Bicompartmental Knee Arthroplasty Research Articles

Systematic Review of Modular Bicompartmental Knee Arthroplasty for Medio-Patellofemoral Osteoarthritis

BackgroundWe aimed to locate, appraise, and synthesize the available literature to assess the functional outcome of modular bicompartmental knee arthroplasty (BKA) compared to total knee arthroplasty (TKA) for medio-patellofemoral osteoarthritis. MethodsAfter an extensive literature search based on electronic databases such as MEDLINE, EMBASE, CINAHL, and PubMed, and grey literature, 9 articles satisfied our selection criteria which included 1 randomized controlled trial, 1 prospective cohort, 3 retrospective cohort, and 4 case series. Narrative synthesis was performed due to clinical, methodological, and statistical heterogeneity among the included studies. ResultsThere were 331 participants (341 knees) in this systematic review. BKA group included 229 patients (239 knees) and TKA group included 102 patients (102 knees). The quality of included studies ranged from moderate to very low as per GRADE (grading of recommendations, assessment, development, and evaluation working group) score with low to high risk of bias. Most of the studies showed comparable functional outcome in BKA compared to TKA such as Knee Society Score, Knee Osteoarthritis and Outcome Score, Short Form-36 score, and revision surgery in short-term to midterm follow-up. BKA patients achieved better range of movement and forgotten knee status than TKA patients. It resulted in longer operative time, but less intraoperative blood loss. Long-term series showed 95.1% survivorship of BKA at 5 years and 58% at 17 years. ConclusionCurrent evidence suggests that modular BKA provides comparable functional outcome to TKA at short-term to midterm follow-up, however, with poor long-term survivorship.

Synovial Cytokines Significantly Correlate with Osteoarthritis-Related Knee Pain and Disability: Inflammatory Mediators of Potential Clinical Relevance.

The aim of this study was to identify inflammatory mediators of potential clinical relevance in synovial fluid (SF) samples of patients with knee osteoarthritis (OA). Therefore, radiographic OA severity, knee pain and function of 34 OA patients undergoing unicompartmental (UC) and bicompartmental (BC) knee arthroplasty were assessed prior to surgery and SF samples were analyzed for a broad variety of inflammatory mediators, including interleukins (ILs), interferons (IFNs), C-X-C motif ligand chemokines (CXCLs), and growth factors (nerve growth factor; NGF, vascular endothelial growth factor; VEGF, and stem cell growth factor β; SCGF-β) using multiplex assay. Significant differences were observed between the SF levels of different inflammatory markers. When compared to UC OA, significantly higher concentrations of IL-7, IL-8, IL-10, IL-12, IL-13, IFN-γ, VEGF and CXCL1 were detected in BC OA. Correlation analyses revealed significant associations between OA severity and IL-6, IL-8, IFN-γ, SCGF-β, VEGF, CXCL1. Interestingly, increases in both anti- (IL-10, IL-13) and pro-inflammatory (IL-7, IL-12, IFN-γ) cytokines, as well as growth factors (SCGF-β, VEGF), correlated significantly with the level of knee pain. Poorer knee function was associated with higher IL-6, IL-10, IL-12, IL-13, IL-18, βNGF, SCGF-β, VEGF and CXCL9 levels. In conclusion, this study provides an extensive profile of synovial inflammatory mediators in knee OA and identifies cytokines of potential clinical relevance. In fact, five of the mediators examined (IL-10, IL-12, IL-13, SCGF-β, VEGF) significantly correlate with both knee pain and function.

Customised bi-compartmental knee arthroplasty shows encouraging 3-year results: findings of a prospective, multicenter study.

The purpose of this study was to assess the clinical and patient-reported outcomes of a customised, individually made (CIM) bi-compartmental knee arthroplasty (BKA). A prospectively recruited cohort of 79 patients was implanted with a CIM-BKA (patello-femoral plus either medial or lateral tibio-femoral, iDuo G2 system, Conformis, Billerica MA) at eight centres in the US and Germany. Patients were assessed for the 2011 KSS, KOOS, and ROM pre-operatively and at 2weeks, 6weeks, 12weeks, 1 year, and 2 years post-operatively. The objective KSS score significantly improved from 69 at the pre-operative visit, to 94 at the 2-year post-operative time-point. Similar improvements were observed for the KSS function and satisfaction domains. Significant improvements from pre-operative levels were observed across all five domains of the KOOS. Two patients have undergone surgery to revise their CIM-BKA implant to total knees, resulting in a survivorship rate of 97.5% at an average follow-up of 2.6years. CIM-BKA compares favourably to published scores as well as revision rates for previously available monolithic OTS-BKA implants. CIM-BKA implants provide surgeons with a viable and patient-specific monolithic implant solution as an option for patients presenting with bi-compartmental disease, who might, otherwise, be treated by performing uni-condylar + patello-femoral joint or bicruciate sparing TKA surgeries. Longer follow-up and higher numbers have to be awaited for further validation of these encouraging early results. 3b (individual case-controlled study).

Bicompartmental Knee Arthroplasty (BKA) in comparison to unicompartmental (UKA), Patellofemoral (PFA) ans total knee arthroplasty (TKA) – Early Clinical Results

Aims and Objectives: The purpose was to evaluate the clinical outcomes of patients with knee osteoarthritis treated with bicompartmental arthroplasty (BKA) in comparison to unicompartmental (UKA), patellofemoral (PFA) and total knee arthroplasty (TKA) in a single center. Materials and Methods: This is a prospective study analyzing a consecutive series of 396 patients from two surgeons in a single center. In 191 men and 205 women either partial or total knee replacement were performed. Their mean age at surgery was 63±6,85 years and mean BMI 29,55±5,00 kg/m2. In 238 patients UKA, in 125 TKA, in 21 PFA and in 11 patients BKA was performed. Implants were cemented and made of cobalt chrome in partial knee and zirconium oxide in total knee replacement. Demographics and patient reported outcomes (VAS, KOOS, Oxford Knee Score (OKS)) were collected preoperatively and 3,6 and 12 months postoperatively. A total of 202 patients have thus far completed the 12 months follow-up time point. Results: All mean KOOS and OKS scores improved significantly 1 year after surgery (p<0.05). Mean preoperative aggregated KOOS improved from 49,0±14,1 to 74,3±17,8 in UKA, from 44,1±12,9 to 67,5±9,4 in PFA, from 46,1±15,1 to 71,0±14,8 in TKA and from 45,7±13,8 to 72,6±9,7 in BKA (p<0.05). Mean preoperative aggregated OKS improved from 25,1±7,6) to 38,5±9,7 in UKA, from 23,0±7,6 to 36,8±3,8 in PFA, from 23,4±8,2 to 37,3±8,1 in TKA and from 22,9±9,6 to 37,0±1,5 in BKA (p<0.05). The mean pain level (VAS)decreased from pre-treatment to 12 months after surgery in UKA from 5,5 to 1,6, in PFA from 6,1 to 2,5, in TKA from 6,0 to 1,9 and in BKA from 6,6 to 2,6. One patient (0.4%) underwent revision (at 3 month for inlay dislocation). Conclusion: This study shows excellent early clinical results of patients treated with unicompartmental, bicompartmental and total knee arthroplasty. Adherence to strict indications lead to a significant improvement of patient reported outcomes and a low revision rate one year postoperatively. The reported results for BKA are comparable to those of patients treated with unicompartmental arthroplasty. We conclude that bicompartmental arthroplasty is a safe and reliable surgery for patients with bicompartmental osteoarthritis.

Protesi bi-compartimentali di ginocchio: trend di utilizzo e analisi della letteratura

Minimally invasive surgery in knee arthroplasty has been a challenge since the 1950s, when the first mono-compartmental knee prostheses were implanted. The challenge was to treat the different osteoarthritis areas of the knee independently, saving soft tissue and healthy bones. Theoretically, bicompartmental knee arthroplasty (BKA) provides more physiological knee movement and the feeling of a “natural knee” compared to total knee replacement (TKA). Several prosthetic designs have been used with controversial results in the literature: although some authors have shown good functional results using BKA, a greater number of failures and complications have been detected than with TKA. In fact, to date, BKA is not recommended as a routine procedure, owing to the heterogeneity of studies and the lack of long-term follow-up studies. The purpose of this article was to clarify the use of bicompartmental knee arthroplasty (BKA). We have carried out a systematic literature review that includes 2 meta-analyses, 2 randomised controlled trials, 5 prospective controlled trials and international arthroplasty registries.

A high level of satisfaction after bicompartmental individualized knee arthroplasty with patient-specific implants and instruments

PurposeCustomized Individually Made (CIM) Bicompartmental Knee Arthroplasty (BKA) implants and three-dimensional printed customized instruments are available to fit to each patient’s unique anatomy, medial or lateral with patellofemoral. This study aimed to evaluate the clinical outcomes after CIM-BKA.MethodsFifty-five patients [59 knees; average age, 51 years; standard deviation (SD), 6.8; range 37–65 years] who underwent CIM-BKA were evaluated over an average of 3.8-year follow-up (SD 1.6; range 1–6 years). Forty-one knees underwent BKA combined medial and patellofemoral replacement (BKA-MP) and 18 knees underwent BKA combined lateral with patellofemoral replacement (BKA-LP). Survival rates, the modified Cincinnati Knee Rating Scale, WOMAC, VAS, SF-36, a satisfaction survey, and radiographic evaluation were used to evaluate outcomes.ResultsOverall, survival rates were 98% and 92% at 2 and 5 years, respectively. Of 56 knees (95%) that did not fail, all patient-reported functional scores significantly improved post-operatively (P < 0.01), regardless of the previous surgeries, with a high level of satisfaction (51/56 knees, 91%). Radiographically, all the femoral components fit perfectly and 56 knees (95%) of the tibial components fit with less than 2 mm of undercoverage or overhang. Three knees (5%) required the conversion to TKA and 17 knees (29%) required subsequent surgical procedures, of which multiply operated knees had higher rate than virgin knee [14/40 (35%) vs. 3/16 (19%)].ConclusionCIM-BKA allowed precise fit of the components and provided a significant improvement post-operatively with a high level of satisfaction over short- to mid-term follow-up. This novel CIM-BKA is resurfacing, and does not require 10-mm faceted cuts, being only 3-mm-thick, which preserves bone stock for the future. It may be a promising option for relatively young active patients with bicompartmental osteoarthritis with a longer term follow-up being necessary.Level of evidenceIV.

Evaluation of implant fit and frontal plane alignment after bi-compartmental knee arthroplasty using patient-specific instruments and implants.

IntroductionThe goals of successful bi-compartmental knee arthroplasty are to achieve correct fit and positioning of the implant, while appropriately correcting the mechanical alignment of the leg after surgery. As these requirements are not always reliably fulfilled using off-the-shelf implant systems, newer approaches for bi-compartmental resurfacing have been explored.Material and methodsIn this article we report the radiographic results of 30 patients with anteromedial osteoarthritis (OA) who were treated with a novel patient-specific fixed-bearing bi-compartmental knee resurfacing system using custom-made implants and instruments. Utilizing standardized pre- and postoperative radiographic analyses (based on anterior-posterior and lateral, anterior-posterior weight-bearing full-length radiographs, patella skyline views and preoperative computed tomography (CT) scanning) implant fit and positioning as well as correction of the mechanical axis (hip-knee-ankle angle, HKA) were determined.ResultsOn average, HKA was corrected from 173.4 ±3.47° preoperatively to 179.4 ±2.85° postoperatively. The coronal femoro-tibial angle was corrected on average 5.61°. The preoperative tibial slope measured on lateral views was 6.38 ±2.4°, while the average slope in the CT-based planning protocol (iView) was 6.14 ±2.40°. Postoperative lateral tibial slope was determined to be 5.77 ±1.97°. The thickness of the posterior femoral cuts was measured intraoperatively and, in all cases, corresponded well to the targeted thickness of the cuts provided by the iView. The joint line was preserved in all cases and the average Insall-Salvati index was 1.078 ±0.11 pre- and 1.072 ±0.11 postoperatively. The fit of the implant components measured by over- or underhang was excellent throughout (< 1.01 mm).ConclusionsCustom-made bicompartmental knee arthroplasty can ensure optimized fitting and positioning of the implant with restoration of the leg axis. These implants could be considered as an alternative primary solution for knee surgeons treating bi-compartmental disease.

Short term result of bicompartmental knee arthroplasty for osteoarthritis

Short term result of bicompartmental knee arthroplasty for osteoarthritis

Bicompartmental knee arthroplasty vs total knee arthroplasty for the treatment of medial compartment and patellofemoral osteoarthritis.

BackgroundInterest in bicompartmental knee arthroplasty (BKA) for the treatment of medial patellofemoral osteoarthritis (MPFOA) has grown in recent years because BKA offers a bone and ligament-preserving alternative to total knee arthroplasty (TKA). BKA only resurfaces the diseased compartments, while preserving proprioception and native knee kinematics. Therefore, the objective of this study is to assess knee function, perioperative morbidity, and implant survivability in patients undergoing BKA vs TKA for MPFOA.MethodsThe databases MEDLINE, PUBMED, and EMBASE were systematically searched. Randomized controlled trials and nonrandomized comparative studies comparing BKA with TKA for the treatment of MPFOA were included for further analysis. The primary outcome of interest was knee function. Secondary outcomes included range of movement, operation length, intraoperative blood loss, hospital length of stay, postoperative complications, and rate of revision length. The quality of evidence was evaluated using the GRADE approach. Meta-analysis was performed by pooling the results of the selected studies when possible.ResultsSix studies were selected for inclusion (4 prospective studies and 2 retrospective cohort studies). In total, 274 patients and 277 knees were included for analysis. There were no significant differences between the 2 groups at any time points in terms of knee function, length of stay, complication rate, or revision rate, when monolithic BKA designs were controlled for. BKA did result in significantly decreased intraoperative blood loss, at the expense of increased operative length compared with TKA.ConclusionsThe use of modular BKA for MPFOA is comparable with TKA in terms of short-term function, complication rate, and revision rate. BKA reduces intraoperative blood losses, but it is also more technically demanding, resulting in increased operation length. The use of modular BKA has acceptable short-term outcomes, but more long-term data are needed before it can be recommended for routine use in the treatment of MPFOA. The selection of modular BKA should be determined on a patient-specific basis. Currently, there is no evidence to suggest the use of monolithic BKA designs because of their high revision and failure rate.

Radiographic Imaging in the Postanesthesia Care Unit is Unnecessary After Partial Knee Arthroplasty

BackgroundObtaining routine radiographs in the postanesthesia care unit (PACU) after primary uncomplicated partial knee arthroplasty (PKA) is a common practice with unclear utility. The objective of this study is to determine the rate at which immediate postoperative radiographs identify an actionable problem after primary uncomplicated PKA and to determine the potential cost savings associated with foregoing the routine acquisition of these radiographs. MethodsThis was a retrospective review that assessed a consecutive series of 1366 primary uncomplicated PKAs (including 873 unicondylar knee arthroplasties, 313 patellofemoral arthroplasties, and 180 bicompartmental knee arthroplasties) performed between January 2008 and March 2016. Patients were separated into 2 cohorts: (1) those who had PACU radiographs (n = 1184), and (2) those who did not (n = 182). Operative reports and clinical follow-up records at the initial postoperative visit were reviewed to determine whether patients underwent early reoperation based on radiographic findings. The direct cost of PACU radiographs was estimated to be $33.63 based on average global Medicare payments from our institution. ResultsThe rate of reoperation because of radiographic findings in the PACU or at the first follow-up was 0% (95% confidence interval: 0.0%-0.027%). The estimated direct radiographic expenditure for our 1366 patient cohort was nearly $46,000. ConclusionRoutine immediate postoperative PACU radiographs after primary uncomplicated PKA have limited clinical utility. Therefore, delaying postoperative radiographs until the initial follow-up office visit would result in substantial cost-savings without compromising the quality of patient care.

Bicompartmental Knee Arthroplasty

Knee arthritis is one of the leading causes of disability and functional limitations in the United States and worldwide. Total knee arthroplasty results in good functional outcomes and high survival rates in patients who have tricompartmental arthritis. Bicompartmental knee arthroplasty is being used more often in patients who have arthritis that is isolated to two compartments: the patellofemoral compartment and either the medial or the lateral compartment. Bicompartmental knee arthroplasty preserves the kinematics, ligaments, and bone stock of the knee and is a good option for younger, active, high-demand patients who wish to return to their previous level of activity.

PS155 Effects of Ischemic Postconditioning on Sizes of Myocardial Infarction Induced by Ischemia/Reperfusion and Toll-R4 Expression in Rats

A significant proportion of patients with knee osteoarthritis have articular degeneration that is limited to the medial and patellofemoral compartments. The objective of this study was to compare clinical outcomes of unlinked bicompartmental knee arthroplasty (BCA) and total knee arthroplasty (TKA) at 5 years in this subset of patients.48 patients were randomised into two groups: unlinked, modular bicompartmental arthroplasty and total knee arthroplasty. Data on demographics and clinical outcomes were collected (Bartlett Knee Score, Oxford Knee Score, Knee Society Score). Data on intra-operative blood loss in both groups were also recorded.Out of the 48 patients, 26 underwent BCA and 22 had TKA. Both groups shared similar demographic profiles. At five years post surgery, there was significant improvement across all functional scores in both groups. However, there was no significant difference in outcome scores in the BCA group compared to the TKA group. The drop in serum haemoglobin levels postoperatively was 1.55 and 2.30 g/dl for the BCA and TKA groups respectively (p < .001). The total amount of blood loss was 397 and 647 ml respectively (p = .001).Unlinked, modular BCA results in similar clinical and functional scores as TKA for medial and patellofemoral arthritis in the mid-term. Intra-operative blood loss was significantly lower in the BCA group compared to the TKA group. BCA is a viable option for a select group of young and active patients with the advantage of reduced intra-operative blood loss and equivalent functional outcomes as TKA.

Routine Postoperative Laboratory Tests Are Unnecessary After Partial Knee Arthroplasty

BackgroundWhile partial knee arthroplasty (PKA) is increasingly performed on an outpatient basis, many surgeons still admit patients overnight and obtain laboratory studies on the first postoperative day. The purpose of this study was to investigate the utility and cost effectiveness of routine postoperative laboratory studies after PKA. MethodsThis is a retrospective review of 322 consecutive unilateral or bilateral simultaneous PKAs (unicompartmental, patellofemoral, and modular bicompartmental knee arthroplasty) performed by a single surgeon. There were 408 complete blood counts and basic metabolic panels ordered. ResultsDespite a large number of laboratory studies ordered and abnormalities detected, there was a 1.6% rate of laboratory-associated interventions (for either hypokalemia or hyperglycemia in 5 patients) and no red blood cell transfusions. Hospital charges associated with laboratory studies totaled $85,413. There were no 90-day postoperative hospital readmissions or emergency department evaluations related to abnormal postoperative laboratory values. ConclusionWith an increasing emphasis placed on cost containment, the low rate of laboratory-associated interventions after PKA suggests that routinely obtaining laboratory studies are neither necessary nor cost effective.

Early failure with the Journey-Deuce bicompartmental knee arthroplasty.

The aim of this study was to evaluate the early functional outcome and survivorship of a bicompartmental knee arthroplasty implant (Journey-Deuce) in a cohort of patients with combined medial and patellofemoral degenerative osteoarthritis. Fifteen patients with a mean age of 57years were followed up prospectively and evaluated with clinical examination, Oxford knee score and radiology imaging. Poor pain scores, concerns about the tibial fixation, early aseptic loosening of the tibial component and a revision rate of 60% at a minimum follow-up of 54months are reported. Implantation of this prosthesis was stopped at our institution well before the first revision due to an unfavourable early clinical response. This was further endorsed by an unacceptable revision rate. The outcome of the Journey-Deuce bicompartmental knee replacement was considerably worse than the published outcome of total knee replacement.

Bicompartmental knee arthroplasty.

Total knee arthroplasty (TKA) is the most worldwide practiced surgery for knee osteoarthritis and its efficacy is mightily described by literature. Concerns about the invasiveness of TKA let the introduction of segmental resurfacing of the joint for younger patients with localized osteoarthritis. Bone stock sparing and ligaments preservation are the essence of both unicompartmental knee arthroplasty (UKA) and bicompartmental knee arthroplasty (BKA). Advantages related to BKA are the respect of knee biomechanics, lower complications rates, shorter hospital stay, faster rehabilitation. Moreover, in case of failure of the first implant the conversion to TKA is undemanding and can be compared to a standard prosthesis. Our experience suggest that BKA is a reliable technique in selected cases and especially younger people with higher functional requests can favourably profit from it. Although those results are encouraging, we still need further prospective, randomized, long-term studies to finally assess BKA indications and outcomes.

Prospective randomised trial comparing unlinked, modular bicompartmental knee arthroplasty and total knee arthroplasty: A five years follow-up

BackgroundA significant proportion of patients with knee osteoarthritis have articular degeneration that is limited to the medial and patellofemoral compartments. The objective of this study was to compare clinical outcomes of unlinked bicompartmental knee arthroplasty (BCA) and total knee arthroplasty (TKA) at 5years in this subset of patients. Methods48 patients were randomised into two groups: unlinked, modular bicompartmental arthroplasty and total knee arthroplasty. Data on demographics and clinical outcomes were collected (Bartlett Knee Score, Oxford Knee Score, Knee Society Score). Data on intra-operative blood loss in both groups were also recorded. ResultsOut of the 48 patients, 26 underwent BCA and 22 had TKA. Both groups shared similar demographic profiles. At five years post surgery, there was significant improvement across all functional scores in both groups. However, there was no significant difference in outcome scores in the BCA group compared to the TKA group. The drop in serum haemoglobin levels postoperatively was 1.55 and 2.30g/dl for the BCA and TKA groups respectively (p<.001). The total amount of blood loss was 397 and 647ml respectively (p=.001). ConclusionsUnlinked, modular BCA results in similar clinical and functional scores as TKA for medial and patellofemoral arthritis in the mid-term. Intra-operative blood loss was significantly lower in the BCA group compared to the TKA group. BCA is a viable option for a select group of young and active patients with the advantage of reduced intra-operative blood loss and equivalent functional outcomes as TKA.

Retrospective Clinical and Radiological Outcomes after Robotic Assisted Bicompartmental Knee Arthroplasty.

Purpose. Bicompartmental knee arthroplasty (BiKA) is a favorable alternative to total knee arthroplasty for degenerative disease limited to two knee compartments. Recently developed robotic-assisted systems improved the clinical efficacy of unicompartmental knee arthroplasty by providing enhanced component positioning with dynamic ligament balancing. The purpose of this study was to evaluate the short-term outcomes of patients, undergoing bicompartmental knee arthroplasty at a single institution by a single surgeon using a robotic-assisted system. It was hypothesized that robotic assisted BiKA is a prevailing choice for degenerative disease limited to two knee compartments with good functional results. Methods. A search of the institution's joint registry was conducted to identify patients that underwent robotic-assisted BiKA of the patellofemoral compartment and the medial or lateral compartment. Results. A total number of 29 patients (30 BiKA) with a mean age of 63.6 years were identified who received a patellofemoral resurfacing in combination with medial or lateral compartment resurfacing. Twenty-four out of 29 patients had good to excellent outcome. Conclusion. Robotic assisted bicompartmental arthroplasty using broad indications and only excluding patients with severe deformity and those that have less than 4 mm of joint space in the surviving compartment demonstrated 83% good to excellent results.

Fracture of the Tibial Baseplate in Bicompartmental Knee Arthroplasty

Introduction. Bicompartmental knee arthroplasty (BKA) addresses combined medial and patellofemoral compartment osteoarthritis, which is relatively common, and has been proposed as a bridge between unicompartmental and total knee arthroplasty (TKA). Case Presentation. We present the case report of a young active man treated with BKA after unsuccessful conservative therapy. Four years later, loosening with fracture of the tibial baseplate was identified and the patient was revised to TKA. Discussion. Although our case is only the second fractured tibial baseplate to be reported, we believe that the modular titanium design, with two fixation pegs, is too thin to withstand daily cyclic loading powers. Light daily routine use, rather than high-impact sports, is therefore advised. Failures may also be related to the implant being an early generation and known to be technically complex, with too few implant sizes. We currently use TKA for the treatment of medial and patellofemoral compartment osteoarthritis.

Robotic-assisted unicompartmental knee arthroplasty.

In recent years, development of computer graphics and haptic feedback technology enabled the use of virtual reality. Virtual reality provides the opportunity to combine 3D visual imagery with interactivity, visual, and tactile realism. Robotic-assisted orthopedic surgery is defined as the use of computers and robotic technology to assist the orthopedist in providing musculoskeletal care, in which machine has the capability of precision and accuracy. Robotic-assisted orthopedic surgery is used in simulating diagnosis, preoperative and intraoperative planning, and actual surgery. One of the main areas for computer-assisted surgical applications is unicompartmental or bicompartmental knee arthroplasty, in which the clinical efficacy is improved by providing enhanced component positioning with dynamic ligament balancing.

Kinematics of monoblock bicompartmental knee arthroplasty during weight-bearing activities.

There is an increased interest in treating arthritis of the medial and patellofemoral compartments without using a total knee arthroplasty. The purpose of this study was to measure kinematics in knees with a monoblock bicompartmental arthroplasty to see whether maintaining the cruciate ligaments and lateral compartment resulted in consistent kinematics more similar to healthy knees than those observed in replaced knees. The kinematics of ten knees with monoblock bicompartmental arthroplasty were observed using fluoroscopy during three weight-bearing activities. Model-image registration techniques were used to quantify the three-dimensional motions of the knee joints. During kneeling, lunging, and stair-step activities, the medial condyle remained relatively close to the centre of the tibial plateau, while the lateral condyle typically moved posteriorly with flexion. Knees generally exhibited motion patterns consistent with retained cruciate ligament function, but individual patterns varied significantly. Bicompartmental knee arthroplasty has the potential to retain more natural knee function. Improved tools for aligning the implants and increased implant sizing options may be required to achieve highly consistent results and realize the clinical benefit of a knee arthroplasty with intact cruciate ligaments. III.