How often do we need offset stems for revision total knee arthroplasty? About a consecutive series of 789 knees.

INTRODUCTION: This study aimed to determine the incidence of offset stem usage in revision total knee arthroplasty (rTKA), and to assess the necessity for their use with the femoral and tibial components. METHODS: This retrospective radiological study included 862 patients who underwent rTKA between 2010 and 2022. Patients were divided into a non-stem group (group NS), offset stem group (group OS), and straight stem group (group SS). Two senior orthopedic surgeons evaluated all the post-operative radiographs of the group OS to assess the necessity of offset use. RESULTS: In total, 789 patients met all eligibility inclusion criteria and were reviewed (305 males (38.7%)) with a mean age of 72.7 ± 10.2 years old [39; 96]. Eighty-eight (11.1%) patients had undergone rTKA with offset stems (34 tibia, 31 femur, 24 both) and 609 (70.2%) with straight stems. The tibial and femoral stems were diaphyseal of over 75 mm in 83 revisions (94.3%) for group OS and 444 revisions (72.9%) for group SS (p < 0.001). Offset in the tibial component was located medially in 50% of rTKA, while the offset in the femoral component was placed anteriorly in 47.3% of the rTKA. Assessment by the two independent senior surgeons found stems were only necessary in 3.4% of cases. Offset stems were only required for the tibial implant. DISCUSSION: Offset stems were used in 11.1% of revision total knee replacements, however, they were deemed necessary in 3.4% and for the tibial component only.

Review of Cha et al. (2005) on "Arthroscopic Double Bundle Anterior Cruciate Ligament Reconstruction: An Anatomical Approach".

This classic discusses the original publication 'Arthroscopic double-bundle anterior cruciate ligament reconstruction (ACL): An anatomical approach', the first detailed description of the surgical technique popularised by Dr Freddie Fu. The technique, in which the anteromedial and posterolateral bundles of the ACL are reconstructed individually using two grafts with independent bone tunnels, was designed to more closely recreate the function of the native ACL by more closely reproducing the functional anatomy. This reconstruction was biomechanically superior to single-bundle reconstruction, particularly with regards to rotational control, leading to great interest from ACL surgeons around the world. Clinical superiority was more difficult to demonstrate; however, and the technical difficulty of the procedure has limited its use. Nevertheless, the pursuit of improved patient outcomes through attention to functional anatomical detail continues. 'Recreating the functional anatomy of the intact ACL remains the cornerstone of ACL reconstruction'.

No difference of gait parameters in patients with image-free robotic-assisted medial unicompartmental knee arthroplasty compared to a conventional technique: early results of a randomized controlled trial.

PURPOSE: In recent studies, robotic-assisted surgical techniques for unicompartmental knee arthroplasty (UKA) have demonstrated superior implant positioning and limb alignment compared to a conventional technique. However, the impact of the robotic-assisted technique on clinical and functional outcomes is less clear. The aim of this study was to compare the gait parameters of UKA performed with conventional and image-free robotic-assisted techniques. METHODS: This prospective, single-center study included 66 medial UKA, randomized to a robotic-assisted (n = 33) or conventional technique (n = 33). Gait knee kinematics was assessed on a treadmill at 6 months to identify changes in gait characteristics (walking speed, each degree-of-freedom: flexion-extension, abduction-adduction, internal-external rotation, and anterior-posterior displacement). Clinical results were assessed at 6 months using the IKS score and the Forgotten Joint Score. Implants position was assessed on post-operative radiographs. RESULTS: Post-operatively, the whole gait cycle was not significantly different between groups. In both groups, there was a significant improvement in varus deformity between the pre- and post-operative gait cycle. There was no significant difference between the two groups in clinical scores, implant position, revision, and complication rates. CONCLUSION: No difference of gait parameters could be identified between medial UKA performed with image-free robotic-assisted technique or with conventional technique. LEVEL OF EVIDENCE: Prospective randomized controlled trial.

Femorotibial alignment measured during robotic assisted knee surgery is reliable: radiologic and gait analysis.

PURPOSE: Femorotibial alignment is crucial for the outcome of unicompartmental knee arthroplasty (UKA). Robotic-assisted systems are useful to increase the accuracy of alignment in UKA. However, no study has assessed if the femorotibial alignment measured by the image-free robotic system is reliable. The aim of this study was to determine whether measurement of the mechanical femorotibial axis (mFTA) in the coronal plane with handheld robotic assistance during surgery is equivalent to a static measurement on radiographs and to a dynamic measurement during walking. METHODS: Twenty patients scheduled for robotic-assisted medial UKA using handheld technology were included in this prospective study. Three measurements of the frontal femorotibial axis were compared: intra-operative acquisition by computer assistance (dynamic, non-weightbearing position), radiographic measurements on long leg X-ray (static, weightbearing position), and by gait analysis during walking (dynamic, weightbearing position). RESULTS: There was no significant difference in the mFTA between computer (174.4 ± 3.4°), radiological (173.9 ± 3.3°), and gait analysis (172.9 ± 5.1°) measurements (p = 0.5). There was a strong positive correlation (r = 0.6577355, p = 0.0016) between robotic-assisted measurements and gait analysis. CONCLUSION: There was no significant difference in the femorotibial axis measured by the image-free robotic assistance, from the preoperative radiographs or by gait analysis. The reliability of intra-operative measurements of the frontal femorotibial axis by these robotic-assisted systems is acceptable.

Health economic value of CT scan based robotic assisted UKA: a systematic review of comparative studies.

PURPOSE: The aim of this systematic review was to compare relevant health economic consequences of the CT-based robotic-arm-assisted system versus conventional Uni-compartmental Knee Arthroplasty (UKA). METHODS: In November 2020, A PRISMA systematic review was conducted using four databases (Pubmed, Scopus, Cochrane and Google Scholar) to identify all comparative studies reporting health economic assessments, such as robotic system costs, consumable costs, surgical revision rate, operating time, length of stay, and inpatient care costs. RESULTS: A total of nine comparative studies published between 2014 and 2020 were included in this systematic review. There was a moderate risk of bias as assessed using the ROBINS-I Tool. The CT-based robotic-arm-assisted system seemed to be associated with a lower risk of revision, decreased analgesia requirements during hospitalization, a shorter length of stay, and lower inpatient care costs compared to a conventional technique. CONCLUSION: CT-based robotic-arm-assisted system for UKA appears to be an economically viable solution with a positive health economic impact as it tends to decrease revision rate compared to conventional UKA, improve post-operative rehabilitation and analgesia management. Post-operative inpatient care costs seem lower with the robotic-assisted system but depend on institutional case volume and differ among health systems. More studies are needed to confirm cost-effectiveness of CT-based robotic-arm-assisted system based on different health systems. LEVEL OF EVIDENCE: Systematic review, Level IV.

Predictive Models for Clinical Outcomes in Total Knee Arthroplasty: A Systematic Analysis.

BACKGROUND: Predictive modeling promises to improve our understanding of what variables influence patient satisfaction after total knee arthroplasty (TKA). The purpose of this article was to systematically review the relevant literature using predictive models of clinical outcomes after TKA. The aim was to identify the predictor strategies used for systematic data collection with the highest likelihood of success in predicting clinical outcomes. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol systematic review was conducted using 3 databases (MEDLINE, EMBASE, and PubMed) to identify all clinical studies that had used predictive models or that assessed predictive features for outcomes after TKA between 1996 and 2020. The ROBINS-I tool was used to evaluate the quality of the studies and the risk of bias. RESULTS: A total of 75 studies were identified of which 48 met our inclusion criteria. Preoperative predictive factors strongly associated with postoperative clinical outcomes were knee pain, knee-specific Patient-Reported Outcome Measure (PROM) scores, and mental health scores. Demographic characteristics, pre-existing comorbidities, and knee alignment had an inconsistent association with outcomes. The outcome measures that correlated best with the predictive models were improvement of PROM scores, pain scores, and patient satisfaction. CONCLUSIONS: Several algorithms, based on PROM improvement, patient satisfaction, or pain after TKA, have been developed to improve decision-making regarding both indications for surgery and surgical strategy. Functional features such as preoperative pain and PROM scores were highly predictive for clinical outcomes after TKA. Some variables such as demographics data or knee alignment were less strongly correlated with TKA outcomes. LEVEL OF EVIDENCE: Systematic review - Level III.

Improved sizing with image-based robotic-assisted system compared to image-free and conventional techniques in medial unicompartmental knee arthroplasty.

AIMS: Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique. METHODS: Three groups of 93 medial UKAs were assessed. The first group was performed by a conventional technique, the second group with an image-free robotic-assisted system (Image-Free group), and the last group with an image-based robotic arm-assisted system, using a preoperative CT scan (Image-Based group). There were no demographic differences between groups. We compared six parameters on postoperative radiographs to assess UKA sizing. Incorrect sizing was defined by an over- or under-sizing greater than 3 mm. RESULTS: There was a higher rate of tibial under-sizing posteriorly in the conventional group compared to robotic-assisted groups (47.3% (n = 44) in conventional group, 29% (n = 27) in Image-Free group, 6.5% (n = 6) in Image-Based group; p < 0.001), as well as a higher rate of femoral under-sizing posteriorly (30.1% (n = 28) in conventional group, 7.5% (n = 7) in Image-Free group, 12.9% (n = 12) in Image-Based group; p < 0.001). The posterior femoral offset was more often increased in the conventional group, especially in comparison to the Image-Based group (43% (n = 40) in conventional group, 30.1% (n = 28) in Image-Free group, 8.6% (n = 8) in Image-Based group; p < 0.001). There was no significant overhang of the femoral or tibial implant in any groups. CONCLUSION: Robotic-assisted surgical techniques for medial UKA decrease the risk of tibial and femoral under-sizing, particularly with an image-based system using a preoperative CT scan. Cite this article: Bone Joint J 2021;103-B(4):610-618.

Is robotic-assisted unicompartmental knee arthroplasty a safe procedure? A case control study.

PURPOSE: The hypotheses were that firstly there is few early specific complications due to the use of a robotic-assisted system for unicompartimental knee arthroplasty (UKA), and secondly there are less revisions and complications after robotic-assisted UKA than after conventional UKA. METHODS: 200 robotic-assisted UKA (175 patients) and 191 conventional UKA (179 patients) were performed between 2013 and 2018 from the same center. Revisions, intraoperative and postoperative complications, functional and radiological results were collected at the most recent follow-up. RESULTS: At the most recent follow-up (≥ 1 year), revision rates were 4% (n = 8/200) for robotic-assisted UKA and 11% (n = 21/191) for conventional UKA (p = 0.014). Reoperation rates without implant removal were comparable in the robotic and conventional group (7.3% vs 8.6%). Complication rates for stiffness (4.7% vs 4.2%) and infection (1% vs 1.6%) were comparable in both groups. There was no specific complication related to the robotic-assisted system (no soft tissue or bone lesion caused by the use of the robotic-assistance and no complication related to the use of navigation pins). The KSS function scores were higher following robotic-assisted UKA (p = 0.01). Satisfaction rates and contralateral OA were comparable in the two groups. CONCLUSION: No complications due to the robotic-assisted system were found in this study. There was no difference in the general complications rate between both groups. Robotic-assisted UKA has a lower revision rate compared to conventional technique UKA at the short-term follow-up. LEVEL OF EVIDENCE: III. CLINICAL RELEVANCE: This is the first paper comparing revision rate and clinical outcome between UKA performed using the NAVIO robotic system and a conventional technique and searching for specific complication related to the use of the NAVIO robotic system.

Lateral unicompartmental knee arthroplasty is a safe procedure for post-traumatic osteoarthritis after lateral tibial plateau fracture: a case-control study at 10-year follow-up.

PURPOSE: Very few studies focus on lateral unicompartmental arthroplasty (LUKA) in the setting of post-traumatic osteoarthritis (PTOA). The hypothesis of our study is that LUKA is an effective procedure for isolated lateral PTOA with similar outcomes to non-traumatic LUKA. METHODS: Between 1990 and 2016, eighteen LUKA performed for isolated lateral tibiofemoral osteoarthritis secondary to tibial plateau fracture were retrospectively reviewed (post-traumatic group) and matched with a control group of thirty-six LUKA performed for non-traumatic OA. Clinical (International Knee Score), radiological outcomes and revision rate were compared between the two groups with a minimum follow-up of three years. RESULTS: With a mean follow-up of 10.1 years, postoperative IKS scores were similar between the two groups (IKS Knee: 89.1 (control) versus 85 (p = 0.03) and IKS Function: 85.9 (control) versus 77.9 (n.s.). Clinical improvement was greater for the post-traumatic group. No difference was observed with regard to revision rate (3/18 (16.7%) cases in the post-traumatic group and 7/36 (19.4%) in the control group, n.s.) or polyethylene wear per year between the two groups. The revision free-survival rate was 64.8% for the post-traumatic group and 58.8% for the control group at 22-year follow-up (n.s.). CONCLUSION: LUKA is an effective procedure at long-term for patients suffering from isolated lateral PTOA with similar clinical and radiographic results compared to LUKA performed for non-traumatic OA and without increased risk of revision or prosthetic wear. LEVEL OF EVIDENCE: IV.

The posteromedial corner of the knee: an international expert consensus statement on diagnosis, classification, treatment, and rehabilitation.

PURPOSE: To establish recommendations for diagnosis, classification, treatment, and rehabilitation of posteromedial corner (PMC) knee injuries using a modified Delphi technique. METHODS: A list of statements concerning the diagnosis, classification, treatment and rehabilitation of PMC injuries was created by a working group of four individuals. Using a modified Delphi technique, a group of 35 surgeons with expertise in PMC injuries was surveyed, on three occasions, to establish consensus on the inclusion or exclusion of each statement. Experts were encouraged to propose further suggestions or modifications following each round. Pre-defined criteria were used to refine item lists after each survey. The final document included statements reaching consensus in round three. RESULTS: Thirty-five experts had a 100% response rate for all three rounds. A total of 53 items achieved over 75% consensus. The overall rate of consensus was 82.8%. Statements pertaining to PMC reconstruction and those regarding the treatment of combined cruciate and PMC injuries reached 100% consensus. Consensus was reached for 85.7% of the statements on anatomy of the PMC, 90% for those relating to diagnosis, 70% relating to classification, 64.3% relating to the treatment of isolated PMC injuries, and 83.3% relating to rehabilitation after PMC reconstruction. CONCLUSION: A modified Delphi technique was applied to generate an expert consensus statement concerning the diagnosis, classification, treatment, and rehabilitation practices for PMC injuries of the knee with high levels of expert agreement. Though the majority of statements pertaining to anatomy, diagnosis, and rehabilitation reached consensus, there remains inconsistency as to the optimal approach to treating isolated PMC injuries. Additionally, there is a need for improved PMC injury classification. LEVEL OF EVIDENCE: Level V.

Arthroscopic-Assisted Lower Trapezius Tendon Transfer for Massive Irreparable Posterosuperior Rotator Cuff Tears Using an Achilles Tendon-Bone Allograft.

The lower trapezius tendon (LTT) transfer has been described for the management of irreparable posterosuperior rotator cuff tears. Here we describe our technique of an arthroscopic-assisted LTT transfer using an Achilles tendon-bone allograft. This technique allows for augmentation of the tendon transfer using an Achilles tendon allograft while also keeping the calcaneal bone insertion, which allows for added bony fixation into the humerus and also minimizing the risk of the "killer turn" phenomenon at the aperture of fixation.

Why Reintervention After Total Knee Arthroplasty Fails? A Consecutive Cohort of 1170 Surgeries.

BACKGROUND: The aim of this study was to analyze why contemporary reintervention after total knee arthroplasty (RiTKA) fails. METHODS: Between January 2006 and December 2010, from a multicenter cohort of 1170 RiTKAs, we assessed all failures of RiTKA requiring additional surgery. All indications for the index reintervention were included. The minimum follow-up period was 3 years. RESULTS: A total of 192 (16.4%) patients required additional surgery after RiTKA (re-reintervention). The mean follow-up period was 7.7 years. Mean age was 69.2 years. The mean time to re-reintervention was 9.6 months with 90.1% of rTKA failure occurring within the first two years. Infection was the main cause of new surgery after RiTKA (47.9%; n = 92/192). Other causes included extensor mechanism pathology (14.6%), stiffness (13.5%), pain (6.8%), aseptic loosening (5.2%), laxity (5.2%), periprosthetic fracture (3.6%), and wound pathology (3.1%). In four groups, the main indication for re-reintervention was recurrence of the pathology leading to the first reintervention: RiTKA for infection (59/355, 16.6%, P < .05), stiffness (18/174, 10.3%, P < .05), extensor mechanism failure (9/167, 5.4%, P < .05), and RiTKA for pain (4/137, 2.9%, P = .003). Global survival curve analysis found 87.9% survivorship without re-reintervention at one year and 83% at eight years. CONCLUSION: Contemporary RiTKA failures mainly occur in the first two postoperative years. Infection is the main cause of failure in RiTKA. Recurrence of the initial pathology occurs in four groups of RiTKA and is the main indication for re-reintervention in these groups; infection (16.6%), stiffness (10.3%), extensor mechanism failure (5.4%), and pain (2.9%).

High Survival Rate and Very Low Wear of Lateral Unicompartmental Arthroplasty at Long Term: A Case Series of 54 Cases at a Mean Follow-Up of 17 Years.

BACKGROUND: Survivorship of lateral unicompartmental knee arthroplasty (UKA) has progressively improved. However, there are few studies describing long-term results, and no study reports on polyethylene (PE) wear in lateral unicompartmental arthroplasty. The aims of this study are to determine the survival rate of lateral UKA with a fixed, all-PE bearing, and the PE wear of the tibial implant at a minimum of 15 years follow-up. METHODS: From January 1988 to October 2003, we performed 54 lateral UKAs in 52 patients. All patients had isolated lateral osteoarthritis (OA). The mean age at the index procedure was 65.4 ± 11 years. Thirty-nine UKAs were available for follow-up (30 alive and 9 dead after 15 years). Twelve patients had died before 15 years and 3 patients were lost to follow-up. The mean follow-up was 17.9 years (range, 15-23 years). RESULTS: At the final follow-up, 8 knees of 39 (20.5%) had a surgical revision. The cumulative survival rate was 82.1% at 15 years and 79.4% at 20 years. The main reason of revision was progression of OA (87.5%), followed by aseptic loosening of the tibial component (12.5%). With a mean follow-up of 17.9 years, the mean PE wear was 0.061 mm/y. There was no radiographic loosening in the surviving implants and no revisions for wear. The mean functional International Knee Society score was 66.5 ± 26.8, with a mean objective score of 84.4 points ± 13.2. In the population without revision, 90.5% were satisfied or very satisfied at the latest follow-up. CONCLUSION: Lateral UKA with a fixed, all-PE tibial bearing and a femoral resurfacing implant presents a high survivorship at long term, with very low PE wear.

Posterolateral corner of the knee: an expert consensus statement on diagnosis, classification, treatment, and rehabilitation.

PURPOSE: To develop a statement on the diagnosis, classification, treatment, and rehabilitation concepts of posterolateral corner (PLC) injuries of the knee using a modified Delphi technique. METHODS: A working group of three individuals generated a list of statements relating to the diagnosis, classification, treatment, and rehabilitation of PLC injuries to form the basis of an initial survey for rating by an international group of experts. The PLC expert group (composed of 27 experts throughout the world) was surveyed on three occasions to establish consensus on the inclusion/exclusion of each item. In addition to rating agreement, experts were invited to propose further items for inclusion or to suggest modifications of existing items at each round. Pre-defined criteria were used to refine item lists after each survey. Statements reaching consensus in round three were included within the final consensus document. RESULTS: Twenty-seven experts (100% response rate) completed three rounds of surveys. After three rounds, 29 items achieved consensus with over 75% agreement and less than 5% disagreement. Consensus was reached in 92% of the statements relating to diagnosis of PLC injuries, 100% relating to classification, 70% relating to treatment and in 88% of items relating to rehabilitation statements, with an overall consensus of 81%. CONCLUSIONS: This study has established a consensus statement relating to the diagnosis, classification, treatment, and rehabilitation of PLC injuries. Further research is needed to develop updated classification systems, and better understand the role of non-invasive and minimally invasive approaches along with standardized rehabilitation protocols. LEVEL OF EVIDENCE: Consensus of expert opinion, Level V.

The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting.

The structure and function of the anterolateral complex (ALC) of the knee has created much controversy since the 're-discovery' of the anterolateral ligament (ALL) and its proposed role in aiding control of anterolateral rotatory laxity in the anterior cruciate ligament (ACL) injured knee. A group of surgeons and researchers prominent in the field gathered to produce consensus as to the anatomy and biomechanical properties of the ALC. The evidence for and against utilisation of ALC reconstruction was also discussed, generating a number of consensus statements by following a modified Delphi process. Key points include that the ALC consists of the superficial and deep aspects of the iliotibial tract with its Kaplan fibre attachments on the distal femur, along with the ALL, a capsular structure within the anterolateral capsule. A number of structures attach to the area of the Segond fracture including the capsule-osseous layer of the iliotibial band, the ALL and the anterior arm of the short head of biceps, and hence it is not clear which is responsible for this lesion. The ALC functions to provide anterolateral rotatory stability as a secondary stabiliser to the ACL. Whilst biomechanical studies have shown that these structures play an important role in controlling stability at the time of ACL reconstruction, the optimal surgical procedure has not yet been defined clinically. Concern remains that these procedures may cause constraint of motion, yet no clinical studies have demonstrated an increased risk of osteoarthritis development. Furthermore, clinical evidence is currently lacking to support clear indications for lateral extra-articular procedures as an augmentation to ACL reconstruction. The resulting statements and scientific rationale aim to inform readers on the most current thinking and identify areas of needed basic science and clinical research to help improve patient outcomes following ACL injury and subsequent reconstruction.Level of evidence V.

Clinical Results of Lateral Extra-Articular Tenodesis.

In the anterior cruciate ligament (ACL) deficient knee, excellent outcomes are achieved in many patients with an isolated, intra-articular ACL reconstruction. Some patients, however, have ongoing instability or suffer graft rupture. Failure after ACL reconstruction is multifactorial, but residual anterolateral rotatory laxity is 1 potential contributing factor. Lateral extra-articular procedures are a heterogenous group of operations that were initially described as isolated treatments for the ACL deficient knee, and subsequently used in combination with intra-articular reconstructions. Initial observational studies were encouraging, however, comparative studies were less flattering and lead to a general abandonment of these procedures. With improved understanding of the anatomy and biomechanics of the anterolateral capsuloligamentous complex there has been a renewed interest in these procedures. Recent systematic reviews suggest efficacy of these procedures in improving rotational control, though data showing improved patient reported outcomes or reduced graft rupture rates are lacking. Preliminary results from ongoing clinical trials are supportive for lateral extra-articular tenodesis when used as an augment to modern, intra-articular ACL reconstructions in targeted, high-risk patients.

Incidence and patterns of meniscal tears accompanying the anterior cruciate ligament injury: possible local and generalized risk factors.

AIM OF THE WORK: Injury to the anterior cruciate ligament (ACL) is frequently accompanied by tears of the menisci. Some of these tears occur at the time of injury, but others develop over time in the ACL-deficient knee. The aim of this study was to evaluate the effects of the patient characteristics, time from injury (TFI), and posterior tibial slope (PTS) on meniscal tear patterns. Our hypothesis was that meniscal tears would occur more frequently in ACL-deficient knees with increasing age, weight, TFI, PTS, and in male patients. METHODS: Of the ACL-injured patients, 362 were analyzed, and details of meniscal lesions were collected. The medial and lateral tibial slopes (MTS, LTS) were measured via computed tomography. Patient demographics, TFI, MTS, and LTS were correlated with the diagnosed meniscal tears. RESULTS: Of the patients, 113 had a medial meniscus (MM) tear, 54 patients had a lateral meniscus (LM) tear, 34 patients had tears of both menisci, and 161 patients had no meniscal tear. The most common tear location was the posterior horn (PH) of the MM, followed by tear involving the whole MM. Patient age, BMI, and TFI were significantly associated with the incidence of MM tear. Female patients had a higher incidence of injury than males in all tear sites except in the body and PH. Male patients had more vertical and peripheral tears. The median MTS and LTS for patients with MM tears were 7.0°and 8.7°, respectively, while those of patients with LM tears were 6.9° and 8.1°. Steeper LTS was significantly associated with tears of LM and of both menisci. CONCLUSION: Older age, male sex, increased BMI, and prolonged TFI were significant factors for the development of MM tears. An increase in the tibial slope, especially of the lateral plateau, seems to increase the risk of tear of the LM and of both menisci. LEVEL OF EVIDENCE: Level III.

Improved joint-line restitution in unicompartmental knee arthroplasty using a robotic-assisted surgical technique.

PURPOSE: Joint-line restitution is one objective of unicompartmental knee arthroplasty (UKA). However, the joint line is often lowered when resurfacing femoral implants are used. The aim of this study was to compare the joint-line height in UKA performed by robotic-assisted and conventional techniques. METHODS: This retrospective case-control study compared two matched groups of patients receiving a resurfacing UKA between 2013 and 2016 by either a robotic-assisted (n = 40) or conventional (n = 40) technique. Each group comprised 27 women and 13 menm wuth a mean age of 69 and 68 years, respectively. Indications for surgery were osteoarthritis (n = 35) and condylar osteonecrosis (n = 5). Two validated radiologic measurement methods were used to assess joint-line height. RESULTS: Forty UKA (23 medial and 17 lateral) were analysed in each group. Restitution of joint-line height was significantly improved in the robotic-assisted group compared than the control group: +1.4 mm ±2.6 vs +4.7 mm ± 2.4 (p < 0.05) as assessed using method 1, and +1.5 mm ±2.3 vs +4.6 mm ±2.5 (p < 0.05) as assessed using method 2. CONCLUSIONS: Restitution of joint-line height in resurfacing UKA can be improved with robotic-assisted surgery. Improvement in clinical outcome measures must be demonstrated with long-term studies.

Three dimensionalCT analysis of femoral tunnel position after ACL reconstruction. A prospective study of one hundred and thirty five cases.

BACKGROUND: One of the principal causes for failure of anterior cruciate ligament reconstruction (ACL) is femoral tunnel mal-position. Several studies compare the position of femoral tunnels achieved with various techniques, with small series and using a quadrant assessment method. QUESTIONS: (1) What is the incidence of anatomical positioning of the intra-articular femoral tunnel aperture in primary ACL reconstruction in a university knee surgery? (2) What are the main errors in positioning? METHODS: 3D-CT scans were performed after primary ACL reconstruction in 135 consecutive cases. The intra-articular position of the femoral tunnel aperture was analyzed using the Magnussen classification. RESULTS: The intra-articular tunnel position was deemed anatomical in 77%, intermediate in 20.8%, and non-anatomical in 2.2%. Among the mal-positioned tunnels, 54.8% were vertical, 29% were anteriorly positioned, and 16.1% were both. CONCLUSIONS: The intra articular femoral tunnel aperture was well positioned using an outside-in technique. The main error of tunnel positioning was a tunnel too vertical. LEVEL OF EVIDENCE: Level III, prospective study (case series).