vitro, to be more resistant to wear than conventional polyethylene (UHMWPE) by its crosslinking (HXLPE) and its higher resistance to oxidation. After reading a case report of a fracture of a vitamin E-enriched HXLPE bearing, the aim of this retrospective study was to evaluate fracture risk and clinical inferiority or not of vitamin-E HXLPE compared to conventional polyethylene in total knee arthroplasty (TKA). MATERIALS AND METHODS: Three hundred and forty-nine patients (403 TKAs) were contacted, to find out whether they had undergone revision surgery for any reason after a mean (SD) of 7 (1.5) years. Follow-up control radiographs were analyzed for periprosthetic radiolucent lines (RLL) and loosening. Two different Patient Reported Outcome Measurements Scores (PROMS), KOOS and FJS-12, were utilized to assess the daily functionality and identify potential problems. RESULTS: No statistically significant difference in revision rate, occurrence of aseptic loosening or RLL nor outcome as measured with PROMS was observed. CONCLUSIONS: No bearing fractures or clinical inferiority was observed for vitamin E-enriched HXLPE at medium-term follow-up (7 years) compared to conventional Arcom polyethylene. LEVEL OF EVIDENCE: Level III, therapeutic study.

Local infiltration analgesia with additional intraarticular catheter provide better pain relief compared to single-shot local infiltration analgesia in TKA.

PURPOSE: Local infiltration analgesia (LIA) has been proven to be efficient in total knee arthroplasty (TKA). However, the effect of single-shot LIA is temporarily limited. The objective of this prospective trial was to investigate if the potential benefits resulting from LIA can be prolonged by a continuous intra-articular perfusion of LIA. The hypothesis of the present study was that the use of an additional continuous intra-articular perfusion delivering LIA would result in less pain and better function compared to single-shot LIA in the immediate post-operative period. METHODS: 50 consecutively selected patients undergoing TKA received either a single-shot LIA (S-LIA group, 25 knees) or single-shot LIA combined with a continuous post-operative intra-articular perfusion for three post-operative days (CP-LIA group, 25 knees). VAS (visual analogue scale) for pain, pain medication consumption and flexion ability were recorded postoperatively for 6 days. All patients had the same implant, surgeon and intra- as well as post-operative setting. RESULTS: The VAS score was significantly better for CP-LIA 6 h after surgery and on post-operative day 1, 2 and 6. There was no significant difference with regard to additional opioid consumption or flexion ability of the knee. However, there was a trend of the CP-LIA group requiring less additional opioids over the complete post-operative period compared to the S-LIA group. There were no complications or revisions. CONCLUSION: LIA combined with an additional intra-articular catheter provides better short-term pain control compared to single-shot LIA. However, no significant differences in terms of knee flexion were observed. This limited benefit should be balanced against the additional costs and the possible higher risk of infection. LEVEL OF EVIDENCE: Level II.

Additional periarticular catheter shows no superiority over single-shot local infiltration analgesia alone in unicondylar knee replacement.

PURPOSE: Local infiltration analgesia (LIA) has attracted growing interest in recent years. To prolong the positive effects of LIA, a continuous intraarticular perfusion has been introduced in total knee arthroplasty with good clinical results. The purpose of the present study was to evaluate if similar results can be obtained with the use of a continuous periarticular perfusion in unicondylar knee arthroplasty (UKA). METHODS: 50 consecutively selected patients undergoing UKA received either a single-shot LIA (control group; n = 25) or single-shot LIA combined with a continuous postoperative periarticular perfusion for 2 postoperative days (intervention group, n = 25). VAS (visual analogue scale) for pain, pain medication consumption and range of flexion were recorded postoperatively for 6 days. The catheter was removed after 2 days. RESULTS: Only minor advantages of using a continuous periarticular catheter could be shown. Patients in the intervention group showed significant lower VAS scores on day 1 and required significant less pain medication on day 6. Further, there was a significant difference in the range of flexion on day 3, on which patients of the intervention group were able to bend the knee joint on average by 12° more than patients of the control group. On the other days, any significant differences between the two groups were not observed. CONCLUSION: In summary, the present study could not identify any superiority of a periarticular catheter over single-shot LIA in UKA. Because of additional costs and the potential risk of infection, the conclusion of this study is to not recommend adding a periarticular catheter to the single-shot LIA in UKA. LEVEL OF EVIDENCE: II.

Variations in medial and lateral slope and medial proximal tibial angle.

PURPOSE: The primary objective of this study was to quantify the variations of the medial posterior tibial slope (MPTS) and the lateral posterior tibial slope (LPTS), as well as of the medial proximal tibial angle (MPTA), and to determine the fraction of patients for which standard techniques including different alignment techniques would result in alteration of the patient's individual posterior tibial slope (PTS) and MPTA. Furthermore, it was of interest if a positive correlation between PTS and MPTA or between medial and lateral slope exists. METHODS: A retrospective study was performed on CT-scans of 234 consecutively selected European patients undergoing individual total knee replacement. All measurements were done on three-dimensional CAD models, which were generated on the basis of individual CT-scans, including the hip, knee, and ankle center. Measurements included the medial and lateral PTS and the MPTA. PTS was measured as the angle between the patient's articular surface and a plane perpendicular to the mechanical axis of the tibia in the sagittal plane. MPTA was defined as the angle between the tibial mechanical axis and the proximal articular surface of the tibia in the coronal plane. RESULTS: Analysis revealed a wide variation of the MPTS, LPTS, and MPTA among the patients. MPTS and LPTS varied significantly both interindividually and intraindividually. The range of PTS was up to 20° for MPTS (from - 4.3° to 16.8°) and for LPTS (from - 2.9 to 17.2°). The mean intraindividual difference between MPTS and LPTS in the same knee was 2.6° (SD 2.0) with a maximum of 9.5°. MPTA ranged from 79.8 to 92.1° with a mean of 86.6° (SD ± 2.4). Statistical analysis revealed a weak positive correlation between MPTA and MPTS. CONCLUSION: The study demonstrates a huge interindividual variability in PTS and MPTA as well as significant intraindividual differences in MPTS and LPTS. Therefore, the question arises, whether the use of standard techniques, including fixed PTSs and MPTAs, is sufficient to address every single patient's individual anatomy. LEVEL OF EVIDENCE: III.

Radiolucent lines around knee arthroplasty components : a narrative review.

Aseptic loosening of total knee arthroplasty (TKA) components is one of the frequent reasons for early revision together with infection and instability. Aseptic loosening is usually preceded by the observation of radiolucent lines (RLL) on radiographs. Radiolucent lines have conventionally been considered a sign of osteolysis due to particles disease of either polyethylene or cement wear. However, RLL can be observed quite early after TKA, way before wear and osteolysis can even occur. Immediate postoperative RLL are secondary to surgical technique with either inadequate cement penetration in sclerotic bone, insufficient preparation of the bone or malpositioning of the component relative to the bone cuts. This type of RLL can be observed radiologically but remains often without clinical symptoms. Early development of RLL, on an initially satisfying radiograph, is secondary to changes to the cement-bone interface. These are most often related to micromotion because of constraint, malalignment, remaining mechanical deformity, erroneous bone cuts or osteoporosis. This type of RLL are observed progressively on follow-up radiographs and can be accompanied by pain complaints despite of initial good outcome. Young age, male sex or osteoporotic bones often found in elderly females, are all risk factors. A special form of aseptic loosening is tibial debonding that has been observed for different types of implants and different types of cement. It occurs at the cement-implant interface with cement remaining well attached to the trabecular bone. Probably it is a lack of cement adhesion between the high viscosity cement and the component. Revision is proposed upon diagnosis to avoid component's displacement with secondary destruction of the proximal tibial bone. Finally, RLL can develop over time secondary to polyethylene wear. These lines appear because of osteolysis and bone loss and will lead at the end to aseptic loosening of the components. Symptoms are related to failure of the implant-bone construct. Radiolucent lines without clinical symptoms should be analysed according to their potential reason of development and followed up closely with adequate radiological techniques. If symptoms develop or radiological imaging objectivizes failure and component mobility, revision knee arthroplasty might be necessary.

Unicompartmental Knee Arthroplasty: US and Global Perspectives.

Unicompartmental knee arthroplasty (UKA) is a treatment option for anteromedial osteoarthritis. Compared with total knee arthroplasty (TKA), UKA offers improved knee range of motion, functional recovery and decreased medical complications. Revision rates continue to be higher with UKA compared with TKA. With current UKA implants, there is no significant difference in mobile bearing or fixed bearing, or between cemented and cementless implants. Enabling technology, such as robotic-assisted surgery, has demonstrated improvements in component positioning, but no long-term difference in survival compared with traditional manual instruments.

Dislocation of modern design rotating hinge total knee arthroplasty : case series and narrative review.

Knee dislocation is an infrequent complication after rotating hinge total knee arthroplasty (RHTKA). The aim of the present study was to describe our experience with dislocating RHTKA in a consecutive prospective large series, its occurrence rate, causative mechanisms and to perform a review of available literature. In total, six dislocations were observed in 303 RHTKA procedures (NexGen RHK, ZimmerBiomet, Warsaw, Indiana, US) at a mean of 10 (range, 2 - 24) months after surgery. This results in a 2% dislocation rate, which is lower than the 3.1% cumulative rate reported earlier in literature. Men and women were distributed equally, with a mean age of 56 years old. The indication for RHTKA among the six dislocations was revision in 4 cases and primary arthroplasty for the other 2 cases. Analysis revealed that the main mechanism of hinge dislocation was forced knee flexion with concomitant extensor mechanism insufficiency (4/6 cases). The second cause was unscrewing of the locking pin (2/6 cases). This is probably caused by the screw home mechanism that results in a counterclockwise torque -and therefore a loosening- effect on locking bolts, specifically in right-sided RHTKA. Obesity probably predisposes to hinge dislocation since 83% of patients in this series were obese (BMI, range 34 to 52). The findings of this study suggest that dislocation of RHTKA is a rare complication that could happen to obsese patients without an adequate extensor mechanism. Level of evidence : IV.

Distribution of sensory nerves supplying the knee joint capsule and implications for genicular blockade and radiofrequency ablation: an anatomical study.

BACKGROUND: Despite their emerging therapeutic relevance, there are many discrepancies in anatomical description and terminology of the articular nerves supplying the human knee capsule. This cadaveric study aimed to determine their origin, trajectory, relationship and landmarks for therapeutic purpose. METHODS: We dissected 21 lower limbs from 21 cadavers, to investigate the anatomical distribution of all the articular nerves supplying the knee joint capsule. We identified constant genicular nerves according to their anatomical landmarks at their entering point to knee capsule and inserted Kirschner wires through the nerves in underlying bone at those target points. Measurements were taken, and both antero-posterior and lateral radiographs were obtained. RESULTS: The nerve to vastus medialis, saphenous nerve, anterior branch of obturator nerve and a branch from sciatic nerve provide substantial innervation to the medial knee capsule and retinaculum. The sciatic nerve and the nerve to the vastus lateralis supply sensory innervation to the supero-lateral aspect of the knee joint while the fibular nerve supplies its infero-lateral quadrant. Tibial nerve and posterior branch of obturator nerve supply posterior aspect of knee capsule. According to our findings, five constant genicular nerves with accurate landmarks could be targeted for therapeutic purpose. CONCLUSION: The pattern of distribution of sensitive nerves supplying the knee joint capsule allows accurate and safe targeting of five constant genicular nerves for therapeutic purpose. This study provides robust anatomical foundations for genicular nerve blockade and radiofrequency ablation.

Comparison of local infiltration analgesia with single injection femoral nerve block in total knee arthroplasty.

The purpose of this study was to compare the analgesic and hemostatic effects of Local Infiltration Analgesia (LIA) with single injection femoral nerve block (SFNB). A database of patients undergoing knee arthroplasty between 2008 and 2013 was analyzed. A group of patients who underwent minimally invasive TKA either with SFNB (n = 112) or with LIA (n = 112) were matched. In the early postoperative period, the LIA group had a significantly lower VAS score, a lower drop in Hb and a lower length of hospital stay. Both the SFNB and LIA techniques provide excellent pain relief following TKA. Nevertheless, LIA reduces pain better in the very early postoperative period by a more complete nerve blockade allowing immediate postoperative mobilization and ambulation leading to a shorter hospital stay. Furthermore, LIA decreases perioperative blood loss by its local hemostatic effect.