Search

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.

Purpose: The purpose of this study was to analyze clinical outcomes in patients who underwent posterior cruciate ligament reconstruction (PCLR) with and without remnant preservation., Methods: A search of the literature was performed with the established medical databases Medline, Embase, and the Cochrane Register. Two authors screened the selected articles for title, abstract, and full text in accordance with predefined inclusion and exclusion criteria. The inclusion criteria were as follows: English-language articles on isolated posterior cruciate ligament injury; clinical trials with a clear description of surgical technique; outcome evaluation using a well-defined knee score, arthrometry, and posterior stress radiography; follow-up longer than 2 years; and a Coleman Methodology Score (CMS) of 65 points or greater. The methodologic quality of all articles was assessed by 2 authors according to the CMS., Results: Eleven studies were included, with a mean CMS of 78.9 points (SD, 5.37 points). There was no direct comparative study between remnant-preserving PCLR and standard PCLR. At final follow-up, the knees of 72% to 100% of patients who underwent remnant-preserving PCLR and 41% to 95% of patients who underwent standard PCLR were rated as normal or nearly normal on the International Knee Documentation Committee subjective knee assessment. Patients who underwent remnant-preserving PCLR showed an increase of 16.4 to 47 points in Lysholm scores, and patients who underwent standard PCLR showed an increase of 22 to 29 points. The ranges of mean postoperative side-to-side differences on KT-1000 (MEDmetric, San Diego, CA) testing were 0.7 to 2.8 mm in patients who underwent remnant-preserving PCLR and 1 to 3.5 mm in patients who underwent standard PCLR. The ranges of mean postoperative side-to-side differences on stress radiography were 2.2 to 5 mm in patients who underwent remnant-preserving PCLR and 4.7 to 6 mm in patients who underwent standard PCLR., Conclusions: All studies on PCLR with remnant preservation showed satisfactory outcomes despite using numerous surgical techniques, graft types, intervals from injury to surgery, and follow-up periods., Level of Evidence: Level IV, systematic review of Level II through IV studies., (Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this retrospective study was (1) to evaluate the radiographic features to differentiate arthroscopically confirmed complete and incomplete discoid lateral meniscus (DLM) (2) to determine the cutoff values for any parameter that was found to differentiate complete from incomplete DLM., Materials and Methods: We retrospectively analyzed plain knee radiographs of 130 arthroscopically proven DLM. Seventy-nine patients had complete DLM and 51 patients incomplete DLM. Knee radiographs from 52 patients with arthroscopically proven normal lateral meniscus acted as control group. Radiographic parameters measured included fibular height, lateral joint space, condylar cutoff sign, height of lateral tibial spine, obliquity of lateral tibial spine, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau., Results: Among radiographic parameters, high fibular head, widening of the lateral joint space and femoral condylar cutoff sign showed statistically significant (p<0.0001) differences between complete and incomplete DLM. At specific threshold points of fibular height<11 mm, lateral joint space>6 mm and condylar cutoff sign<0.80, the diagnosis of complete DLM revealed 87.3% sensitivity, 81.6% specificity and 78.4% positive predictive value (PPV) for the fibular height, 81.0% sensitivity, 86.6% specificity and 83.1% PPV for the lateral joint space, and 86.1% sensitivity, 83.5% specificity and 80% PPV for the condylar cutoff sign., Conclusions: Radiographic features of fibular height, lateral joint space and condylar cut off sign can be used for screening of a complete type of DLM. However, radiographs are not a reliable screening tool for an incomplete DLM., Level of Evidence: IV, Case Series., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Reduction osteotomy (removing the posteromedial tibial bony flare) is one step to aid in achieving deformity correction in varus arthritic knees during TKA. However, the amount of deformity correction achieved with reduction osteotomy during TKA is unclear., Questions/purposes: We therefore addressed the following questions: (1) What is the amount of deformity correction achieved with reduction osteotomy during TKA in varus knees? (2) What is the correlation of amount of deformity correction achieved to the amount of bone osteotomized and the degree of varus deformity?, Methods: We prospectively collected and analyzed intraoperative data on the degree of varus deformity before and after reduction osteotomy (using computer navigation) and the amount of reduction osteotomy performed (using a measuring scale) in 71 primary, computer-assisted TKAs., Results: For a mean reduction osteotomy of 7.5 ± 2 mm, a mean correction of 3.5° ± 1° was achieved; a mean osteotomy of 2 mm was required (confidence interval, 1.7-2.6 mm) for every 1° correction of varus deformity. Degree of varus correction achieved correlated positively with the amount of osteotomy performed, especially in knees with preoperative varus deformity of < 15° (r = 0.77, p < 0.001) and the preosteotomy residual varus deformity correlated positively with the amount of correction achieved (r = 0.81, p < 0.001)., Conclusions: Reduction osteotomy can achieve deformity correction in a predictable 2 mm for 1° in most varus arthritic knees during TKA. Further studies are required to ascertain its effectiveness as a soft tissue-sparing step when performed early on during TKA to achieve deformity correction.

Background: Extensive posteromedial release to correct severe varus deformity during TKA may result in mediolateral or flexion instability and may require a constrained implant. We describe a technique combining computer navigation and medial condylar osteotomy in severe varus deformity to achieve a primary goal of ligament balance during TKA., Description of Technique: The goal of this procedure was to achieve mediolateral gap balance in varus knees with rigid, recalcitrant medial contracture, with or without excessive lateral laxity, not amenable to extensive medial soft tissue releases. A sliding medial condylar osteotomy (SMCO) was performed under navigation guidance and the condylar block internally fixed using cancellous screws., Methods: We prospectively evaluated mediolateral laxity, Knee Society scores, and knee ROM after SMCO in 12 varus arthritic knees in 11 patients (five men, six women) undergoing TKA with a minimum followup of 2 years (mean, 2 years; range, 2-2.5 years)., Results: The degree of mediolateral knee laxity improved from Grade 2 (in four knees) and Grade 3 (in eight knees) preoperatively to Grade 1 (< 5 mm) in all knees at last followup. Mean Knee Society score improved from 30 (range, 10-54) to 92 (range, 86-100). Mean knee flexion improved from 106° (range, 90°-120°) to 112° (range, 100°-124°), and no knee had any extensor lag or residual flexion deformity (> 5°). Three knees had asymptomatic fibrous union at the osteotomy site., Conclusions: Computer-assisted SMCO in varus knees with recalcitrant medial contracture achieves improved mediolateral stability and knee function after TKA. Our technique uses navigation to accurately reposition the medial condylar block to equalize medial and lateral gaps, thereby ensuring a stable well-aligned knee without deploying constrained implants.

Purpose: The purpose of this cadaveric study was to study the effect of plane of osteotomy on incidence of lateral cortex fracture and to define a "safe zone" through which medial open-wedge high tibial osteotomy (HTO) could be performed with minimal risk of lateral cortex fracture., Methods: Medial open HTO was performed in nine fresh frozen human cadavers (18 knees) with each specimen randomly assigned to a "safe zone" osteotomy (group A, between the tip of the fibular head and the circumference line of the fibular head), or a lower level osteotomy (group B, distal to the circumference line of the fibular head)., Results: Six out of nine knees developed lateral cortex fracture in group B compared to none in group A (P = 0.009) when the osteotomy site was distracted to a maximum of 20 mm., Conclusion: Directing the plane of the osteotomy toward the "safe zone" significantly reduces the risk of lateral cortex fracture compared to an osteotomy, which is directed at a lower level. Confining the plane of a medial open HTO to within the "safe zone" can prevent lateral cortex fracture and subsequent loss of correction.

We prospectively studied variations in valgus correction angle (VCA) and the influence of preoperative limb deformity on VCA in 503 consecutive total knee arthroplasties done in 393 patients. The percentage of limbs that had VCA values less than 5° was 10.9%, and that with VCA values greater than 7° was 44.9%. The percentage of limbs with VCA greater than 7° was significantly more in varus knees, and that with VCA less than 5° was significantly more in valgus knees; preoperative deformity showed a significant correlation with VCA. Choosing a fixed-routine VCA of 5° to 7° may cause an unacceptable planning error that may be minimized by individualizing VCA or using computer navigation., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: Computer navigation has improved accuracy and reduced the percentage of alignment outliers in TKA. However, the characteristics of outliers and the risk factors for limb malalignment after TKA are still unclear., Questions/purposes: We therefore addressed the following questions: (1) What is the incidence and characteristics of outliers for postoperative limb mechanical axis (hip-knee-ankle [HKA] angle outside the conventional 180° ± 3° range) and component alignment in TKA? And (2) what are the preoperative clinical or radiographic risk factors for limb mechanical axis malalignment in TKA?, Methods: We retrospectively reviewed the clinical and radiographic records of 1500 computer-assisted TKAs to identify outliers for postoperative HKA axis and component alignment and determined risk factors for malalignment. Full-length hip-to-ankle and knee radiographs were used to measure preoperative HKA angle, femoral coronal bowing, joint divergence angle, tibial subluxation, and tibial bone loss and postoperative HKA angle and femoral and tibial component angle., Results: The incidence of outliers for postoperative limb mechanical axis, femoral component alignment, and tibial component alignment was 7% (112 of 1500 TKAs), 7%, and 8%, respectively, with 70% of limbs placed in excessive varus and 30% in excessive valgus. Preoperative varus deformity of more than 20° and femoral bowing of more than 5° were associated with increased risk of placing the limb mechanical axis outside the acceptable ± 3° range after computer-assisted TKA., Conclusions: The presence of preoperative radiographic risk factors should alert the surgeon to increased chance of malalignment and every measure should be undertaken in such at-risk knees to ensure proper limb and component alignment and soft tissue balance.

Purpose: This prospective study aimed to evaluate radiographically, change in joint line and femoral condylar offset with the optimized gap balancing technique in computer-assisted, primary, cruciate-substituting total knee arthroplasties (TKAs)., Methods: One hundred and twenty-nine consecutive computer-assisted TKAs were evaluated radiographically using pre- and postoperative full-length standing hip-to-ankle, antero-posterior and lateral radiographs to assess change in knee deformity, joint line height and posterior condylar offset., Results: In 49% of knees, there was a net decrease (mean 2.2mm, range 0.2-8.4mm) in joint line height postoperatively whereas 46.5% of knees had a net increase in joint line height (mean 2.5mm, range 0.2-11.2mm). In 93% of the knees, joint line was restored to within ± 5 mm of preoperative values. In 53% of knees, there was a net increase (mean 2.9 mm, range 0.2-12 mm) in posterior offset postoperatively whereas 40% of knees had a net decrease in posterior offset (mean 4.2mm, range 0.6-20mm). In 82% of knees, the posterior offset was restored within ± 5 mm of preoperative values., Conclusions: Based on radiographic evaluation in extension and at 30° flexion, the current study clearly demonstrates that joint line and posterior femoral condylar offset can be restored in the majority of computer-assisted, cruciate-substituting TKAs to within 5mm of their preoperative value. The optimized gap balancing feature of the computer software allows the surgeon to simulate the effect of simultaneously adjusting femoral component size, position and distal femoral resection level on joint line and posterior femoral offset., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: The weightbearing axis of the limb goes from the pelvis to the ground and includes the hindfoot. However, the influence of hindfoot alignment on mechanical axis and overall limb alignment after TKA is unclear., Questions/purposes: We therefore addressed the following questions: (1) Does hindfoot alignment change after TKA for knee osteoarthritis? (2) What factors influence hindfoot alignment after TKA? (3) Does deviation of the mechanical axis from the center of the knee vary when the hindfoot is considered (ground mechanical axis) as compared with when it is not (conventional mechanical axis) after TKA?, Patients and Methods: We prospectively reviewed the radiographs of 125 patients who underwent 165 TKAs. We evaluated the preoperative and postoperative hip-knee-ankle (HKA) angle, conventional mechanical axis deviation, ground mechanical axis (mechanical axis which included the hindfoot) deviation, and tibiocalcaneal angle., Results: The preoperative hindfoot valgus alignment decreased after TKA. Preoperative hindfoot alignment was the only factor that influenced hindfoot alignment after TKA. The conventional mechanical axis showed less deviation from the center of the knee when compared with ground mechanical axis which showed lateral deviation after TKA. Despite limb alignment being restored to within 3° of neutral of the conventional mechanical axis after TKA, 29% of limbs had a postoperative ground mechanical axis deviation of 10 mm or greater., Conclusions: Accurate restoration of limb alignment after TKA may be associated with persistent hindfoot valgus alignment with the ground mechanical axis passing lateral to the center of the knee. This could have implications on long-term survival of the implant owing to possible excessive loading laterally and needs further investigation.

Extensive release of posterolateral structures may be required to correct rigid and severe valgus deformities during total knee arthroplasty. Current techniques are technically difficult, may not accurately restore soft tissue balance, and are associated with postoperative complications. Computer navigation while performing lateral femoral epicondylar osteotomy allows precise, controlled, quantitative lengthening of lateral structures and restoration of optimum soft tissue balance and alignment., (2010 Elsevier Inc. All rights reserved.)

Forty extra-articular deformities (22 femoral and 18 tibial) in 34 patients (mean age, 63.1 years) were studied. Mean coronal extra-articular deformity was 9.3 degrees ; mean preoperative limb alignment was 166.7 degrees . Three limbs underwent simultaneous corrective osteotomy; the rest were treated with intra-articular correction during computer-assisted total knee arthroplasty (TKA). Mean postoperative limb alignment was 179.1 degrees . At a mean follow-up of 26.4 months, the Knee Society knee score improved from a mean preoperative score of 49.7 to 90.4 points postoperatively; function score improved from 47.3 to 84.9 points. Computer-assisted TKA is a useful alternative to conventional TKA for knee arthritis with extra-articular deformity where accurate restoration of limb alignment may be challenging because of the presence of a deformed tibia or femur or in the presence of hardware.

Purpose: Our purpose was to evaluate the result of radial tears at the root of the posterior horn of the medial meniscus (PHMM) in terms of tibiofemoral contact mechanics and the effectiveness of pullout sutures for such tears., Methods: Eleven mature pig knees each underwent 15 different testing conditions with an intact, simulated (incised) radial tear at the root of the PHMM and placement of pullout sutures in the radial tears of the medial meniscus at 5 different angles of flexion (0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees ) under a 1,500-N axial load. A K-Scan pressure sensor (Tekscan, Boston, MA) was used to measure medial tibiofemoral contact area and peak tibiofemoral contact pressure. Data were analyzed to assess the difference in medial contact area and tibiofemoral peak contact pressure among the 3 meniscal conditions at various degrees of knee flexion., Results: The mean contact area was significantly lower, and the peak tibiofemoral contact pressure was significantly high in knees with simulated radial tears at all angles of knee flexion compared with knees with intact menisci (P < .0001). The peak tibiofemoral contact pressure after the pullout suture technique was significantly high at 0 degrees and 15 degrees of flexion (P < .0001) compared with intact knee specimens. Failure of sutures occurred in 45% of the specimens at 0 degrees of flexion., Conclusions: Radial tears at the root of the PHMM in a porcine model significantly increased medial tibiofemoral contact pressure and decreased contact area. Although repair of tears of the PHMM with the pullout suture technique aids in significantly reducing tibiofemoral peak contact pressure between 30 degrees and 90 degrees , it remains significantly high at 0 degrees and 15 degrees of flexion., Clinical Relevance: Pullout sutures for radial tears at the root of the PHMM may lead to an increase in peak medial tibiofemoral contact pressure and may be prone to mechanical failure, especially during the stance (loading) phase of gait (mean, 15 degrees of flexion).

Localized pigmented villonodular synovitis involving the posterior intra-articular structures of the knee joint is rare. We report a case of localized pigmented villonodular synovitis arising from the posterior capsule of the knee joint in a patient who presented with a history of repeated joint effusions and loss of terminal knee flexion. After successful, complete removal of the mass through the posteromedial portal, the patient was asymptomatic, with no evidence of recurrence during the 26-month follow-up period.

Alcohol-induced osteonecrosis of femoral head is common but multifocal osteonecrosis secondary to alcohol is very rare. The authors report one case of multifocal alcohol-induced osteonecrosis involving both hips and both knees and its subsequent progression and management over a period of 14 years. There was bilateral involvement of hips in pre-collapse stage for which a core decompression was done. The left hip responded well and at 14-year follow-up was asymptomatic with full range of motion. The core decompression surgery failed in the right hip within 1 year and subsequently hybrid total hip replacement arthroplasty was done with good functional results at 13 years follow-up. The diagnosis of knee osteonecrosis was most probably missed initially and was subsequently diagnosed 6 months back due to symptoms of pain and radiographic findings for which a core decompression was done with good early results. The results of treatment of hip was excellent in our patient and despite the rarity, a high degree of suspicion and regular screening is necessary to detect involvement of other areas like the knee in alcohol-induced osteonecrosis.

Synovial cysts are well-defined fluid filled cysts that can extend for a variable distance outside the joint space. These cysts can sometimes grow to a large size making its treatment challenging especially when associated with intra-articular pathologies. We describe a case of giant synovial cyst arising from the left knee and extending to the medial proximal calf in a 77-year old female who presented with knee joint pain, episodes of locking and calf mass occurring within 2 months of onset. Imaging studies also showed associated medial and lateral meniscal tears with medial compartment and patellofemoral osteoarthritis. The cyst was treated by disrupting the valvular mechanism using a standard posteromedial portal and complete excision of the cyst wall via a posteromedial cystic portal. The meniscal lesions were dealt with through the standard anterior portals. At 25-month follow up there were no signs of recurrence of the cyst clinically or with MRI. The cystic portal technique is effective in treating a giant synovial cyst of the knee even in the presence of meniscal tears and high grade chondral lesions.

We assessed the effect of foot deformity on the loading axis of lower limbs in 33 patients with genu varum (25 bilateral and eigth unilateral) caused by varying etiologies including achondroplasia, cerebral palsy, prior trauma, rickets, metaphyseal chondrodysplasia and primary osteoarthritis using single leg stance and both leg stance radiographs. Deviation at the knee from the hip ankle line (conventional) and hip foot line (centre of hip to centre of heel) was calculated. A comparison was made between single leg stance and two leg stance for tibiocalcaneal angle, mechanical axis angle, knee and ankle joint line convergence angle, conventional mechanical axis deviation (MADC) and ground mechanical axis deviation (MADG). In addition comparisons were also made among three groups formed depending on the tibiocalcaneal angle and MADC-MADG difference for all the above measurements. Mechanical axis deviation (calculated using the two methods) varied with the talocalcaneal angle and single leg stance. Patients with a fixed subtalar varus and with severe genu varum, where the normal compensatory subtalar eversion could not compensate showed that conventional mechanical axis deviation was significantly higher by 3.4+/-2.4 mm and ground mechanical axis deviation degrees was significantly higher by 3.8+/-3.2 mm in single leg stance when compared to two leg stance (p<.0001). Foot deformity should be included during preoperative evaluation and planning for knee deformity correction.

Background: Distraction-resisting forces that are generated during distraction osteogenesis can be responsible for complications, including a lag effect on fibular distraction leading to a tibiofibular distraction difference, tibial axial deviation, and distraction at the proximal and distal tibiofibular joints. We investigated the nature of distraction-resisting forces by studying their correlation with these parameters.Methods: One hundred and eleven tibial lengthening procedures in sixty-three patients were chosen. Seventy-six segments underwent lengthening with an Ilizarov ring fixator, and thirty-five segments had lengthening over an intramedullary nail. Serial radiographs were evaluated with regard to the amounts of tibiofibular distraction difference, proximal tibiofibular joint distraction, distal tibiofibular joint distraction, tibial axial deviation, and heel malalignment. Clinically, laxity at the knee was evaluated and fibular head instability was assessed. Variations in all of these parameters were evaluated with respect to tibiofibular joint fixation, etiology, skeletal maturity, lengthening over an intramedullary nail, and amount of lengthening.Results: The mean tibiofibular distraction difference was 19.1 +/- 10.6 mm (range, 2 to 51 mm), the mean proximal tibiofibular joint distraction was 10.1 +/- 6.8 mm (range, 0 to 33 mm), and the mean tibial valgus angulation was 8.7 degrees +/- 4.4 degrees . At the time of the latest follow-up, twenty-eight segments (25%) had lateral knee joint laxity at 30 degrees of knee flexion and eight segments (7%) had fibular head subluxation at 90 degrees of knee flexion. Twenty-four (86%) of the twenty-eight cases of knee laxity were observed in skeletally immature patients. The tibiofibular distraction difference, proximal tibiofibular joint distraction, and tibial valgus angulation were significantly greater in the group without fixation of the proximal tibiofibular joint. A significant decrease in the tibial valgus angulation and knee laxity was found in patients with lengthening over an intramedullary nail. In the intramedullary nail group, after fixation of the proximal tibiofibular joint, the tibiofibular distraction difference and the proximal tibiofibular joint distraction decreased; however, the proportion of cases with clinically important tibial valgus angulation (>10 degrees ) increased significantly.Conclusions: Fixing both tibiofibular joints with a single Ilizarov wire decreases proximal tibiofibular joint distraction; however, more secure fixation would help to decrease the prevalence of delayed knee laxity. When tibial lengthening is performed over an intramedullary nail, avoiding proximal tibiofibular joint fixation will limit tibial valgus angulation. Limiting lengthening to <25% will decrease the proportion of cases with knee laxity, and limiting lengthening to <50% will significantly limit tibial valgus angulation. [ABSTRACT FROM AUTHOR]