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.

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.

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.

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%).

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.

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.

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.

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.

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.

Rotational Laxity Control by the Anterolateral Ligament and the Lateral Meniscus Is Dependent on Knee Flexion Angle: A Cadaveric Biomechanical Study.

BACKGROUND: Injury to the anterolateral ligament (ALL) has been reported to contribute to high-grade anterolateral laxity after anterior cruciate ligament (ACL) injury. Failure to address ALL injury has been suggested as a cause of persistent rotational laxity after ACL reconstruction. Lateral meniscus posterior root (LMPR) tears have also been shown to cause increased internal rotation of the knee. QUESTIONS/PURPOSES: The purpose of this study was to determine the functional relationship between the ALL and LMPR in the control of internal rotation of the ACL-deficient knee. Specifically: (1) We asked if there was a difference in internal rotation among: the intact knee; the ACL-deficient knee; the ACL/ALL-deficient knee; the ACL/LMPR-deficient knee; and the ACL/ALL/LMPR-deficient knee. (2) We also asked if there was a difference in anterior translation among these conditions. METHODS: Sixteen fresh frozen cadaveric knee specimens (eight men, mean age 79 years) were potted into a hip simulator (femur) and a 6 degree-of-freedom load cell (tibia). Rigid optical trackers were inserted into the proximal femur and distal tibia, allowing for the motion of the tibia with respect to the femur to be tracked during biomechanical tests. A series of points on the femur and tibia were digitized to create bone coordinate systems that were used to calculate internal rotation and anterior translation. Biomechanical testing involved applying a 5-Nm internal rotation moment to the tibia from full extension to 90° of flexion. Anterior translation was performed by applying a 90-N anterior load using a tensiometer. Both tests were performed in 15° increments tested sequentially in the following conditions: (1) intact; and (2) ACL injury (ACL-). The specimens were then randomized to either have the ALL sectioned (3) first (M+/ALL-); or (4) the LMPR sectioned first (M-/ALL+) followed by the other structure (M-/ALL-). A one-way analysis of variance was performed for each sectioning condition at each angle of knee flexion (α = 0.05). RESULTS: At 0° of flexion there was an effect of tissue sectioning such that internal rotation of the M-/ALL- condition was greater than ACL- by 1.24° (p = 0.03; 95% confidence interval [CI], 0.16-2.70) and the intact condition by 2.5° (p = 0.01; 95% CI, 0.69-3.91). In addition, the mean (SD) internal rotations for the M+/ALL- (9.99° [5.39°]) and M-/ALL+ (12.05° [5.34°]) were greater by 0.87° (p = 0.04; 95% CI, 0.13-3.83) and by 2.15°, respectively, compared with the intact knee. At 45° the internal rotation for the ACL- (19.15° [9.49°]), M+/ALL- (23.70° [7.00°]), and M-/ALL- (18.80° [8.27°]) conditions was different than the intact (12.78° [9.23°]) condition by 6.37° (p = 0.02; 95% CI, 1.37-11.41), 8.47° (p < 0.01; 95% CI, 3.94-13.00), and 6.02° (p = 0.01; 95% CI, 1.73-10.31), respectively. At 75° there was a 10.11° difference (p < 0.01; 95% CI, 5.20-15.01) in internal rotation between the intact (13.96° [5.34°]) and the M+/ALL- (23.22° [4.46°]) conditions. There was also a 4.08° difference (p = 0.01; 95% CI, 1.14-7.01) between the intact and M-/ALL- (18.05° [7.31°]) conditions. Internal rotation differences of 6.17° and 5.43° were observed between ACL- (16.28° [6.44°]) and M+/ALL- (p < 0.01; 95% CI, 2.45-9.89) as well as between M+/ALL- and M-/ALL- (p = 0.01; 95% CI, -8.17 to -1.63). Throughout the range of flexion, there was no difference in anterior translation with progressive section of the ACL, meniscus, or ALL. CONCLUSIONS: The ALL and LMPR both play a role in aiding the ACL in controlling internal rotation laxity in vitro; however, these effects seem to be dependent on flexion angle. The ALL has a greater role in controlling internal rotation at flexion angles > 30o. The LMPR appears to have more of an effect on controlling rotation closer to extension. CLINICAL RELEVANCE: Injury to the ALL and/or LMPR may contribute to high-grade anterolateral laxity after ACL injury. The LMPR and the ALL, along with the iliotibial tract, appear to act in concert as secondary stabilizers of anterolateral rotation and could be considered as the "anterolateral corner" of the knee.

Total knee arthroplasty after varus distal femoral osteotomy vs native knee: similar results in a case control study.

PURPOSE: The aim of this study was to investigate the results of total knee arthroplasty (TKA) performed after varus distal femoral osteotomy (VrDFO), in comparison to a control group of TKAs performed as the primary intervention for arthrosis. Main hypothesis was that the medium term results for the two groups would be similar. METHODS: All TKAs performed after VrDFO were extracted from a single centre, prospective database of 4046 arthroplasties. A case-control study was performed with a control group comprising two TKAs performed as the primary intervention for each TKA after VrDFO, and matched for sex, age at intervention, body mass index, the type of arthrosis and the type of implant. All prostheses used a system of posterior stabilisation by a third median condyle (Laboritoire Tornier-Wright). The primary outcome measure was the post-operative Knee Society Score (KSS). RESULTS: Fourteen TKAs after VrDFO were identified, with a median follow-up of 42 months (12-102 months). The control group comprised 28 patients. There were no significant differences between groups in terms of the matching criteria. Pre-operatively, there were no differences between groups in terms of KSS (knee and function scores), range of motion (fixed-flexion and maximum flexion), and mechanical axes on long leg films. Operative duration was identical for the two groups. In the VrDFO group there was more lateral intra-operative laxity (p = 0.006), more intra-operative complications (patella tendon injuries, p = 0.0008), and more frequent need for screw support for the tibial component due to more severe lower limb deformity (p < 0.0001). No significant difference was found between groups with regards to the post-operative KSS; median knee score was 91.7 in the VrDFO group compared to 82.3 in the control group, and function score 70.6 compared to 77.8. Range of motion was comparable between groups with median maximum flexion in the VrDFO group of 115.7° and 110.9° in the control group. CONCLUSION: TKAs after VrDFO is uncommon and can carry an increased risk of intra-operative complications. Despite this, the medium term results are comparable to arthroplasty performed as a primary intervention. TKA should not be denied to patients with previous femoral osteotomy, but care must be taken with gap balancing and axis correction. LEVEL OF EVIDENCE: 3.

Diagnostic findings caused by cutting of the iliotibial tract and anterolateral ligament in an ACL intact knee using a standardized and automated clinical knee examination.

PURPOSE: The purpose of this study was to evaluate the separate contribution of the two definitions of the anterolateral ligament (ALL), the mid-third lateral capsular ligament (MTLCL) and deep capsule-osseous layer of the iliotibial tract (dcITT) in addition to the superficial iliotibial tract (sITT) to the control of tibial motion with respect to the femur during the application of force/torque seen during the three tests of the standard clinical knee examination (AP Lachman test, tibial axial rotation test and varus-valgus stress test). METHODS: Six pelvis-to-toe cadaveric specimens were examined using an automated testing device that carried out the three components of the clinical knee examination. Internal/external rotation torque, anteroposterior load and adduction/abduction torque were applied, while torque/force and positional measurements were recorded. Sequential sectioning of the structures followed the same order for each knee, sITT, dcITT and MTLCL. Testing was repeated after release of each structure. RESULTS: During the tibial axial rotation test, releasing the sITT caused an increase in internal rotation of 2.6° (1.4-4.1°, p < 0.0005), while release of the dcITT increased internal rotation an additional 0.8° (0.4-1.1°, p < 0.0015). Changes in secondary motions of the tibia after sITT release demonstrated an increase in anterior translation of 1.2 mm (0.6-2.0 mm, p < 0.0005) during internal rotation, while release of the dcITT increased the same motion an additional 0.4 mm (0.2-0.5 mm, p < 0.0005). During the AP Lachman test, release of the sITT caused the tibia to move more anteriorly by 0.7 mm (0.4-1.1 mm, p < 0.0005) and increased internal rotation by 2.7° (0.9-5.2°, p < 0.004). The additional release of the dcITT resulted in more anterior translation by 0.3 mm (0.1-0.4 mm, p < 0.002) and internal rotation by 0.9° (0.2-1.7°, p < 0.005). During the varus-valgus stress test, release of the sITT permitted 0.9° (0.4-1.4°, p < 0.0005) more adduction of the tibia, while the additional release of the dcITT significantly increased adduction by 0.4° (0.2°-0.5°, p < 0.001). Release of the MTLCL had a nominal but significant increase in internal rotation, 0.6° (0.1-1.1°, p < 0.0068) and external rotation, -0.1° (-0.1° to -0.2°, p < 0.0025) during the tibial axial rotation test, anterior translation of 0.2 mm (0.0-0.4 mm, p < 0.021) only during the AP Lachman test, and adduction rotation, 0.2° (0.0-0.3°, p < 0.034) only during the varus-valgus stress test. CONCLUSION: The presence of increased adduction during an automated knee examination provides unique information identifying the release of the sITT, dcITT and the MTLCL in this cadaveric study. While their sequential release caused similar pattern changes in the three components of the automated knee examination, the extent of change due to release of the MTLCL was markedly less than after release of the dcITT which was markedly less than after release of the sITT.

Proximal tibial bony and meniscal slopes are higher in ACL injured subjects than controls: a comparative MRI study.

PURPOSE: Increased tibial slope is reported as a risk factor of non-contact anterior cruciate ligament (ACL) injury, but the effect of the soft tissues on slope remains unclear. The primary aims of this study were to compare the tibial bony and soft tissue slopes between patients with and without ACL injury, and to investigate the relationship between the meniscal slopes (MS) and the tibial bony slope. Our hypothesis was that the menisci would correct the inclination of the bony tibial slope towards the horizontal. METHODS: Using magnetic resonance imaging (MRI), the lateral and medial tibial slopes (LTS, MTS) and lateral and medial meniscal slopes (LMS, MMS) were compared in 100 patients with isolated ACL injury and a control group of 100 patients with patello-femoral pain and an intact ACL. RESULTS: Repeated-measures analysis of variance showed good inter- and intra-observer reliability for both bony and soft tissue slopes (ICC (0.88-0.93) and (0.78-0.91) for intra- and inter-observer reliability, respectively). The LTS and MTS were significantly greater in the ACL injury group (10.4 ± 3.1 and 9.4 ± 3.3) than in the control group (7.3 ± 3.4 and 7.0 ± 3.7). Similarly, the LMS and MMS were significantly greater in the ACL injury group (4.7 ± 4.7 and 6.0 ± 3.4) than the control group (0.9 ± 4.8 and 3.7 ± 3.6). In both groups, the lateral bony tibial slope was greater than the medial bony tibial slope, but the medial soft tissue slope was greater than the lateral soft tissue slope. CONCLUSION: Increased tibial slopes, both bony and meniscal, are risk factors for ACL injury. As the meniscus tends to correct the observed slope towards the horizontal, loss of the posterior meniscus may potentiate this effect by increasing the functional slope. LEVEL OF EVIDENCE: 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).

Posteromedial meniscal tears may be missed during anterior cruciate ligament reconstruction.

PURPOSE: This study aimed to assess the benefit of using an arthroscopic intercondylar view and a posterior medial viewing portal during anterior cruciate ligament (ACL) reconstruction in the diagnosis of posterior horn of the medial meniscus (PHMM) tears. A secondary objective was to determine clinical and radiological risk factors for the PHMM. METHODS: Forty-one patients undergoing isolated ACL reconstruction were prospectively evaluated. At ACL reconstruction, the PHMM was assessed using a standard 30° arthroscope in 3 sequential stages: a "classic" anterolateral portal view, an intercondylar view, and a view through a posteromedial portal. RESULTS: Thirty-nine patients were included (12 female patients and 27 male patients). A posteromedial tear of the medial meniscus was found in 17 patients using the anterolateral portal view. The intercondylar view identified 4 new additional lesions and extensions of 3 previously identified lesions. The posteromedial portal view identified 6 new lesions and 5 extensions of known lesions compared with the anterolateral portal view. Two lesions seen through the posteromedial portal were not identified by either the anterolateral portal view or the intercondylar view. CONCLUSIONS: Tears of the PHMM may be underdiagnosed by intraoperative assessment using only an anterolateral portal view during ACL reconstruction. The intercondylar view combined with a posteromedial portal aids in the diagnosis of PHMM tears and should be considered in routine ACL reconstruction to assess meniscal status, particularly when the interval from injury to surgery is prolonged. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Single-bundle ACL reconstruction with and without extra-articular reconstruction: evaluation with robotic lower leg rotation testing and patient satisfaction scores.

PURPOSE: The purpose of this study was to compare the biomechanical characteristics and patient outcomes after either isolated intraarticular ACL reconstruction or intraarticular reconstruction with lateral extra-articular tenodesis. In addition, we aimed to evaluate biomechanical parameters of the entire uninjured, contralateral knee as a baseline during the analysis. METHODS: Eighteen patients were evaluated at an average of 9.3 years after ACL reconstruction. Twelve patients had an intraarticular reconstruction (BTB), and six had an additional lateral extraarticular procedure (BTB/EAR). Patients were selected for the additional procedure by the operating surgeon based on clinical and radiological criteria. At the time of review, each patient was assessed using subjective patient questionnaires, manual laxity testing, and instrumented laxity testing. Each knee was also evaluated using a robotic lower leg axial rotation testing system. This system measured maximum internal and external rotations at 5.65 Nm of applied torque and generated load deformation curves and compliance data. Pointwise statistical comparisons within each group and between groups were performed using the appropriate paired or unpaired t test. Features were extracted from each load deformation curve for comparative analysis. RESULTS: There were no significant differences between the two groups with respect to the patient satisfaction scores or to laxity testing (manual or instrumented). Robotic testing results for within-group comparisons demonstrated a significant reduction in maximum external rotation (8.77°) in the reconstructed leg when compared to the healthy leg (p < 0.05) in the BTB/EAR group, with a non-significant change in internal rotation. The slope of the curve at maximum internal rotation was also significantly greater in the reconstructed legs for the BTB/EAR group (p < 0.05), indicating reduced endpoint compliance or a harder endpoint. Finally, the leg that received the extra-articular tenodesis had a trend towards a reduced total leg axial rotation. Conversely, patients in the BTB group demonstrated no significant differences between their legs. For between-group comparisons, there was a significant increase in maximum internal rotation in the healthy legs in the BTB/EAR group compared with the healthy legs in the BTB group (p < 0.05). If the injured/reconstructed legs were compared, the significant difference at maximum internal rotation disappeared (p < 0.10). Similarly, the healthy legs in patients in the BTB/EAR group had a significantly more compliant or softer endpoint in internal rotation, greater maximum internal rotation, and more internal rotation at torque 0 in their healthy legs compared with the healthy legs in the BTB group (p < 0.05). These same differences were not noted in the reconstructed knees. The only identifiable significant difference between the injured/reconstructed legs was rotation at 0 torque (p < 0.05). CONCLUSIONS: In this group of patients who were at an average of 9 years from surgery, the addition of a lateral extra-articular reconstruction to a standard bone-tendon-bone intraarticular ACL reconstruction does reduces internal rotation of the tibia with respect to the femur when compared to intraarticular reconstruction alone. It appears that the selection process for inclusion into the BTB/EAR group included an increase in total axial rotation of the healthy knee during the examination along with a decrease in endpoint stiffness at maximum internal rotation. LEVEL OF EVIDENCE: II.