Tibial tubercle osteotomy for patellofemoral malalignment and chondral disease provided good outcomes: A systematic review.

IMPORTANCE: Tibial tubercle osteotomy (TTO) is indicated to treat patellofemoral (PF) malalignment and chondral disease refractory to conservative treatment. However, there are no systematic reviews describing TTO outcomes in chondral damages without instability. AIM: The aims of this study were to (1) assess the quality of the published studies, (2) identify indication for TTO to treat PFP with chondral disease without instability, (3) evaluate the most common TTO techniques, (4) evaluate the clinical outcomes, and (5) evaluate TTO's complication and failure rates. EVIDENCE REVIEW: In December 2020, a literature search was performed applying the following criteria: (1) peer-reviewed Level 1-4 studies; (2) English language; (3) human subjects with clinical and/or radiological outcomes; (4) TTO alone or associated with minor cartilage procedure (only drilling, no instability); (5) minimum follow-up 12 months, minimum 10 patients; and (6) no more than 20% of drop-out rate. Data from studies were collected and described with weighted averages and standard deviations. FINDINGS: A total of 18 Level 4 studies were included. The average Coleman Methodology Score was 61.5 points (range 48-81). A total of 851 patients (892 knees) were included, with 64.8% of female patients. The weighted average follow-up was 49.1 months (range 12-128.5). Indication for TTOs was poorly described. The main technique used was anteromedialisation (60.4%). In 27.7% of the cases, TTO was associated with lateral release. Different scoring systems were used to evaluate outcomes, with significant improvements. The average rate of good/excellent results was 78.7% (range 57%-100%). Fifteen studies described the complication rate (9.9%), whereas only four reported the failure rate (6.2%). CONCLUSION AND RELEVANCE: TTOs performed to treat PF malalignment associated with chondral disease without instability provided good clinical outcomes, with acceptable complication/failure rates. However, high-level studies are necessary because of studies' heterogeneity regarding patellofemoral malalignment and chondral disease treatment. STUDY DESIGN AND LEVEL OF EVIDENCE: Systematic review. LEVEL OF THE STUDY: Level IV, systematic review of Level IV studies.

Incidence and pattern of periprosthetic hip fractures around the stem in different stem geometry.

BACKGROUND: The number of total hip arthroplasties (THA) is expected to increase worldwide; thus, complications are likely to increase at the same ratio. In this scenario, periprosthetic femoral fractures (PFFs) are an increasing concern. Identifying the predisposing factors is important in order to prevent as much as possible the risk of PFF in the future. PATIENTS AND METHODS: The purpose of this study was to correlate the risk of periprosthetic femoral fractures to the most common patients' comorbidities and stem geometry. We reviewed all THA for non-oncologic indications between 2004 and 2014 with a mean follow-up of six years (range, 2-12). Three thousand two hundred forty-eight patients (3593 implants) were enrolled in the study, and 45 PFF were registered during this time period. Two thousand five hundred seventy-seven implants (71%) were straight stems, and 1015 (28.3%) were anatomic stems. All X-rays were then analyzed and classified according to the modified Vancouver classification. RESULTS: Periprosthetic femoral fractures incidence was associated with anatomic stem geometry (p < 0.001, OR = 2.2), BMI (p < 0.001), and diabetes (p < 0.001, OR = 5.18). PFFs were not significantly associated with age, gender, and all the other variables. Fracture pattern was different between straight and anatomic stems. Clamshell fractures were more likely to occur in anatomic stems compared to straight stems (p < 0.005). CONCLUSIONS: Periprosthetic femoral fractures are highly associated with obesity and osteoporosis. Anatomic stems reported a higher incidence of PPF than straight stems. The typical fracture type for anatomical stems is the clamshell pattern, while straight stems are more likely affected by type B fractures.

Modifiable and Nonmodifiable Predictive Factors Associated with the Outcomes of Total Knee Arthroplasty.

Total knee arthroplasty (TKA) is a valuable treatment option for advanced osteoarthritis in patients unresponsive to conservative treatments. Despite overall satisfactory results, the rate of unsatisfied patients after TKA remains high, ranging from 5 to 40%. Different modifiable and nonmodifiable prognostic factors associated with TKA outcomes have been described. The correction, whenever possible, of modifiable factors is fundamental in preoperative patients' optimization protocols. Nonmodifiable factors can help in predicting the outcomes and creating the right expectations in the patients undergoing TKA. The goal of this review is to summarize the modifiable and nonmodifiable prognostic factors associated with TKA outcomes.

Hip Spacers in Two-Stage Revision for Periprosthetic Joint Infection: A Review of Literature.

Infection after total hip arthroplasty (THA) is a devastating complication with significant consequences for patients. In literature, single and two-stage revision, irrigation and debridement, Girdlestone resection arthroplasty, and arthrodesis and amputation are reported as possible treatments. Recently, two-stage revision has become popular as the gold standard treatment for chronic hip joint infections after THA. In this review, we evaluate the current literature about microbiology of periprosthetic joint infections and the use of antibiotic-loaded cement spacers. We aim to give an overview about indications, clinical results, and mechanical complications for spacers implantation, evaluating also selection criteria, pharmacokinetic properties, and systemic safety of the most frequently used antibiotics.

Revision total knee arthroplasty (TKA): mid-term outcomes and bone loss/quality evaluation and treatment.

BACKGROUND: Revision total knee arthroplasty (rTKA) is a demanding procedure, with a high complication and failure rate and a high rate of bone losses and poor bone quality. Different classifications for bone losses have been proposed, but they do not consider bone quality, which may affect implant fixation. The aim of this study is to describe the outcomes of a consecutive series of rTKA. Furthermore, a modified bone loss classification will be proposed based also on bone quality. Finally, the association between radiolucent line (RLL) development and different risk factors will be evaluated. METHODS: All the patients who underwent rTKA between 2008 and 2016 in the same institution were included. rTKAs were performed by the same surgeon according to the three-step technique. Bone losses were classified according to the proposed classification, including bone quality evaluation. The Knee Scoring System (KSS), the Hospital for Special Surgery Knee Score (HSS), and the SF-12 were used for the clinical evaluation. Radiological evaluation was performed according to the Knee Society Roentgenographic Evaluation System. Different possible risk factors (i.e., gender, age, amount of bone losses) associated to RLL development were identified, and this association was evaluated using logistic regression. RESULTS: Fifty-one patients (53 knees) were included (60.8% female, average age 71.5 years). The average follow-up was 56.6 months (range 24-182). The most frequent cause of failure was aseptic loosening (41.5%). 18.9% of the cases demonstrated poor bone quality. Bone losses were treated according to the proposed algorithm. In all the cases, there was a significant improvement in all the scores (P < 0.05). The average post-operative range of motion was 110.5° (SD 10.7). At the radiological evaluation, all the implants resulted well aligned, with 15.1% of non-progressive RLL. There were 2 failures, with a cumulative survivorship of 92.1% at the last follow-up (SD 5.3%). At the logistic regression, none of the evaluated variables resulted associated to RLL development. CONCLUSION: rTKA is a demanding procedure, and adequate treatment of bone losses is mandatory to achieve good results. However, also bone quality should be taken into consideration when approaching bone losses, and the proposed classification may need surgeons after an adequate validation. LEVEL OF EVIDENCE: Level IV.

Lateral Opening Wedge Distal Femoral Osteotomy for Lateral Compartment Arthrosis/Overload.

Distal femoral osteotomy (DFO) is a valid option for the treatment of young and active patients with lateral compartment osteoarthritis/overload and valgus malalignment. DFOs can be performed with a closing wedge or opening wedge technique. Lateral opening wedge DFO is usually preferred for smaller corrections, whereas medial closing wedge for larger corrections and in patients with high risk of nonunion. This article describes the relevant aspects regarding lateral opening wedge DFO, including patient selection, preoperative planning, surgical technique, results, and complications.

Total knee arthroplasty in the varus knee: tips and tricks.

Varus knee deformity is very common, and it can be classified according to the severity and reducibility of the deformity. Pre-operative planning is mandatory to obtain a good result. Both clinical and radiological planning should be carefully performed, particularly focused on collateral ligament deficiency. In most of the cases, a postero-stabilized implant is necessary, but in the presence of a varus thrust, a midlevel constrained (MLC) implant may be necessary. Rarely, if a severe extra-articular deformity is present, a femoral osteotomy and a high constrain implant may be necessary. In most of the cases, a standard midline approach can be performed. Soft tissue balancing is crucial, avoiding excessive releases of the medial collateral ligament (MCL). In the presence of severe deformity, more aggressive procedure such as tibial reduction osteotomy or sliding medial epicondyle osteotomy can be performed. In literature, good outcomes are reported for total knee arthroplasty (TKA) in varus deformity. In this manuscript, the available literature on TKA in varus deformity is analyzed, and the preferred surgical techniques of the authors are described.

Medial Patellofemoral Ligament Reconstruction and Nonanatomic Stabilization Techniques in Skeletally Immature Patients.

Patellar instability is a common cause of knee disability in children and adolescent, with a high recurrence rate. When conservative treatment fails, surgical options should be considered. The femoral insertion of the medial patellofemoral ligament (MPFL) is in close proximity to the distal femoral growth plate and precautions should be taken to avoid injuries to the physis. Anatomical features of the MPFL complex, with focus on the relationship between femoral MPFL attachment and femoral physis, are discussed together with surgical tips to avoid injuries to the growth plates. The aim of this article is to review the recent literature regarding MPFL reconstruction and other stabilization techniques for patellofemoral instability in skeletally immature patients, focusing on the different surgical options available. These can be classified as anatomical versus nonanatomical, proximal versus distal realignments, or based on the graft used: free graft and pedicled graft (quadriceps, patellar tendon, hamstring, and adductor magnus).

Factors Affecting Subjective and Objective Outcomes and Return to Play in Anterior Cruciate Ligament Reconstruction: A Retrospective Cohort Study.

Purpose To analyze the prognostic factors influencing subjective and objective outcomes and return to play (RTP) after anterior cruciate ligament reconstruction (ACL-R). Methods Primary ACL-Rs using a transtibial technique performed between 2008 and 2012 were included. Data regarding patients, surgery, sports, and rehabilitation, including an on-field rehabilitation (OFR) and duration of the rehabilitation program, were collected. The International Knee Documentation Committee (IKDC) subjective and objective evaluation forms, and the Knee Injury and Osteoarthritis Outcome Score and Lysholm questionnaires were used for the assessment of subjective and objective outcomes. The Subjective Patient Outcome for Return to Sports and ACL-return to sport after injury (RSI) scores were used for RTP evaluation. Several potential predictors of outcome were tested with a univariate analysis. All the variables with p < 0.1 were retested in a logistic regression model to evaluate their association with the outcomes. Results In total, 176 cases were included with an average follow-up of 44.1 months. Of the patients, 92.2% were rated as normal or nearly normal at the IKDC evaluation. In addition, 90.1% of the patients returned to sport, with 57.6% returning to the same preinjury level. Objective outcomes were negatively influenced by late rehabilitation (odds ratio [OR] = 2.75). Performing an OFR phase during the rehabilitation was associated with better subjective outcomes (OR = 2.71). Length of rehabilitation strongly influenced the RTP rate (OR = 13.16). Conversely, higher ACL-RSI score was inversely related to RTP. Objective IKDC score was inversely related to the ACL-RSI (OR = 0.31), whereas subjective score was correlated with both the total ACL-RSI score (OR = 0.15) and the level of activity (OR = 0.20). Conclusion This study confirmed the role of rehabilitation on subjective and objective outcomes and on RTP. Particularly, the complete adherence to a rehabilitation program, including an OFR phase, resulted in better subjective outcomes and higher RTP rate. The relationship between psychological factors, measured through the ACL-RSI score, and RTP was confirmed. Level of Evidence Level III, observational study without a control group.

Large Osteochondral Allografts of the Knee: Surgical Technique and Indications.

Large osteochondral allograft (OCA) transplant has become a valid alternative to restore articular surface in challenging articular lesions in young and active patients, either in primary or in revision procedures. Several studies support the effectiveness and safety of OCA, but costs and graft availability limit their use. The indications are the treatment of symptomatic full-thickness cartilage lesions greater than 3 cm 2 , deep lesions with subchondral damage, or revision procedures when a previous treatment has failed. The goal of the transplant is to restore the articular surface with a biological implant, allow return to daily/sports activities, relieve symptoms, and delay knee arthroplasty. Grafts can be fresh, fresh-frozen, or cryopreserved; these different storage procedures significantly affect cell viability, immunogenicity, and duration of the storage. Dowel and shell technique are the two most commonly used procedures for OCA transplantation. While most cartilage lesions can be treated with the dowel technique, large and/or geometrically irregular lesions should be treated with the shell technique. OCA transplantation for the knee has demonstrated reliable mid- to long-term results in terms of graft survival and patient satisfaction. Best results are reported: in unipolar lesions, in patients younger than 30 years, in traumatic lesions and when the treatment is performed within 12 months from the onset of symptoms.

Medium-term follow-up of 149 mobile-bearing total knee arthroplasties and evaluation of prognostic factors influencing outcomes.

OBJECTIVE: To evaluate the medium-term outcomes of a posterior-stabilized mobile-bearing total knee arthroplasty (PS-MB-TKA) and the role of different prognostic factors. METHODS: Patients indicated for a primary cemented PS-MB-TKA between 2002 and 2010 were included and prospectively evaluated using the Knee Society Scoring System (KSS) and the Hospital for Special Surgery (HSS) knee scores. The Knee Society Roentgenographic Evaluation form was used for the radiological evaluation. Different variables were collected and divided into patient- and surgery-related. Logistic regression was used to analyze the correlation between these variables and implants outcomes and survivorship. RESULTS: In total, 149 cases were included (67.8% female, average age 70.4 years, SD ±9.4). The patella was resurfaced in 12.1% of the cases. All the implants were cemented. The average follow-up was 87.3 months (SD ±21.2). Postoperatively, there was a statistically significant improvement in all the scores. The cumulative survival was 96.2% (SD ±0.02%). At the regression analysis, female gender was associated to worse satisfaction KSS (OR = 0.26), functional KSS (OR = 0.22), and HSS (OR = 0.37) scores. Patellar resurfacing and subsequent contralateral procedures were associated to better functional KSS score (OR = 4.13, OR = 2.21), as well as varus preoperative alignment (OR = 2.12). On contrary, valgus preoperative alignment was associated to worse objective KSS score (OR = 0.23). No variables were correlated to failure or presence of radiolucent lines. CONCLUSION: Good medium-term outcomes were obtained using PS-MB-TKA, with a cumulative survivorship of 96.5%. Female gender and valgus preoperative alignment were associated to worse objective and subjective outcomes. Conversely, patellar replacement, subsequent contralateral TKA, and varus preoperative alignment were associated to better functional outcomes.

Bore Disruption: An Unusual Mechanical Failure of Two Hip Hemiarthroplasties.

We report a case of two hemiarthroplasties (HAs) that underwent an unexpected mechanical failure. Two patients affected by femoral fractures were treated with an HA. At 5 and 7 years after surgery, they showed a breakage of the HA at the head-stem junction. We analyzed macroscopically and microscopically (by a scanning electron microscopy) the surfaces of the broken prostheses. In both cases, a fracture was detected starting at the joining point between the femoral head and the slot that receives the taper cone of the stem (the so-called bore), with the typical macroscopic and microscopic pattern of a fatigue fracture. The fatigue fracture resulted from repeated cycles of torsional stresses throughout the years. In literature, we did not find any other report of such HA failure.

Two-Stage Treatment of a Large Pelvic Cystic Pseudotumor in a Metal-On-Metal Total Hip Arthroplasty.

The authors report a case of a huge cystic pseudotumor, surrounding a failed metal-on-metal total hip arthroplasty (THA). The cyst surrounded the hip anteriorly, occupied part of the anterior portion of the thigh, and extended to the anterolateral aspect of the abdomen. The case was treated by a two-stage procedure. The first stage consisted of a percutaneous drainage of the fluid content of the cyst (∼1,200 mL). This procedure reduced the risk of tearing the cyst capsule spreading the liquid in the tissues surrounding the THA, and in the abdomen. Thanks to this simple procedure, the second stage treatment consisted of a relatively usual THA revision. The patient recovered completely from the treatment and returned to pain-free full activities of daily living.

Modular Fluted Tapered Stems in Aseptic Revision Total Hip Arthroplasty.

BACKGROUND: Modular fluted tapered stems have become the most commonly employed category of femoral component in revision hip arthroplasty in North America as a result of favorable early results and simplicity of use. Despite wide adoption, the majority of published data are limited to relatively small series with modest follow-up. The goal of the current study was to determine the success rate and factors associated with success, failure, and complications of the use of modular fluted tapered stems in aseptic revision total hip arthroplasties (THAs) in a large patient cohort. METHODS: We identified 519 aseptic femoral revisions during which a modular fluted tapered stem was utilized. Clinical outcomes, Kaplan-Meier survivorship, radiographic outcomes, and complications were assessed. The mean age at revision arthroplasty was 70 years, the mean body mass index (BMI) was 29 kg/m, and the mean duration of follow-up was 4.5 years (range, 2 to 14 years). RESULTS: The mean Harris hip score (HHS) improved significantly from 51 points preoperatively to 76 points at 2 years (p < 0.001). This improvement was maintained at the last follow-up evaluation (mean HHS = 75 points). At the time of the most recent follow-up, 16 femoral revisions had been performed: 6 because of aseptic loosening, 4 because of infection, 3 because of instability, 2 because of periprosthetic fracture, and 1 because of stem fracture. The 10-year survivorship was 96% with revision for any reason as the end point and 90% with any reoperation as the end point. Of the patients who were alive and had not undergone revision at the time of final follow-up, 12 had stem subsidence but all but 1 of these stems had stabilized after subsiding. Postoperative complications were noted in 12% of the cases. Repeat revision due to femoral component loosening was not correlated with the preoperative bone-loss category or patient demographic factors. CONCLUSIONS: In this large series, femoral revision with a modular fluted tapered stem provided a high rate of osseointegration and sustained improvement in clinical scores at the time of the last follow-up. There was also a high rate of successful implant fixation across all categories of preoperative bone loss and an acceptable rate of complications. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tibial Tuberosity Anteromedialization for Patellofemoral Chondral Disease: Prognostic Factors.

BACKGROUND: Tibial tuberosity anteromedialization (TTA) is a well-established treatment option for patellofemoral chondral disease that is resistant to nonoperative treatment. However, the prognostic factors of this procedure are unknown. PURPOSE: To analyze the prognostic factors correlated with the midterm outcomes of TTA for patellofemoral chondral disease and determine the survivorship. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Indications of TTA for chondral disease included skeletal maturity, age <65 years, 7 points (34.6% of knees) in the multiple regression model was associated with age >45 years (odds ratio [OR], 10.4; 95% CI, 2.0-55.0) and increased femoral anteversion (OR, 7.9; 95% CI, 1.4-44.1). A Kujala score of <80 points (61.5% of knees) was associated with age >45 years (OR, 12.0; 95% CI, 2.6-56.2) and foot pronation (OR, 5.1; 95% CI, 1.3-20.4). Patient satisfaction of <7 of 10 points (32.1% of knees) was associated with positive postoperative patellofemoral crepitus (OR, 3.6; 95% CI, 1.1-11.7). The Kaplan-Meier survivorship of TTA with dissatisfaction (<5/10 points) as an end point was 94% at 43 months, 88% at 77 months, and 77% at 108 months. CONCLUSION: Overall, good outcomes and survivorship (77% at 108 months) were obtained in this case series. However, 25.6% of the patients would not undergo the surgery again. Increased age, increased femoral anteversion, foot pronation, and postoperative patellofemoral crepitus were identified as negative prognostic factors.

Long-Term Results After Total Knee Arthroplasty with Contemporary Rotating-Hinge Prostheses.

BACKGROUND: Total knee arthroplasty (TKA) with a rotating-hinge prosthesis is considered a salvage procedure. While excellent immediate stability is achieved, the historically high failure rate has tempered its use. The goal of this study was to determine clinical outcomes, radiographic results, and survivorship after TKA with contemporary rotating-hinge components. METHODS: We identified 408 consecutive TKAs performed with rotating-hinge components for nononcologic indications from 2002 to 2012 at a single academic institution. Two hundred and sixty-four knees (65%) had rotating-hinge TKA components implanted for aseptic etiologies, while 144 knees (35%) were managed with the components in 2-stage reimplantation following infection. Rotating-hinge TKA implants were used for complex primary procedures in 74 knees (18%) and as a revision construct in 334 knees (82%). Clinical outcomes were assessed with the Knee Society scoring system, survivorship analyses, and cumulative incidence of revision. The mean age of the patients at the time of the index arthroplasty was 69 years, and the mean duration of follow-up was 4 years (range, 2 to 12 years). RESULTS: At the most recent follow-up, the mean Knee Society knee score had increased from 51 points preoperatively to 81 points (p < 0.0001), and the mean Knee Society functional score had increased from 26 to 36 points (p < 0.0001). At a mean of 4 years, loosening of components was observed in 13 (3.7%) of 349 knees. At the most recent follow-up, 59 revision procedures and 25 reoperations had been performed. The cumulative incidence of any revision was 9.7% at 2 years and 22.5% at 10 years. The cumulative incidence of revision for aseptic loosening was 1.7% at 2 years and 4.5% at 10 years. Metaphyseal cones were used in 114 knees (28%). Survivorship analysis revealed a trend toward a lower risk of revision (hazard ratio [HR] = 0.69; 95% confidence interval [CI] = 0.39 to 1.22; p = 0.20) and reoperation (HR = 0.51; 95% CI = 0.22 to 1.19; p = 0.12) in patients with metaphyseal cones, despite their use in the most severe of bone defects. CONCLUSIONS: Contemporary rotating-hinge TKA implants had a low 10-year cumulative incidence of revision for aseptic loosening of 4.5%. Greater use of metaphyseal fixation has aided this improvement. Patients can expect substantial improvements in clinical outcomes with this revision strategy. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Fusion of the First Metatarsophalangeal Joint and Second to Fifth Metatarsal Head Resection for Rheumatoid Forefoot Deformity.

The goals of the present study were to evaluate the mid-term results of first metatarsophalangeal joint fusion combined with second to fifth metatarsal head resection in rheumatoid forefoot deformity and identify the prognostic factors. The inclusion criteria were 2010 American College of Rheumatology and/or European League Against Rheumatism criteria for rheumatoid arthritis; symptomatic forefoot deformity; first metatarsophalangeal joint fusion and second to fifth metatarsal head resection; and a minimum of 4 years of follow-up data available. The patients were evaluated using the Disease Activity Score 28 for rheumatoid arthritis, Health Assessment Questionnaire for Rheumatoid Arthritis, Foot Function Index, forefoot American Orthopaedic Foot and Ankle Society scale, and weightbearing radiographs. Different pre-, intra-, and postoperative variables were investigated to identify the prognostic factors. Sixty-two patients (89 feet) with a mean age of 60.8°± 9.4 years and 85.5°± 22.4 months of follow-up data were included. The preoperative American Orthopaedic Foot and Ankle Society scale score was 33.4 ± 16 points and improved significantly (p < .001) after surgery (mean 82.9 ± 11.7 points). The mean Foot Function Index improved significantly (p < .001) from 131.6 ± 37.4 to 77.4 ± 46.3 points at the last follow-up visit. Only the revision surgery variable was significantly (p = .02) related to poor outcomes. Revision was necessary in 8 feet (9%). This procedure produced satisfactory results. Poor outcomes were significantly related to the necessity for revision surgery for nonunion, malunion, inadequate metatarsal resection, and painful hardware.

Chronic knee extensor mechanism lesions in total knee arthroplasty: a literature review.

Knee extensor mechanism rupture is a serious complication of total knee arthroplasty (TKA). Its prevalence ranges from 1 to 10% and it is commonly observed as a chronic multifactorial pathology with the patellar tendon as the most common site of rupture. Knee extensor mechanism reconstruction can be performed using allogenic or synthetic grafts. In the literature it is still not clear whether one of these techniques is superior to the other and the choice is usually tailored to the patient case by case. Allografts allow better restoration of the anatomical landmarks, whereas the mesh technique is more reproducible and the graft does not elongate over time. Allografts carry an increased risk of infection compared with synthetic reconstructions, while the mesh technique is cheaper and more readily available. In this paper, we review the etiology, diagnosis and treatment of this pathology, drawing on the most recent literature.

Instability After Total Knee Arthroplasty.

Instability is one of the most common causes of failure after total knee arthroplasty. Although there are several contributing causes, surgical error and poor implant design selection contribute. For this reason, an accurate diagnosis is fundamental and is largely based on a thorough history and physical examination. In general, tibiofemoral instability can be classified into 3 different patterns: flexion instability, genu recurvatum, and extension instability. In this article, these 3 patterns are reviewed in greater depth.

Avoiding Hip Instability and Limb Length Discrepancy After Total Hip Arthroplasty.

Two complications after total hip arthroplasty (THA) are hip instability and limb length discrepancy; instability is a common indication for revision THA. The goal of a successful THA is to maximize impingement-free range of motion, recreate appropriate offset, and equalize limb length discrepancies to produce a pain-free and dynamically stable THA. In this article, the patient risk factors for dislocation and limb length discrepancy, key elements of the preoperative template, the anatomic landmarks for accurate component placement, the leg positions for soft tissue stability testing, and the management of postoperative instability are reviewed.