Less risk of conversion to total knee arthroplasty without significant clinical and survivorship difference for opening-wedge high tibial osteotomies in varus knee deformities at 10-year minimum follow-up compared to closing-wedge high tibial osteotomies.

PURPOSE: The purpose of this study was to evaluate the clinical outcomes and survivorship at minimum 10-year follow-up of patients undergoing primary valgisation high tibial osteotomy (HTO) for medial osteoarthritis (OA), treated by Opening-Wedge HTO (OW-HTO) or Closing-Wedge HTO (CW-HTO). METHODS: This was a retrospective cohort study of consecutive patients presenting to a single institution undergoing HTO for isolated medial compartment OA. Two hundred and twenty three HTOs for isolated medial tibio-femoral OA were performed between January 2002 and December 2010. Patients were eligible if they had minimum 10-year follow-up and received either a CW or OW-HTO. Fifteen (6.7%) patients died and twenty-five (11.2%) were lost to follow-up. One hundred and eighty three (82.1%) patients were included in the final analysis and divided into two groups: OW-HTO (96/183; 52.4%) and CW-HTO (87/183; 47.6%). Range of motion, KSS, KOOS scores, and conversion to TKA rate were analyzed between groups. Both groups were comparable regarding age, arthrosis stage, gender, ASA score and BMI at the time of HTO. Survival analysis was conducted with re-intervention for TKA as the end point. RESULTS: At the time of HTO, mean age was 55 years ± 7.9 (27-73.9) with 72.7% of patients being male. The mean follow-up was 13.3 years ± 2.7 (10-19). Sixty-four (34.9%) patients underwent TKA at a mean delay of 9.3 years ± 3 (3-16). The conversion to TKA rate was significantly higher in the CW-HTO group versus the OW-HTO group: 42.5% (37/87) versus 28.1% (27/96) (p = 0.04). The survival at 15-year follow-up was 59.2% in the OW-HTO group versus 54.6% in the CW-HTO group (n.s.). At 13-year follow-up, KSS Function score was significantly better in the OW-HTO (90.9 versus 82.4; p = 0.007). No significant difference was observed between the two groups regarding the KOOS score, KSS Knee Score and complication rate. CONCLUSION: At mean follow-up of 13 years, no significant clinical and survivorship difference was observed between the two groups. The conversion to TKA was significantly lower following OW-HTO. Minor correction was associated with risk of requiring subsequent TKA. LEVEL OF EVIDENCE: Retrospective case series, IV.

No significant clinical and radiological differences between fixed versus mobile bearing total knee replacement using the same semi-constrained implant type: a randomized controlled trial with mean 10 years follow-up.

PURPOSE: The aim of this study was to compare the long-term clinical and radiological results between fixed (FB) and mobile bearing (MB) implants with identical design from the same manufacturer. METHODS: From March 2007 to May 2009, we recruited 160 patients in a prospective, single centered, randomized controlled trial. The authors compared 81 FB total knee arthroplasty (TKA) versus 79 MB with medial compartment osteoarthritis. The same posterior stabilized HLS Noetos knee prosthesis (CORIN) was used in all patients. The two groups only differed by the tibial insert (fixed or mobile). The authors compared the postoperative Knee Society Score (KSS), the passive clinical and active radiological knee flexion, the implant survivorship, the complications, and the presence of radiolucent lines. RESULTS: At mean 10.5 years' follow-up (range 8-12.1 years) no significant differences were found in clinical scores (KSS (p = 0.54), pain score (p = 0.77), stair climbing (p = 0.44), passive maximum flexion (p = 0.5)) or for radiological analyses (maximum active radiological flexion (p = 0.06), presence of progressive radiolucent lines (5 (MB group) versus 6 (FB group); p = 0.75)) between groups. No significant difference was found in overall implant survivorship (82% (MB group) versus 78% (FB group) p = 0.58) or complication rate (p = 0.32) at the last follow-up. CONCLUSION: No significant clinical and radiological differences were found between fixed and mobile bearing TKA using the same semi-constrained implant type with comparable overall survivorship. The choice between a fixed or mobile bearing implant should be based on surgeon preference and experience with the selected implant. LEVEL OF EVIDENCE: Prospective randomized controlled trial, Level II.

Early complications and causes of revision after rotating-hinge TKA.

INTRODUCTION: The use of rotating-hinge total knee arthroplasties (TKA), despite several developments in prosthetic design, remains controversial. Results as well as indications of these devices are still discussed in primary intention and for young patients. The aim was to analyze early complications and survival rate of rotating-hinge TKA in primary intention and for revisions. METHODS: A retrospective study included all the patients operated for primary or revision TKA procedure using a rotating-hinge TKA between 2015 and 2018. Clinical and radiological data were collected before surgery and then at a minimum follow-up of 1 year. The primary endpoint was the aseptic revision-free survival rate. Secondary endpoints were the overall survival rate, IKS scores, range of motion and patellar complications. RESULTS: Forty patients were included at an average follow-up of 18 months. Primary implantation was performed for 12 patients (30%), and revision for 28 cases (70%). At a mean follow-up of 18 months, only one implant was removed for a septic cause. The cumulative survival rate at 24 months was 95%. At final review, eight knees (20%) had been revised, five (12.5%) due to infection, two (5%) because of extensor mechanism failure, two (5%) for global stiffness. The objective and subjective IKS were significantly higher postoperatively in both primary and revision groups (p < 0.0001). Patellar height was significantly smaller after revision (p = 0.04), while ROM significantly improved in this group (p = 0.02). At final endpoint, one implant was removed for a septic cause. CONCLUSION: This rotating-hinge TKA provides satisfying clinical and functional outcomes in primary intentions and in revision cases. There was no implant-associated complication. The complication rate remains high for revision surgery cases, mostly due to previous joint infections and poor soft tissue quality causing extensor mechanism failure. A longer-term study should be conducted to confirm this trend.

Combined ACL reconstruction and opening wedge high tibial osteotomy at 10-year follow-up: excellent laxity control but uncertain return to high level sport.

PURPOSE: The purpose of this study was to report the long-term outcomes of a continuous series of patients who underwent simultaneous anterior cruciate ligament (ACL) reconstruction and opening wedge high tibial osteotomy (HTO) for varus-related early medial tibio-femoral osteoarthritis. It was hypothesized that this combined surgery sustainably allowed return to sport with efficient clinical and radiological results. METHODS: From 1995 to 2015, all combined ACL reconstruction (bone-patellar tendon-bone graft) and opening wedge HTO for anterior laxity and early medial arthritis were included. Clinical evaluation at final follow-up used Tegner activity score, Lysholm score, subjective and objective IKDC scores. Radiologic evaluation consisted in full-length, standing, hip-to-ankle X-rays, monopodal weight-bearing X-rays and skyline views. AP laxity assessment used Telos™ at 150 N load. Student's t test was performed for matched parametric data, Wilcoxon for nonparametric variables and Friedman test was used to compare small cohorts, with p < 0.05. RESULTS: 35 Patients (36 knees) were reviewed with a mean follow-up of 10 ± 5.2 years. The mean age at surgery was 39 ± 9. At final follow-up 28 patients (80%) returned to sport (IKDC ≥ B): 11 patients (31%) returned to sport at the same level and 6 (17%) to competitive sports. Mean subjective IKDC and Lysholm scores were 71.8 ± 14.9 and 82 ± 14.1, respectively. The mean decrease of the Tegner activity level from preinjury state to follow-up was 0.8 (p < 0.01). Mean side-to-side difference in anterior tibial translation was 5.1 ± 3.8 mm. Three patients were considered as failures. The mean preoperative mechanical axis was 4.2° ± 2.6° varus and 0.8° ± 2.7° valgus at follow-up. Osteoarthritis progression for medial, lateral, and femoro-patellar compartments was recorded for 12 (33%, p < 0.05), 6 (17%, p < 0.001), and 8 (22%, p < 0.05) knees, respectively. No femoro-tibial osteoarthritis progression was observed in 22 knees (61%). CONCLUSIONS: Combined ACL reconstruction and opening wedge HTO allowed sustainable stabilization of the knee at 10-year follow-up. However, return to sport at the same level was possible just for one-third of patients, with femoro-tibial osteoarthritis progression in 39% of cases. LEVEL OF EVIDENCE: III.

Combined Patellar Tendon lengthening and partial Extensor Mechanism Allograft reconstruction for the treatment of patella infera: A case report.

Patella infera is an uncommon but potentially crippling pathology of the knee, resulting in stiffness and anterior knee pain. Several surgical methods have been described for its treatment, but there remains no clear technique of choice. We present the case of a 63-year-old male with patella infera, affecting a native knee, following Complex Regional Pain Syndrome. This patient was treated with a combined technique of Patellar Tendon lengthening and partial Hourglass Extensor Mechanism Allograft reconstruction. The results were excellent at 24 months of follow-up. To our knowledge, this technique has not yet been published, and we present it as a promising treatment option in selected cases.

Increased valgus laxity in flexion with greater tibial resection depth following total knee arthroplasty.

PURPOSE: Soft tissue balancing is of central importance to outcome following total knee arthroplasty (TKA). However, there are lack of data analysing the effect of tibial bone cut thickness on valgus laxity. A cadaveric study was undertaken to assess the biomechanical consequences of tibial resection depth on through range knee joint valgus stability. We aimed to establish a maximum tibial resection depth, beyond which medial collateral ligament balancing becomes challenging, and a constrained implant should be considered. METHODS: Eleven cadaveric specimens were included for analysis. The biomechanical effects of increasing tibial resection were studied, with bone cuts made at 6, 10, 14, 18 and 24 mm from the lateral tibial articular surface. A computer navigation system was used to perform the tibial resection and to measure the valgus laxity resulting from a torque of 10 Nm. Measurements were taken in four knee positions: 0° or extension, 30°, 60° and 90° of flexion. Intra-observer reliability was assessed. A minimum sample size of eight cadavers was necessary. Statistical analysis was performed using a nonparametric Spearman's ranking correlation matrix at the different stages: in extension, at 30°, 60° and 90° of knee flexion. Significance was set at p < 0.05. RESULTS: There was no macroscopic injury to the dMCL or sMCL in any of the specimens during tibial resection. There was no significant correlation found between the degree of valgus laxity and the thickness of the tibial cut with the knee in extension. There was a statistically significant correlation between valgus laxity and the thickness of the tibial cut in all other knee flexion positions: 30° (p < 0.0001), 60° (p < 0.001) and 90° (p < 0.0001). We identified greater than 5° of valgus laxity, at 90° of knee flexion, after a tibial resection of 14 mm. CONCLUSION: Increased tibial resection depth is associated with significantly greater valgus laxity when tested in positions from 30° to 90° of flexion, despite stability in extension. Greater than 5° of laxity was identified with a tibial resection of 14 mm. When a tibial bone cut of 14 mm or greater is necessary, as may occur with severe preoperative coronal plane deformity, it is recommended to consider the use of a constrained knee prosthesis.

Faster return to sport after robotic-assisted lateral unicompartmental knee arthroplasty: a comparative study.

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) is frequently performed on active patients with symptomatic osteoarthritis who desire a quick return to sports. The aim of this study was to compare return to sport after lateral UKA performed by robotic-assisted and conventional techniques. MATERIALS AND METHODS: This retrospective study has assessed 28 lateral UKA (25 patients), 11 performed with robotic-assisted technique and 17 with conventional technique, between 2012 and 2016. The mean age was 65.5 and 59.5 years, with a mean follow-up of 34.4 months (range 15-50) and 39.3 months (range 22-68). Both groups were comparable pre-operatively. Sport habits and the details of the return to sports were assessed using University of California, Los Angeles Scale (UCLA) and direct questioning. RESULTS: Robotic-assisted surgical technique provided significantly quicker return to sports than conventional technique (4.2 ±1.8 months; range 1-6 vs 10.5 ± 6.7 months; range 3-24; p < 0.01), with a comparable rate of return to sports (100% vs 94%). The practiced sports after lateral UKA were similar to those done preoperatively, with mainly low- and mid-impact sports (hiking, cycling, swimming, and skiing). CONCLUSION: Robotic-assisted lateral UKA reduces the time to return to sports at pre-symptomatic levels when compared with conventional surgical technique. The return to sports rate after surgery is high in both groups. A long-term study would provide data on the prothesis wear in this active population. LEVEL OF EVIDENCE: Comparative retrospective study, Level III.

Complications and revision surgeries in two extra-articular tenodesis techniques associated to anterior cruciate ligament reconstruction. A case-control study.

INTRODUCTION: Numerous techniques of anterior cruciate ligament (ACL) reconstruction associated to extra-articular tenodesis (EAT) have been described, but there have been few comparative studies, especially in terms of complications and revision procedures. The present study sought to compare two ACL reconstruction techniques using the patellar tendon (KJ): associating EAT by fascia lata (KJL2) or by gracilis (KJG). The study hypothesis was that the KJL2 technique incurs no extra risk of complications or surgical revision compared to the KJG technique. METHOD: A prospective case-control study compared 41 patients undergoing KJL2 and 41 controls undergoing KJG. Complications, reconstruction failure and revision procedures were assessed at a mean 13 months follow-up (range, 6-20 months). RESULTS: The KJL2 group showed no extra risk of postoperative complications or reconstruction failure compared to the KJG group: 1 versus 2 re-tears, respectively, not requiring revision. Revision surgery was significantly more frequent in the KJG group (31.7% vs. 7.3%), notably for arthrolysis and meniscectomy. DISCUSSION: The KJL2 technique is reliable, without greater risk of complications or early revision surgery than the KJG technique. LEVEL OF EVIDENCE: III - Case-control study.

Non-compliance with IDSA guidelines for patients presenting with methicillin-susceptible Staphylococcus aureus prosthetic joint infection is a risk factor for treatment failure.

OBJECTIVE: The long-term impact of treatment strategies proposed by the IDSA guidelines for patients presenting with methicillin-susceptible S. aureus (MSSA) prosthetic joint infection (PJI) is not well-known. PATIENTS AND METHODS: Retrospective (2000-2010) cohort study including patients presenting with MSSA hip or knee PJI. A univariate Cox analysis was performed to determine if the non-compliance with IDSA surgical guidelines was a risk factor for treatment failure. RESULTS: Eighty-nine patients with a mean follow-up of 2.8 years were included. Non-compliance with IDSA surgical guidelines was associated with treatment failure (hazard ratio 2.157; 95% CI [1.022-4.7]). The American Society of Anesthesiologists score, inadequate antimicrobial therapy, and a rifampicin-based regimen did not significantly influence patient outcome. CONCLUSION: Based on the IDSA guidelines, if a patient presenting with MSSA PJI is not eligible for implant retention, complete implant removal is needed to limit treatment failure.

Intercalary diaphyseal endoprosthetic reconstruction for tibial septic non-union in an elderly patient: A case report.

The surgical treatment of septic non-union is challenging and carries a high failure rate. Bone defect management and fracture site stabilisation are key treatment objectives. We report the case of a 75-year-old woman who underwent intercalary endoprosthetic reconstruction of a large tibial defect due to septic non-union after two previous treatment failures. The two-stage procedure involved extensive excision of infected tissues and implantation of an antibiotic-loaded cement spacer followed by insertion of an intercalary endoprosthesis. Within only 2 months after the procedure, the patient was able to walk with no assistive device and no limp. After 12 months and 6 months after antibiotic discontinuation, the laboratory tests and imaging studies showed no evidence of infection. Intercalary endoprosthetic reconstruction may be a valid treatment option to avoid amputation for recurrent septic non-union, particularly in elderly patients.

Reconstructing the chronically disrupted knee extensor mechanism after total knee arthroplasty: Hourglass variant of the original partial allograft technique.

Allograft reconstruction is a valuable treatment option for patients with chronic extensor mechanism disruption after total knee arthroplasty. Here, an hourglass variant of the original partial allograft technique is described. An hourglass-shaped patellar bone block is press-fit into the native patella. The graft is fixed to both the patella and the tibia then sutured with the knee fully extended. Outcomes of this technique were assessed in 5 patients after at least 24months' follow-up. The mean knee and function Knee Society Score values were 77.8 and 64.0, respectively. Extension lag was less than 10 in all 5 patients. This hourglass variant of the partial allograft technique is a useful treatment option that can be used even after patellar resurfacing.

Arthroscopically assisted fixation is a reliable option for patellar fractures: A literature review.

Proper reduction and stable fixation of articular fractures is essential for an early recovery and to avoid late complications. Arthroscopically assisted techniques for minimally invasive fixation have been introduced to reduce local morbidity and improve anatomic reduction of the fragments. However up to date no clear indications for surgery have been given. In addition, the precise rates of functional outcomes and complications are controversial. The hypothesis was the systematic analysis of the available literature would provide precise indications, outcomes and complications of arthroscopically assisted techniques for patellar fracture fixation. A comprehensive literature review was performed using the keywords "patellar fracture", "arthroscopy" with no limit regarding the year of publication. All the selected articles were in English language and were evaluated with the Coleman score by three independent surgeons. The interclass correlation coefficient between the three examiners was calculated. Six full text articles were retrieved. The initial cohort included 60 patients with a displaced transverse fracture in the majority of the cases. At an average FU of 27.2 months the Lysholm score was 91.3. The rate of complication was 7%; Average Coleman score for the three observers was 55.8±6.5 with an ICC of 0.89, indicating adequate inter-rater agreement. Arthroscopically assisted techniques for minimally invasive fixation of patellar fractures represent a reliable option. The positive clinical outcomes and low rates of complications must be confirmed with further studies including larger series and longer FU. LEVEL OF EVIDENCE: Level IV, systematic review of retrospective series.

Total knee implant posterior stabilised by a third condyle: Design evolution and post-operative complications.

BACKGROUND: Despite excellent long-term outcomes, posterior stabilisation by a third condyle continues to receive unwarranted criticism regarding patellar complications and instability. HYPOTHESIS: Complication rates with a tri-condylar posterior-stabilised implant are similar to those with other posterior-stabilised prostheses and have diminished over time due to improvements in prosthesis design. MATERIAL AND METHODS: Post-operative complications and revision rates were assessed retrospectively in a prospective cohort of 4189 consecutive patients who had primary total knee arthroplasty (TKA) using a tri-condylar posterior-stabilised implant (Wright-Tornier) and were then followed-up for at least 24 months. The analysis included 2844 knees. The prosthesis generations were HLS1®, n=20; HLS2®, n=220; HLS Evolution®, n=636; HLS Noetos®, n=1373; and HLS KneeTec®, n=595. Complications were compared across generations by applying Fisher's exact test, and survival was compared using the Kaplan-Meier method. RESULTS: At last follow-up, there had been 341 (12%) post-operative complications in 306 (10.8%) knees, including 168 (5.9%) related to the implant, 41 (1.4%) infections, and 132 (4.6%) secondary complications unrelated to the implant. Re-operation was required for 200 complications (7%), including 87 (3.1%) consisting in revision of the prosthesis. Implant-related complications were stiffness (n=67, 2.4%), patellar fracture (n=34, 1.2%), patellar clunk syndrome (n=25, 0.9%), patellar loosening (n=3, 0.1%), tibial/femoral loosening (n=15, 0.5%), polyethylene wear (n=3, 0.1%), and implant rupture (n=1, 0.04%). Significant differences across generations were found for stiffness (P<0.0001), patellar fracture (P=0.03), clunk syndrome (P=0.03), and polyethylene wear (P=0.004), whose frequencies declined from one generation to the next. Overall 10-year survival was 92% with no significant difference across generations (P=0.1). DISCUSSION: Outcomes of tri-condylar posterior-stabilised TKA are similar to those obtained using other posterior-stabilised implants. Neither patellar complications nor instability are more common, and improvements in implant design have contributed to correct early flaws. LEVEL OF EVIDENCE: IV, historical cohort, retrospective assessment of prospectively collected data.

CT assessment of femoral tunnel placement after partial ACL reconstruction.

INTRODUCTION: When one of the anterior cruciate ligament (ACL) bundles is torn, it seems appropriate to preserve the remaining bundle to improve the vascularization and proprioception of the graft, and to reproduce the attachment sites of the torn bundle. After ACL reconstruction, the functional result is worse when the tunnels are positioned further away from the native ACL's isometric attachment points. The goal of this study was to use CT 3D reconstructions to analyse the position of the femoral tunnel following partial ACL reconstruction and to compare it to complete ACL reconstruction cases. We hypothesized that the femoral tunnel positioning was optimal during partial ACL reconstruction. METHODS: In this prospective single-centre study, 16 patients who underwent isolated anteromedial bundle reconstruction were evaluated during the immediate postoperative period using 3D reconstruction of CT images. During this same period, 180 patients who underwent complete ACL reconstruction in the same surgery unit served as a control group. RESULTS: In the partial ACL reconstruction group, 6 tunnels (37.5%) were in the optimal position and 10 tunnels (62.5%) were not. In the complete ACL reconstruction group, 124 femoral (68.9%) were in the optimal position and 56 (31.1%) were not (P<0.05). DISCUSSION: Femoral tunnel positioning is not always optimal in patients who undergo partial ACL reconstruction. Three-dimensional CT reconstruction is a good tool to help surgeons detect and learn from their errors. LEVEL OF EVIDENCE: III (case-control study).

Three-step sequential management for knee arthroplasty after severe ballistic injury: Two cases.

Management of knee bone loss after gunshot trauma requires a multidisciplinary approach. Two cases of knee arthroplasty after devastating ballistic trauma are reported. Treatment comprised several steps: sampling, bone resection, reinforced cement spacer, latent sepsis control, and prosthetic reconstruction. The patients showed no neurovascular disorder and had a functioning extensor mechanism. At follow-up of at least 2 years, results were satisfactory, with return to unaided walking and mean International Knee Society (IKS) score improved from 18 to 59 points. In light of these observations, knee reconstruction arthroplasty using a sequential strategy can provide satisfactory functional outcome after severe ballistic trauma.

The effect of lateral opening wedge distal femoral osteotomy on leg length.

PURPOSE: Varisation distal femoral osteotomy is a well-described treatment for lateral compartment arthrosis in the young, active patient. This treatment may potentially alter the length of the lower limb . The objective of this study was to quantify the change in leg length following lateral opening wedge distal femoral osteotomy using a blade plate. METHODS: Between 1998 and 2011, 29 lateral opening wedge distal femoral osteotomies were performed for symptomatic genu valgum with signs of lateral compartment arthrosis or patello-femoral symptoms. The mean age was 44.4 years (±11.3). Average follow-up was 80.2 months (±50.6). RESULTS: The mean osteotomy opening was 8.3° (±2.3). The femoro-tibial mechanical axis (mFTA) was improved significantly, from 187.8° (±3.5) to 180.4° (±2.6) post-operatively (p < 0.001). The pre-operative leg length discrepancy was -0.7 cm, compared to -0.6 cm post-operatively, which was not significant (n.s.). There were five revisions to arthroplasty for disease progression at meantime of 166.6 months post-operatively. The probability of survival at 60 months was 91.4% (95% CI 74.9-100%) with end-point of revision to total knee arthroplasty and 87.6% (95% CI 74.1-100%) of revision for complications. CONCLUSIONS: Lateral opening wedge distal femoral osteotomy, performed for symptomatic genu valgum, has no effect on leg length. This technique allows good correction of the axis of the lower limb; however, the complication rate is not insignificant (14%). Complications occurred mainly in post-traumatic cases and may be avoidable with attention to technique and optimum rehabilitation. The procedure should be reserved for young, active patients with significant symptoms. LEVEL OF EVIDENCE: IV.

Hypoxia potentiates the BMP-2 driven COL2A1 stimulation in human articular chondrocytes via p38 MAPK.

OBJECTIVE: Since the biological effect of cartilage mediators is generally studied in a non-physiologic environment of 21% O2, we investigated the effects of a chronic hypoxia on the capability of articular chondrocytes to respond to one anabolic stimulation. DESIGN: Human Articular Chondrocytes (HACs) were cultured under hypoxia and stimulated with the chondrogenic growth factor BMP-2. The phenotype of the chondrocytes was studied by RT-PCR, and the cartilage-specific type II collagen production and deposition were also examined by western immunoblot and immunofluorescence. The Bone Morphogenetic protein (BMP) signalling pathway was also analysed. RESULTS: BMP-2 is much more efficient to stimulate the expression of the cartilage-specific gene COL2A1 by HACs when cultured under hypoxia (1%O2) compared to normoxia (21%O2). Analysis of the BMP-activated signalling shows that the Smad pathway is inhibited under hypoxia, whereas p38 MAPK is activated, and is involved in a synergy between hypoxia and BMP signalling, thus contributing to the enhanced anabolic response. CONCLUSIONS: Our study shows that hypoxia interplays with a chondrogenic factor and enhances the overall anabolic activity of the HACs. Alternatively to Hypoxia-Inducible Factor (HIF) signalling, and through a cross-talk with the BMP signalling which involves the p38 pathway, hypoxic stimulation markedly increases the capability of chondrocytes to produce the cartilage-specific type II collagen. Therefore our study provides new evidences of the multilayered effects of hypoxia in the anabolic functions of chondrocytes. This understanding may help promoting the anabolic function of articular chondrocytes, and thus improving their manipulation for cell therapy.

The role of the meniscotibial ligament in posteromedial rotational knee stability.

PURPOSE: Tears of the posterior horn of the medial meniscus (PHMM) are very common in the ACL-deficient knee. Specific lesions of the PHMM have been described in the setting of ACL rupture: ramp lesions and injuries to the meniscotibial ligament. There are little data available regarding the role these lesions play in knee instability. The aim of this study is to analyse the biomechanical consequences of ramp and meniscotibial ligament lesions on knee stability. Our hypothesis was that these lesions would cause increased instability in the setting of ACL rupture. METHODS: A cadaveric study was undertaken: ten knees were included for analysis. The biomechanical repercussions of different meniscoligamentous injuries were studied in four stages: stage 1 involved testing the intact knee, stage 2 after transection of the ACL, stage 3 following creation of a ramp lesion, and stage 4 after detachment of the meniscotibial ligament. Four parameters were measured during the experiment: anterior tibial translation under a force of 134 N, internal and external tibial rotation under a torque of 5 Nm, and valgus angulation under a torque of 10 Nm. Measurements were taken in four knee flexion positions: 0° or full extension, 30°, 70°, and 90° of flexion. RESULTS: There was a statistically significant increase in anterior tibial translation for stage 2 (6.8 ± 1.3 mm, p ≤ 0.001), stage 3 (9.4 ± 1.3 mm, p ≤ 0.001), and stage 4 (9.3 ± 1.3 mm, p ≤ 0.001) compared to stage 1. There was no significant difference between stage 2 and stage 3 (2.6 mm, n.s.) or stage 4 (2.5 mm, n.s.). We did, however, demonstrate an increase in anterior tibial translation of 2.6 mm after the creation on a lesion of the PHMM compared to isolated division of the ACL, for all flexion angles combined. There was an increase in internal tibial rotation between stage 1 and stage 4 (3.2° ± 0.7°, p ≤ 0.001) and between stage 2 and stage 4 (2.0° ± 0.7°, p = 0.023). A significant difference was demonstrated for external rotation under 5 Nm torque between stages 4 and 1 (2.2° ± 0.5°, p ≤ 0.001) and between stages 4 and 2 (1.7° ± 0.5°, p = 0.007) for all knee flexion angles combined. No created lesion had a significant effect on medial laxity under a 10-Nm valgus torque at any degree of knee flexion. CONCLUSION: Lesions of the posterior horn of the medial meniscus are frequent in cases of anterior cruciate ligament rupture. These lesions appear to play a significant role in knee stability. Ramp lesions increase the forces in the ACL, and the PHMM is a secondary restraint to anterior tibial translation. Lesions of the meniscotibial ligament may increase rotatory instability of the knee.

The role of high tibial osteotomy in the treatment of knee laxity: a comprehensive review.

PURPOSE: The purpose of this study is to review the indications for and outcomes of high tibial osteotomy in the treatment of patients with chronic knee laxity. METHODS: A comprehensive literature review was performed to identify surgical indications and results of high tibial osteotomy for the treatment of chronic knee laxity. RESULTS: Four distinct situations were identified in which a high tibial osteotomy may be advantageous: (1) anterior laxity with varus osteoarthritis, (2) chronic anterior laxity in the setting of varus with lateral ligamentous laxity, (3) chronic anterior laxity in the setting of a high tibial slope, and (4) chronic posterior laxity or posterolateral corner injury. A total of 24 studies were included in this report, including reports of the treatment of 410 knees as well as several review articles. The most frequently reported indication for that addition of HTO was anterior laxity in the setting of varus OA, which was noted to have good results, minimizing anterior knee laxity and allowing return to sports, while reducing the progression of osteoarthritis. More advanced cases in which lateral structures have also become stretched and incompetent are an excellent indication for HTO, with the need for subsequent lateral procedures dependent on the degree of varus laxity and especially hyperextension that is present. Excessive tibial slope has been identified as a cause of ACL reconstruction failure, and some authors have recommended addressing very high slope in revision cases. In knees with chronic posterior or posterolateral instability, correction of alignment first is generally recommended, with subsequent ligamentous procedures performed when instability persists. CONCLUSIONS: Knees with chronic instability pose a difficult treatment challenge. In all cases, the contribution of coronal plane alignment to varus-valgus knee stability must be carefully considered and addressed prior to ligament surgery. Sagittal plane alignment is also key and must not be overlooked. Such considerations drive the indication for osteotomy as well as the type of osteotomy that is chosen. Level of evidence IV.

Gait changes of the ACL-deficient knee 3D kinematic assessment.

PURPOSE: Static, one-dimensional testing cannot predict the behaviour of the anterior cruciate ligament (ACL)-deficient knee under realistic loading conditions. Currently, the most widely accepted method for assessing joint movement patterns is gait analysis. The purpose of the study was in vivo evaluation of the behaviour of the anterior cruciate ligament-deficient (ACLD) knees during walking, using 3D, real-time assessment tool. METHODS: Biomechanical data were collected prospectively on 30 patients with ACL rupture and 15 healthy subjects as a control group, with KneeKg™ System. Kinematic data were recorded in vivo during treadmill walking at self-selected speed. Flexion/extension, abduction/adduction, anterior/posterior tibial translation and external/internal tibial rotation were compared between groups. RESULTS: The ACLD patients showed a significant lower extension of the knee joint during stance phase (p < 0.05; 13.2° ± 2.1° and 7.3° ± 2.7°, for ACLD and control group, respectively). A significant difference in tibial rotation angle was found in ACLD knees compared to control knees (p < 0.05). The patients with ACLD rotated the tibia more internally (-1.4° ± 0.2°) during the mid-stance phase, than control group (0.2° ± 0.3°). There was no significant difference in anteroposterior translation and adduction-abduction angles. CONCLUSION: Significant alterations of joint kinematics in the ACLD knee were revealed in this study by manifesting a higher flexion gait strategy and excessive internal tibial rotation during walking that could result in a more rapid cartilage thinning throughout the knee. The preoperative data obtained in this study will be useful to understand the post-ACL reconstruction kinematic behaviour of the knee. CLINICAL RELEVANCE: The findings in this study indicate that ACLD knee may adapt functionally to prevent excessive anterior-posterior translation but they fail to avoid rotational instability.