Current Practice Trends in Knee Arthroplasty in India Among ISHKS Members: ISHKS Annual Meeting 2019.

Aim: To assess the current practice trends in knee arthroplasty in India among ISHKS members. Methods: Literature review on 12 areas of key interest in total knee arthroplasty was conducted. Twenty-eight questions pertaining to these key areas in total knee arthroplasty surgery were presented to the delegates for a physical voting with audience response system (ARS) at ISHKS meeting, Bangalore, 2019. The members who could not attend the meeting voted by an online monkey survey. All questions were given three responses: a. Agree, b. Disagree, and c. Abstain. Results: 310 delegates participated and 295 voted in the physical meeting and 110 voted online. Consensus was reached for 28 statements representing five domains on the best practices. Overall, 92% of statements reached unanimous or strong consensus. The statements that achieved strong majority (> 90%) were the factors on pre-operative skin preparations, administration of antibiotics 30 min prior skin incision, and current practices of bilateral TKR. Furthermore, there was strong consensus approval on the role of aspirin for prophylaxis of DVT, lack of benefit on use of drain, considerations for pre-emptive analgesia, and neuraxial anesthesia. Finally, there were disparate views and weak consensus on use of laminar airflow theaters and use of surgical space suits, length of antibiotic administration postoperatively, and linking of DVT with PE and death. Conclusion: This study gives the surgeon practice preferences in knee arthroplasty in India and assists in clinical decision-making for all healthcare professionals.

Comparison with Navigation of a Novel Three-Step Technique for Improving Accuracy of the Distal Femoral Resection during Conventional TKA: A Case-Control Study.

Correct placement of the femoral component in the coronal plane during primary total knee arthroplasty (TKA) is related to long-term survival. The aim of this radiographic study was to determine the accuracy of a novel three-step technique for improving the accuracy of the distal femoral cut during conventional technique and compare it with computer navigation during TKA. A total of 458 TKAs were retrospectively analyzed (178 conventional TKAs with the novel technique and 280 navigated TKAs) for postoperative femoral component coronal alignment and compared between the two groups. Mean femoral component coronal alignment was not significantly different (p = 0.314) between the two groups. There was no significant difference in the mean femoral component coronal alignment between varus and valgus knees. The number of outliers (90 ± 3 degrees) for femoral component coronal alignment was not significantly different between the two groups when assessed separately for varus and valgus deformities. The mean value of femoral component alignment using the conventional technique in knees with varus deformity <10 degrees was 88.8 degrees, in knees with varus deformity 10 to 20 degrees was 89.4 degrees, and in those with varus deformity >20 degrees was 90.2 degrees. Femoral component alignment in knees with varus <10 degrees was significantly different from those >20 degrees (p = 0.006); there was no significant difference between knees with varus <10 degrees and those with 10 to 20 degrees varus (p = 0.251), nor between 10 and 20 degrees varus knees and those with varus >20 degrees (p = 0.116). Using the novel three-step technique during conventional TKA to perform the distal femoral cut can help achieve femoral component coronal alignment comparable to the navigation technique.

Is it prime time for robotic-assisted TKAs? A systematic review of current studies.

Introduction: Less-than-optimum positioning of femoral and tibial components and improper soft tissue tension, with abnormal loads and reduced range of motion, may cause lower patient satisfaction rates. To reduce surgeon-related variables during TKA, technology-assisted TKA was introduced, including computer navigation and robotic-assisted surgery (RATKA). Although several studies show promising short- and long-term functional and radiological outcomes of RATKA, there are still concerns related to its absolute superiority over conventional TKA. Methods: This review aims to provide an updated insight into the most recent articles reporting on outcomes (functional, radiological, and complications) of RATKA through a systematic search of major databases. A comprehensive English literature search was performed by both authors through four databases (Embase, PubMed, Web of Science, and Scopus). The full text of the final eligible studies was evaluated for inclusion, resulting in 13 studies that are included in this review. Results: There were 2112 knees in the 13 studies, with a follow-up ranging from three months to 13 years; only three were randomized controlled trials (RCTs), and nine directly compared the results of RATKA with CTKA technique. Seven studies reported the operative time ranging from 76.8 to 156 min; six reported a longer operative time with RATKA. Length of hospital stay (LOS) was reported in six studies which ranged from 0.48 to 2.1 days; in four studies the LOS was shorter with RATKA. In seven of the nine studies comparing RATKA with CTKA, no difference in functional outcomes was found. Four out of six studies reported that the overall alignment had mechanical alignment within ±3° of neutral alignment in all RATKA patients with an HKA ranging from -0.3 to 1.8°. Only one study reported better radiological outcomes in the RATKA group. In six comparative studies, no difference was found in the incidence of complications between RATKA and CTKA. Conclusion: Although robotic-assisted total knee arthroplasty is a promising technology that provides better component alignment and superior early functional outcomes, the justification for its widespread adoption needs more robust evidence through well-designed and better long-term studies demonstrating superior, predictable, and durable clinical results compared to conventional total knee arthroplasty techniques.

Registration of Proximal Tibial Centre May Need to be Selectively Lateralized to Avoid Coronal Malalignment in Digitally-Assisted Knee Arthroplasty.

Purpose: Placement of prosthetic components and limb alignment can be adversely impacted by errors in identification of registration points in digitally assisted knee arthroplasty. The purpose of this study was to trigonometrically analyze the impact on the accuracy of coronal tibial component and limb alignment of discrepancy between the registered midpoint of the proximal bony tibia vis-à-vis the radiographic medio-lateral center of the lateralized final tibial implant in certain varus-deformed knees. Methods: We analyzed trigonometrically the angular difference θ in coronal alignment of tibial component and hip-knee-ankle angle resulting from lateral translation of the medio-lateral center of the final tibial implant, with respect to the initial registered midpoint of the proximal bony tibia. θ was calculated using the equation tan( θ ) = d/t, where d is the numerical distance between the registered point and the center of the final tibial tray position and t is the length of tibia distal to the resection. Results: One degree of varus malpositioning of the tibial component and the limb can occur for every 6.3 mm of lateral translation of the tibial implant with respect to the midpoint of the proximal bony tibia of average reported length (372 mm). The magnitude of this error is inversely proportional to tibial length and the patient's height. Conclusions: Coronal malalignment of the tibial component and the limb is directly proportional to the amount of lateral translation of the tibial tray with respect to the registered midpoint of the proximal bony tibia and inversely proportional to the patient's height. This may occur in cases with tibial extra-articular deformity, those undergoing reduction osteotomy, downsizing of the tray, or inadvertently during tibial preparation. The error can be avoided by initial registration of the tibial midpoint more laterally by templating, re-registering the new center of the resected tibial surface or osteotomy for extra-articular deformity.

Seven phenotypes of varus osteoarthritic knees can be identified in the coronal plane.

PURPOSE: Recommendations for resecting distal femur and proximal tibia in mechanical and anatomical alignment techniques are standardized. Kinematic alignment propagates individualizing resection planes. Whether significant variation exists, to warrant departure from standardized resection planes, has not been shown thus far in a large cohort of knees and with a wide range of varus deformity. The null hypothesis of this study was that there was no phenotypic variation in varus osteoarthritic knees. The aim of this paper was to determine whether distinct phenotypes could be identified, based on variations in coronal femoral and tibial morphology, which could aid in surgical planning and categorizing varus knees for future studies. METHODS: 2129 full-leg weightbearing radiographs were analyzed (1704 preoperative; 425 of contralateral arthritic knee). Measurements made were of HKA (hip-knee-ankle angle), VCA (valgus correction angle), mLDFA (lateral mechanical distal femoral angle), aLDFA (lateral anatomical distal femoral angle), MPTA (medial proximal tibial angle), MNSA (medial neck shaft angle), TAMA (angle between tibial mechanical and anatomical axes), and TPDR (percentage length of tibia proximal to extra-articular deformity). RESULTS: Seven distinct types were identified covering 2021 knees, reducible to 4 broad phenotypes: 11% were Type 1 'Neutral' knees showing values close to reported normal knees (mean VCA 5.5°, mLDFA 87°, aLDFA 81°). 38% were Type 2 'Intra-articular varus' with medial intra-articular bone loss (mean mLDFA 90.9°, MPTA 85.4°, VCA of 5.7°). 41% were Type 3 'Extra-articular varus' with extra-articular deformity (EAD). Type 3a had proximal tibial EAD; Type 3b had tibial diaphyseal EAD; Type 3c had femoral EAD (mean VCA 8.7°, HKA 166°), and severe medial bone loss (mean mLDFA 92°, MPTA 83°). 9% were Type 4 'Valgoid type' with features of valgus knees: Type 4a had medial femoral bowing (mean VCA 2.9°); Type 4b had significant distal femoral valgus (mean mLDFA 85.3°, aLDFA 78.6°). CONCLUSIONS: The null hypothesis that there was no phenotypic variation in varus osteoarthritic knees was rejected as considerable variation was found in coronal morphology of femur and tibia. Four broad phenotypic groups could be identified. Plane of the knee joint articular surface was quite variable. This has relevance to planning and performance of corrective osteotomies, unicompartmental and total knee arthroplasty. LEVEL OF EVIDENCE: III, retrospective cohort study.

Valgus arthritic knees can be classified into nine phenotypes.

PURPOSE: It is not shown whether anatomical variations exist in valgus arthritic limbs as to support individualized component and limb alignment. The null hypothesis was that there was no phenotypic variation of coronal femoro-tibial morphology in valgus knees. The aim was to determine whether distinct phenotypes of valgus knees could be identified to help surgical planning and classifying valgus knees for outcome studies. METHODS: Full-leg weight-bearing radiographs of 233 knees (182 preoperative; 51 of contralateral arthritic knee) were measured for HKA (hip-knee-ankle angle), VCA (valgus correction angle), mLDFA (lateral mechanical distal femoral angle), aLDFA (lateral anatomical distal femoral angle), MPTA (medial proximal tibial angle), MNSA (medial neck shaft angle), TAMA (angle between tibial mechanical and anatomical axes), and TBA (tibial bowing angle). RESULTS: Nine phenotypes were identified encompassing all 233 knees which could be clubbed into 4 broad types. Type 1 Neutral knees (12.5%) had almost normal values (mean VCA 5.3°, mLDFA 86.9°, aLDFA 81.1°). Type 2 'Intra-articular valgus' (22.7%) showed lateral compartment bone loss (mean mLDFA 83.9°; MPTA 90.2°). Type 3 'Extra-articular valgus' (35.2%) had extra-articular deformity: 3a showed valgus femoral bowing (mean VCA 2.7°); 3b valgus tibial bowing; 3c showed valgus tibial bowing with lateral femoral condyle wear (mean mLDFA 84.3°). Type 4 'Varus' type (29.6%) had features of varus knees: 4a had varus femoral bowing (VCA 8.3°); distal femur in 4b was akin to varus knees (mean mLDFA 89.3°) with lateral tibial bone loss (mean MPTA 91.2°). 4c had varus tibial bowing and deficient lateral femoral condyle (mLDFA 83.7°). 4d had varus tibial bowing and lateral tibial bone loss (mean MPTA 89.8°). CONCLUSIONS: The study identified four broad groups of valgus arthritic knees with nine phenotypes based on coronal plane variations in femoro-tibial morphology. This study may be of value in planning and performing corrective osteotomies, and planning the optimal position of femoral and tibial components in unicompartmental and total knee arthroplasty. The classification presented in this study may aid in categorizing valgus knees for outcome studies. LEVEL OF EVIDENCE: IV.

Arthritic knees with more than 10° valgus can have soft-tissue imbalance in flexion.

PURPOSE: Valgus knees have inferior outcomes compared to varus knees. There is little data regarding soft-tissue balance in flexion which may influence outcome in valgus knees undergoing TKA. The purpose of this study was to evaluate whether there is imbalance between medial and lateral flexion gaps in valgus deformity. A secondary aim was to compare soft-tissue balance in knees with valgus deformity less than 10° with those exceeding 10°. The null hypothesis was that there was no soft-tissue imbalance in 90° of flexion irrespective of magnitude of deformity. METHODS: 64 valgus knees (52 female and 12 male) with deformity from 0.5 to 27.5° (mean 188.77, SD 6.21) were studied in 54 patients (mean age 67.81 y, SD 8.69) undergoing navigated TKA. Medial and lateral gaps in extension and at 90° of flexion were compared (using Independent-samples t test) between knees with valgus < 10° with those > 10° using a validated dynamic method after resection of cruciates, menisci and osteophytes, and then after final trialling. RESULTS: Mean initial medial-lateral (ML) gap difference in extension was 2.63 mm (SD 2.63) and 2.09 mm (SD 3.78) in flexion, being tighter laterally. Initial ML gap differences in extension and flexion correlated with valgus deformity (R = - 0.514; p = 0.00001; R = - 0.325; p = 0.01, respectively). Initial ML gap differences in extension correlated with those in flexion (R = 0.42; p = 0.0005). Mean ML flexion and extension gap differences were 1.30 mm (SD 3.67) and 1.26 mm (SD 1.92) in knees with < 10° valgus, and 3.17 mm (SD 3.71) and 4.29 mm (SD 2.45) in those > 10° valgus; p values were 0.026 and < 0.001 respectively. CONCLUSION: The lateral flexion gap in valgus knees may be narrower than the medial flexion gap, especially in knees with > 10° deformity. This contrasts with native and varus knees, in which it exceeds the medial gap. This novel study indicates the need to identify valgus knees with lateral flexion gap tightness by distracting the posterior femoral condyles from the proximal tibia by dynamic stressing of the soft-tissues after resection of cruciates, menisci, and osteophytes, with the knee flexed to 90°. These findings, highlighting the need for restoring flexion gap balance, may improve the inferior outcomes in valgus knees. LEVEL OF EVIDENCE: IV.

A Protocol to Systematic Radiographic Assessment of Primary Total Knee Arthroplasty.

Although total knee arthroplasty (TKA) is considered one of the most successful procedures, however, a subset of patients are unsatisfied with the results, even with the introduction of new technologies and implant designs. Radiological assessment of TKA is still considered the most prevalent imaging modality for evaluating the knee joint pre-and postoperatively. Assessment of various angles and indices which could be measured in different radiographic views of the knee provides valuable information about the alignment of the entire limb and the individual prosthetic components, more so in the light of recent nuanced concepts of technique, alignment, and balance. This review article aims to present a comprehensive yet systematic approach to the most useful radiographic parameters for assessing the knee preoperatively and post-TKA by explaining the tools and techniques used for measuring various angles, indices and ratios in the coronal, sagittal and axial planes for diagnosis, preoperative planning, postoperative assessment, and routine follow-up. The protocol we followed in this review entailed first reporting the possible applications and software which could help in measuring these variables, then we mentioned the required series of knee radiographs. For the desired variables, we divided the assessment according to each plane, and in each, we reported the optimum position of the desired radiographic view followed by determining the axis and lines which will later form the desired angles to be measured; finally, we collected all the measurements in a table with the native knee values and the most accepted values after TKA.

Prediction of leg length change (LLC) after correcting varus and flexion deformity in patients undergoing TKA.

PURPOSE: Patients with varus and fixed flexion deformity (FFD) undergoing TKA may have a significant leg length change (LLC) after surgery. We aimed to determine the correlation between changes in HKA or FFD and leg length in patients undergoing TKA, the combined effect of coronal and sagittal plane deformity correction on LLC, and the possibility of estimating LLC mathematically. MATERIALS AND METHODS: This was a prospective radiographic evaluation of 242 knees, which had undergone primary unilateral TKA for advanced OA with varus and FFD. Full-length standing calibrated anteroposterior radiographs were used to measure the hip-knee-ankle axis (HKA) and functional leg length after adjusting for magnification. Clinical evaluation of FFD was done using a handheld goniometer. RESULTS: 224 knees (92.6%) showed increased limb length after TKA averaging 10.7 mm (SD 9.5 mm, P = .000). There was a significant correlation between the change in HKA and FFD from preoperatively to postoperatively with the amount of LLC (ρ 0.326 and 0.346, respectively, P = .000). FFD improvement from preoperatively to postoperatively was 8.1° to 1° (P = .000), respectively. A linear relationship was established between LLC and changes in HKA and FFD, where 10° improvement in HKA would result in an LLC of nearly 4 mm, and 10° improvement in FFD would result in a LLC of nearly 8 mm. CONCLUSION: LLC may be substantial after correcting varus and FFD with unilateral TKA, it correlates with the change in HKA and FFD and can be mathematically estimated. CLINICAL TRIALS . GOV IDENTIFIER: NCT03502382.

Can isolated removal of osteophytes achieve correction of varus deformity and gap-balance in computer-assisted total knee arthroplasty?

AIMS: The aims of this study were to determine the effect of osteophyte excision on deformity correction and soft tissue gap balance in varus knees undergoing computer-assisted total knee arthroplasty (TKA). METHODS: A total of 492 consecutive, cemented, cruciate-substituting TKAs performed for varus osteoarthritis were studied. After exposure and excision of both cruciates and menisci, it was noted from operative records the corrective interventions performed in each case. Knees in which no releases after the initial exposure, those which had only osteophyte excision, and those in which further interventions were performed were identified. From recorded navigation data, coronal and sagittal limb alignment, knee flexion range, and medial and lateral gap distances in maximum knee extension and 90° knee flexion with maximal varus and valgus stresses, were established, initially after exposure and excision of both cruciate ligaments, and then also at trialling. Knees were defined as 'aligned' if the hip-knee-ankle axis was between 177° and 180°, (0° to 3° varus) and 'balanced' if medial and lateral gaps in extension and at 90° flexion were within 2 mm of each other. RESULTS: Of 50 knees (10%) with no soft tissue releases (other than cruciate ligaments), 90% were aligned, 81% were balanced, and 73% were aligned and balanced. In 288 knees (59%) only osteophyte excision was performed by subperiosteally releasing the deep medial collateral ligament. Of these, 98% were aligned, 80% were balanced, and 79% were aligned and balanced. In 154 knees (31%), additional procedures were performed (reduction osteotomy, posterior capsular release, and semimembranosus release). Of these, 89% were aligned, 68% were balanced, and 66% were aligned and balanced. The superficial medial collateral ligament was not released in any case. CONCLUSION: Two-thirds of all knees could be aligned and balanced with release of the cruciate ligaments alone and excision of osteophytes. Excision of osteophytes can be a useful step towards achieving deformity correction and gap balance without having to resort to soft tissue release in varus knees while maintaining classical coronal and sagittal alignment of components. Cite this article: Bone Joint J 2020;102-B(6 Supple A):49-58.

Comparison of Functional Outcomes of Computer-Assisted vs Conventional Total Knee Arthroplasty: A Systematic Review and Meta-Analysis of High-Quality, Prospective Studies.

BACKGROUND: Computer-assisted navigation system (CAS) in total knee arthroplasty (TKA) has been shown to improve mechanical alignment and prosthesis positioning as compared to conventional TKA. However, the evidence with regard to whether CAS-TKA has better patient function over conventional TKA is not clear. This systematic review and meta-analysis compares functional outcomes of CAS vs conventional TKA at longer follow-up periods. METHODS: This study was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, Embase, gray literature, and clinicaltrials.gov were searched up to April 30, 2018. All prospective original studies (only level 1 and 2) that compared functional outcomes of CAS-TKA vs conventional TKA, with minimum 2-year follow-up, were included. The research question and eligibility criteria were established a priori. Pertinent data were extracted and random-effects model was used. RESULTS: A total of 18 studies with 3060 knees were included; of which 1538 underwent TKA with CAS and 1522 underwent conventional TKA. Studies were grouped based on the follow-up reported into: (1) ≥2 years to <5 years; (2) ≥5 years to <8 years; (3) >8 years. Pooled mean Western Ontario and McMaster Universities Osteoarthritis Index scores (P < .001) and Knee Society Score-function score (P = .03) were better in the CAS-TKA group in the 5- to 8-year follow-up. For the remaining follow-ups, there was no difference between the 2 groups. CONCLUSION: The meta-analysis concluded that there is limited evidence that CAS-TKA improves functional outcomes at 5- to 8-year follow-up as measured by Western Ontario and McMaster Universities Osteoarthritis Index and Knee Society Score-function scores. More prospective studies with larger sample size and longer-term follow-up are required to support the trend toward better functional outcomes with CAS.

The Effect of Sagittal Knee Deformity on Preoperative Measurement of Coronal Mechanical Alignment during Total Knee Arthroplasty.

PURPOSE: The purpose of this prospective study was to determine correlation between coronal mechanical alignment measured on preoperative standing full-length radiographs and navigation during total knee arthroplasty (TKA) in the presence of an associated sagittal deformity (hyperextension and flexion deformity). MATERIALS AND METHODS: Coronal mechanical alignment measured on preoperative, standing, full-length, hip-to-ankle anteroposterior radiographs was compared with intraoperative measurements recorded with computer navigation in 200 primary navigated TKAs. RESULTS: The mean difference in mechanical alignment between the two techniques was significantly greater (p=0.001) in patients with an associated flexion deformity >10° when compared to knees with associated flexion deformity ≤10°; 48% of knees with a flexion deformity >10° had a difference of ≥3° between the full-length radiograph and navigation alignment measurements. There was a strong correlation between the radiographic and navigation measurement techniques. CONCLUSIONS: The mean difference in coronal mechanical alignment between the two techniques was significantly higher in patients with an associated flexion deformity >10°. Hence, surgeons should take caution when relying on preoperative full-length radiographs for determining coronal mechanical alignment in patients with an associated flexion deformity >10° where using navigation may be more reliable.

Windswept deformities - An indication to individualise valgus correction angle during total knee arthroplasty.

PURPOSE: We aimed to determine variation in femoral valgus correction angle (VCA) between the two limbs in a patient with windswept deformity undergoing total knee arthroplasty (TKA). METHODS: Femoral VCA was measured on full-length, hip-to-ankle, standing radiographs and was compared between the varus and the valgus limbs in 66 patients with windswept deformities. RESULTS: The mean VCA in varus knees was significantly higher compared to mean VCA in valgus knees (p = 0.002). CONCLUSION: Significant difference in VCA is present between the varus and the valgus limbs in most patients with windswept deformity undergoing TKA.

Mobile-bearing medial unicompartmental knee arthroplasty restores limb alignment comparable to that of the unaffected contralateral limb.

Background and purpose - Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. We investigated whether restoration of natural soft tissue tension would result in a lower limb alignment similar to that of the contralateral unaffected lower limb after mobile-bearing medial UKA. Patients and methods - In this retrospective study, hip-knee-ankle (HKA) angle, position of the weight-bearing axis (WBA), and knee joint line obliquity (KJLO) after mobile-bearing medial UKA was compared with that of the unaffected (clinically and radiologically) contralateral lower limb in 123 patients. Results - Postoperatively, HKA angle was restored to within ±3° of the contralateral lower limb in 87% of the patients and the WBA passed within ±1 Kennedy and White's tibial zone of the unaffected contralateral lower limb in 95% of the patients. The mean KJLO in the operated limbs was not significantly different from that in the unaffected lower limbs (p = 0.07) and the KJLO in the operated limb was restored to within ±3° of that in the contralateral lower limb in 96% of the patients. Interpretation - Lower limb alignment and knee joint line obliquity after mobile-bearing medial UKA were comparable to that of the unaffected contralateral limb in most patients. Comparison with the contralateral unaffected lower limb is a reliable method for evaluation and validation of limb mechanical alignment after mobile-bearing medial UKA.

Efficacy of a novel iPod-based navigation system compared to traditional navigation system in total knee arthroplasty.

BACKGROUND: This prospective study aimed to verify the efficacy of a novel, hand-held, iPod-based navigation system in comparison to traditional navigation system for total knee arthroplasty (TKA). METHODS: Limb alignment, tibial and distal femoral bone cut thickness and plane were recorded intraoperatively using both iPod-based and traditional navigation system in 36 knees undergoing primary TKAs. RESULTS: Intraoperatively, the iPod-based navigation system showed good to excellent correlation and reliability for tibial and distal femoral bone cut thickness, plane of the femoral cut and limb alignment when compared to the traditional navigation system. CONCLUSIONS: Despite its quick registration feature, the iPod-based system has an efficacy similar to traditional navigation system and is a positive step towards making navigation systems for TKA more compact, user-friendly, time and cost-effective.

Nanobiotechnology Perspectives on Prevention and Treatment of Ortho-paedic Implant Associated Infection.

Implants are an inevitable part of orthopaedic surgery. However, implant associated infection remains a major challenge for orthopaedic surgeons and researchers. This review focuses on current options available for prevention of implant associated infection, their drawbacks and future promising applications of nanotechnology-based approaches. Nanobiotechnology has shown remarkable progress in recent years especially in biomaterials, diagnostics, and drug delivery system. Although several applications of nanobiotechnology in orthopaedics have been described, few have elaborated their role in the prevention of implant related infection in orthopaedics. Novel "smart" drug delivery systems that release antibiotics locally in response to stimuli such as pH, temperature, enzymes or antigens; implant surface modification on a nanoscale to inhibit bacterial adhesion and propagation at the surgical site and biological approaches such as gene therapy to neutralize bacterial virulence and biomolecules to inhibit the quorum sensing adhesion of bacteria and disruption of biofilms can be used effectively to prevent orthopaedic implant related bacterial infection.

No effect of obesity on limb and component alignment after computer-assisted total knee arthroplasty.

PURPOSE: This retrospective study aimed to determine if computer navigation provides consistent accuracy for limb and component alignment during TKA irrespective of body mass index (BMI) by comparing limb and component alignment and the outlier rates in obese versus non-obese individuals undergoing computer-assisted TKA. METHODS: Six hundred and thirty-five computer assisted total knee arthroplasties (TKAs) performed in non-obese individuals (BMI<30 kg/m(2)) were compared with 520 computer-assisted TKAs in obese individuals (BMI ≥ 30 kg/m(2)) for postoperative limb and component alignment using full length standing hip-to-ankle radiographs. RESULTS: No significant difference in postoperative limb alignment (179.7° ± 1.7° vs 179.6° ± 1.8°), coronal femoral (90.2° ± 1.6° vs 89.8° ± 1.9°) and tibial component (90.2° ± 1.6° vs 90.3° ± 1.7°) alignment and outlier rates (6.2% vs 7.5%) was found between non-obese and obese individuals. Similarly, alignment and the outlier rates were similar when non-obese individuals and a subgroup of morbidly obese individuals (BMI >40 kg/m(2)) were compared. CONCLUSIONS: Computer navigation can achieve excellent limb and component alignment irrespective of a patient's BMI. Although obesity may not be an indication per se for using computer navigation during TKA, it will help achieve consistently accurate limb and component alignment in obese patients. LEVEL OF EVIDENCE: Level II.