A systematic review and meta-analysis of hybrid vs. cemented stems - which method is more optimal for revision total knee arthroplasty?

INTRODUCTION

The number of primary and revision Total Knee Arthroplasty (TKA) cases are expected to increase in future. There are various advantages and disadvantage to employing either of the two main types of stem fixation methods - cemented or hybrid technique. This review aimed to study the most optimal fixation method for revision TKAs by comparing radiological outcomes and re-revision rates.

METHODS

A systematic review and meta-analysis was performed using PubMed and Cochrane Library from 2010 to identify studies explicitly comparing outcomes between cemented against hybrid fixation revision TKA techniques, with a minimum follow up of at least 24 months. A total of 8 studies was included in this review. Egger's test and visual inspection of the funnel plot did not reveal publication bias.

RESULTS

There was no statistically significant difference in radiological failure and loosening (OR 0.79, CI 0.37-1.66, I2 = 29%, p = 0.22), all causes of re-revision (OR 1.03, CI 0.73-1.44, I2 = 0%, p = 0.56) and aseptic revision (OR 0.74, CI 0.27-2.02, I2 = 0%, p = 0.41) between cemented and hybrid techniques. Functional and pain outcomes compared between the two fixation techniques were largely similar across the studies included in this meta-analysis.

CONCLUSION

Despite a trend favouring hybrid stems in revision TKA, current evidence revealed that radiological outcomes and re-revision rates are largely similar between cemented and hybrid fixation techniques.

Current Concepts on the Clinical and Economic Impact of Periprosthetic Joint Infections

Total joint arthroplasty (TJA) is a common procedure performed throughout the entire world in hopes of alleviating debilitating hip or knee pain. The projected number of TJAs performed in the United States alone is projected to exceed 1.9 million by 2030 and 5 million by 2040. With the significant increase in TJA performed, more periprosthetic joint infections (PJIs) are likely to be encountered. PJIs are a devastating complication of TJA. The economic and clinical burden must be understood and respected to minimize occurrence and allow optimal patient outcomes.

Appearance and evolution of radiolucent lines below the tibial implant in primary total knee arthroplasty

BACKGROUND

The aim of this study was to evaluate total knee arthroplasty (TKA) radiographically to detect the occurrence of radiolucent lines (RLL) under the tibial base plate and to determine what type of RLL may have a correlation with aseptic loosening (AL). The study had two hypotheses: (1) RLLs may have different radiological aspects and evolutions in time depending of different factors (2) Signs of micro- and/or macro-mobility of the implant are necessary before diagnosing aseptic loosening of the tibial component.

METHODS

Retrospective cohort study of 774 patients operated with a Vanguard TKA (Zimmer Biomet, Warsaw, IN, US) from 2007 to 2015. RLLs were recorded in a database and described according to their radiological aspect, localization, time of apparition, progression and eventual evolution to AL. Other collected parameters were pre- and post-operative HKA angles, amount of post-operative HKA correction, surgical, clinical and demographic data.

RESULTS

178/774 TKAs (23%) showed RLLs under the tibial base plate including 9 (1.2%) tibial implants needing revision for AL. Three different types and two aspects of RLLs were observed. Important deformity corrections or undercorrected implants were recognized as a mechanical risk factor for loosening. Elderly women with osteoporosis and young men with important pre-operative deformities were identified as clinical risk factors for RLLs.

CONCLUSIONS

RLLs are frequently present at the epiphyseal bone/implant interface after total knee arthroplasty, but do not mean the implant is loose. They can be considered a sign of reduced epiphyseal surface fixation due to micro mobility of the tibial implant. Aseptic loosening can be observed radiologically when signs of macro-mobility of the implant are present at the metaphyseal level.

LEVEL OF EVIDENCE

III.

Metaphyseal cones combined with diaphyseal impaction grafting provide good outcomes and survival in a complex revision total knee arthroplasty: a matched comparative analysis

PURPOSE

To compare clinical and radiological outcomes, implant survivorship at a minimum of 1-year follow-up using metaphyseal trabecular cones with or without impaction grafting in a complex revision TKA.

METHODS

A retrospective comparative matched analysis was performed and 15 patients who underwent revision surgery using the combination of porous trabecular metaphyseal cone and diaphyseal impaction grafting (MC-IBG) were matched with a group of 13 patients who also underwent revision surgery using metaphyseal cone (MC) without impaction grafting. All included patients presented severe bone defect (AORI 2,3) and a rotating-hinge prosthesis were implanted.

RESULTS

Both groups were comparable regarding the baseline demographic and clinical data. Patients had previously undergone a mean of 4 (range, 2-12) and 3 (range, 2-5) previous procedures in the MC-IBG and MC groups, respectively. The indications for revision were aseptic loosening in 11 (73.3%) and 11 (84.6%) patients; prosthetic joint infection in 4 (26.7%) and 2 (15.4%) in the MC-IBG and MC groups, respectively. There was no significant difference in the mean postoperative Knee Society Score between the study groups (p = 0.806). Overall, 4 patients had further revision. Two patients were revised in the MC-IBG group, one patient for aseptic loosening and the second one after 2 episodes of instability. Two patients in the MC group presented prosthetic joint infection and underwent a two-stage reimplantation. No significant difference was observed between the study groups at comparison (p = 0.92).

CONCLUSION

Trabecular metal cones with diaphyseal impaction grafting provide an alternative technique in a complex revision TKA surgery with early clinical and radiographic success.

Revision total knee arthroplasty results in financial deficits within the Swiss healthcare system

PURPOSE

Revision total knee arthroplasty (RTKA) results in high costs with inadequately low reimbursement in different healthcare systems. Therefore, a financial analysis was performed comparing costs and reimbursements of primary total knee arthroplasty (PTKA) versus RTKA using financial and total knee arthroplasty-register data from a large tertiary hospital, the Cantonal Hospital of St. Gallen (KSSG), Switzerland.

METHODS

All PTKA and RTKA performed between January 2012 and September 2019 at the KSSG were included. Financial and TKA-register data for each case were collected, including detailed cost allocation, reimbursement, patients' insurance status, type and indication for surgery and length of hospital stay. RTKA was further subdivided in one-stage and two-stage RTKA. Direct hospital costs were analyzed and compared to reimbursement in both groups. Cost-coverage ratios were calculated.

RESULTS

730 PTKA and 106 RTKA were included. The RTKA group contained 66 one-stage and 40 two-stage RTKA. Cost-coverage ratio for PTKA and RTKA showed to be 110.9% and 81.3%, respectively. Cost-coverage ratio was lower for two-stage RTKA than for one-stage RTKA with 74.1% and 92.3%, respectively.

CONCLUSION

RTKA leads to financial deficits especially for tertiary hospitals within the Swiss healthcare system. Restructuring of the reimbursements for PTKA and RTKA should be considered in favor of RTKA. Otherwise, tertiary hospitals will face a growing financial burden with the constantly increasing annual number of RTKA procedures, predominantly performed in this type of hospitals.

LEVEL OF EVIDENCE

III.

Metaphyseal Metal Sleeves for Reconstruction of Severe Knee Bone Defects: Excellent Survival Rate at a Mean Follow-Up of 6.4 Years

OBJECTIVE

Management of bone loss in complex primary and revision total knee arthroplasty is key to the surgeries. Metaphyseal metal sleeves have been increasingly used recently to reconstruct severe knee metaphyseal bone defects. This study aimed to investigate the outcomes of the metaphyseal sleeve reconstructing Anderson Orthopedic Research Institute (AORI) type II and type III bone defects of knee joint.

METHODS

From 2014 to 2019, a total of 44 knees were enrolled in this clinical retrospective study after the screening, including seven cases of primary TKA and 37 cases of revision TKA. The types of bone defects involved in this study were AORI types II and III, and did not involve AORI type I bone defects. Patients' knee function preoperatively and postoperatively as well as quality of life were recorded and analyzed. Analysis included the American Knee Society Score (KSS), hospital for special surgery knee score (HSS), the Western Ontario and McMaster Universities (WOMAC) index, the Short Form 12 (SF-12) health survey, visual analogue scale score, and radiographic assessment with a mean follow-up of 6.4 years. Paired t-tests were used to determine the significance of changes in clinical scores and knee mobility.

RESULTS

A mean follow-up of 77.2 (±17.6, standard deviation [SD]) months was performed, and none of the patients underwent knee revision for infection or aseptic loosening. At the last follow-up, the KSS knee score changed statistically from 37.1 (±19.7) preoperatively to 86.5 (±13.6, SD, p < 0.001) postoperatively and the KSS function score from 32.7 (±24.0) preoperatively to 78.3 (±15.6, SD, p < 0.001) postoperatively. The knee mobility improved from a mean of preoperative 72.61° (±33.42°, SD) to 108.52° (±24.15°, SD, p < 0.001). Postoperative radiographs showed that the host bone was tightly integrated with the metaphyseal metal sleeve, and there was no obvious translucent line formation around the sleeve. Of the patients, 86.4% had a postoperative satisfaction score ≥8 (10-point scale).

CONCLUSION

At the mean follow-up of 6.4 years, the survival rate of the metaphyseal sleeves was 100%. Metaphyseal sleeves combined with cementless stems is an excellent and viable option for reconstruction of AORI type II and type III bone defects of the knee.

Does the geriatric nutritional risk index predict complication rates and implant survivorship in revision total joint arthroplasty?

INTRODUCTION

Malnutrition is associated with poorer outcomes after revision total joint arthroplasty (rTJA), though no universal metric for assessing malnutrition in rTJA patients has been reported. This study sought to determine if malnutrition as defined by the Geriatric Nutritional Risk Index (GNRI) can independently predict short-term complication rates and re-revision risk in patients undergoing rTJA.

METHODS

All patients ≥ 65 years old undergoing rTJA from 2011 to 2021 at a single orthopaedic specialty hospital were identified. Preoperative albumin, height, and weight were used to calculate GNRI. Based on the calculated GNRI value, patients were stratified into three groups: normal nutrition (GNRI > 98), moderate malnutrition (GNRI 92-98), and severe malnutrition (GNRI < 92). Chi-squared and independent samples t-tests were used to compare groups.

RESULTS

A total of 531 rTJA patients were included. Patients with normal nutrition were younger (p < 0.001), had higher BMI (p < 0.001). After adjusting for baseline characteristics, patients with severe and moderate malnutrition had longer length of stay (p < 0.001), were less likely to be discharged home (p = 0.049), and had higher 90-day major complication (p = 0.02) and readmission (p = 0.005) rates than those with normal nutrition. 90-day revision rates were similar. In Kaplan-Meier analyses, patients with severe and moderate malnutrition had worse survivorship free of all-cause re-revision at 1-year (p = 0.001) and 2-year (p = 0.002) follow-up compared to those with normal nutrition.

CONCLUSION

Moderate and severe malnutrition, as defined by GNRI, independently predicted higher complication and revision rates in rTJA patients. This suggests that the GNRI may serve as an effective screening tool for nutritional status in patients undergoing rTJA.

Local adiposity may be a more reliable predictor for infection than body mass index following total knee arthroplasty: a systematic review

PURPOSE

Improved understanding of the factors that predispose TKA patients to infection has considerable economic and medical impact. BMI is commonly used as a proxy for obesity to determine the risk of postoperative infection. However, this metric appears to be fraught with inconsistency in this application. BMI is a simple calculation which provides general insight into body habitus. But it fails to account for anatomic distribution of adipose tissue and the proportion of the mass that is skeletal muscle. Our objective was to review the literature to determine if local adiposity was more predictive than BMI for infection following TKA.

METHODS

A database search was performed for the following PICO (Population, Intervention, Comparison, and Outcome) characteristics: local measurements of adiposity (defined as soft tissue thickness or fat thickness or soft tissue envelope at the knee) in patients over 18 years of age treated with total knee arthroplasty used to determine the relationship between local adiposity and the risk of infection (defined as prosthetic joint infection or wound complication or surgical site infection). Quality was assessed using the GRADE framework and bias was assessed using ROBINS-I .

RESULTS

Six articles (N=7081) met the inclusion criteria. Four of the six articles determined that adiposity was more associated with or was a better predictor for infection risk than BMI. One of the six articles concluded that increased adiposity was protective for short term infection and that BMI was not associated with the outcome of interest. One of the six articles determined that BMI was more strongly associated with PJI risk than soft tissue thickness.

CONCLUSION

The use of adiposity as a proxy for obesity in preoperative evaluation of TKA patients is an emerging concept. Although limited by heterogeneity, the current literature suggests that local adiposity may be a more reliable predictor for infection than BMI following primary TKA.

LEVEL OF EVIDENCE

IV systematic review.

Peripheral Nerve Catheter Reduces Postoperative Opioid Consumption and Pain in Revision Total Knee Arthroplasty

Background

Patients undergoing revision total knee arthroplasty (rTKA) have historically received high doses of opioids during the perioperative period. As awareness of opioid use has heightened, opioid administration has continuously decreased. This study aimed to evaluate if peripheral nerve catheter (PNC) use in rTKA reduces opiate consumption while maintaining similar pain control and postoperative function levels.

Methods

A retrospective review of 354 patients who underwent rTKA between July 2019 and January 2022 was conducted. Fifty total patients who received an adductor canal PNC were propensity-matched 1:1 to a control group of 50 patients that did not receive a PNC. To assess the primary outcome of opiate consumption, nursing documented opiate administration events were converted into morphine milligram equivalents per 24-hour interval. Postoperative pain and functional status were assessed using the verbal rating scale for pain and the Activity Measure for Post-Acute Care scores, respectively.

Results

Compared to the control group, the PNC group demonstrated significantly lower overall inpatient opiate consumption (98.68 ± 117.03 vs 176.69 ± 203.47 morphine milligram equivalents; 44.15% decrease, P = .021) and lower verbal rating scale pain scores at 60 to 72 hours postoperatively (4.85 ± 1.24 vs 5.83 ± 1.35; 16.81% decrease, P = .038). There was no significant difference in Activity Measure for Post-Acute Care scores postoperatively (raw score: 19.41 ± 3.61 vs 19.46 ± 3.18; 0.26% decrease, P = .952). Finally, the PNC cohort was significantly less likely to be readmitted within 90 days after surgery (0.0% vs 12.0%; P = .012).

Conclusions

In rTKA patients, PNC can significantly reduce inpatient opioid consumption while maintaining a comparable functional recovery and superior pain control.

Level III Evidence

Retrospective Cohort Study.

Short-term results of the uncemented triathlon total knee arthroplasty: a large cohort single-centre comparative study

BACKGROUND

The purpose of this study is to assess the short-term survivorship of a new uncemented TKA design in a high-volume centre to evaluate the safety of this design prior to widespread adoption.

METHODS

We performed a retrospective cohort study of all primary TKAs (cemented and uncemented) between May 2018 and May 2019. Primary outcome variables included aseptic revision, all-cause revision, time to revision, operative time and radiological outcomes. Predictor variables considered included age, gender, BMI, ASA, implant type (cruciate-retaining, posterior-stabilised or totally-stabilised) and the use of cemented or uncemented implants.

RESULTS

There were 300 cemented TKAs and 249 uncemented TKAs (Triathlon, Stryker Inc., Mahwah, NJ) implanted. The mean follow-up for all cases was 31.6 months (minimum follow-up 2 years). Of the entire 549 implants only 4 were revised. Two of these were for infection, 1 was for patellar maltracking and 1 was for knee stiffness. All 4 revisions occurred in the cemented cohort. The aseptic revision rate in the cemented cohort was 0.7% compared to 0.0% in the uncemented cohort (p = 0.298). Operative times were significantly reduced in the uncemented cohort from 57.9 to 51.7 min (p < 0.001). There were 8/300 (2.6%) patients with RLLs in the cemented cohort and 4/249 (1.6%) patients with RLLs in the uncemented cohort (p = 0.56).

CONCLUSION

The uncemented Triathlon TKA demonstrates excellent survivorship at short-term follow-up when compared to the cemented Triathlon TKA, thus eliminating any potential clinical concerns with this novel implant in the early post-operative phase.

Radiographic and clinical analysis of a Porous-coated metaphyseal cone for revision total Knee arthroplasty

BACKGROUND

The aim of this study was to evaluate the radiographic and clinical outcomes of a recently introduced metaphyseal cone system for revision TKA.

METHODS

73 revision TKAs in 72 patients were retrospectively reviewed. All patients had a minimum of 2-year clinical follow-up (mean 34.1 months; range 24.0 to 50.3 months). 114 Metaphyseal cones (64 tibial and 50 femoral) of a single manufacturer were implanted. The most common indications for revision were aseptic loosening (56.9%), second stage reimplantation for periprosthetic joint infection (PJI; 26.4%), and instability (12.5%). All femoral and tibial stems were press-fit cementless stems.

RESULTS

Ten of 72 patients underwent re-revision: six for infection (8.3%), two for instability (2.8%), one (1.4%) for patellar tendon rupture and one (1.4%) for femoral component loosening (a cone was not utilized at index revision). Two patients had loose cones (one with an isolated tibial cone and one with both femoral and tibial cones) associated with loose implants but declined re-revision. Aseptic survivorship of our patient cohort free from any re-revision surgery was 95.9% at 2 years (95% CI 87.4-98.7%) and 96.5% of cones demonstrated radiographic evidence of osseointegration. At 2-years, the Knee Society Score (KSS) improved from a mean of 17.2 points preoperatively to 57.8 points (p <.0001).

CONCLUSIONS

Porous-coated metaphyseal cones from this manufacturer demonstrate excellent aseptic survivorship and radiographic evidence of osseointegration similar to prior designs when used with cementless stems.

Soft Tissue Procedures in the Multiply Operated on Knee Replacement Patient

In the multiply operated on knee replacement, no one soft tissue procedure is vastly superior to another. The most extensive literature available is in relation to muscle flaps, which will continue to be the workhorse technique for orthopedic and plastic reconstructive surgeons for the foreseeable future. Closed incision negative pressure wound therapy may prove to be a superior method in time but further large-scale studies are required to expand our understanding of this technique. The continued use of a combination of these techniques, tailored to the specific patient, is likely to be the best approach to the multiply operated on knee into the future.

Revision TKA with a distal femoral replacement is at high risk of reinfection after two-stage exchange for periprosthetic knee joint infection

PURPOSE

Megaprosthetic distal femoral reconstruction (DFR) is a limb-salvage procedure to address bone loss following two-stage revision for periprosthetic knee joint infection (PJI). The purpose of this study was to analyze the survival of DFR compared to hinged total knee arthroplasty (TKA). It was hypothesized that DFR was associated with a poorer survival.

METHODS

In this retrospective single-center study, 97 subjects who underwent two-stage revision of chronic knee PJI were included. Among these, 41 were DFR. The diagnosis of PJI was established using the Musculoskeletal Infection Society (MSIS) criteria. Implant survival was calculated using Kaplan-Meier method and compared with the log-rank test as well as multivariate Cox regression at a minimum follow-up period of 24 months.

RESULTS

The median follow-up period was 59 (interquartile range (IQR) 45-78) months. Overall, 24% (23/97) of patients required revision surgery for infection. The infection-free survival of rotating hinge revision TKA was 93% (95% Confidence Interval (CI) 86-100%) at five years compared to 50% (95% CI 34-66%) for DFR. In multivariate analysis, the risk factors for reinfection were DFR reconstruction (HR 4.7 (95% CI 1-22), p = 0.048), length of megaprosthesis (HR 1.006 (95% CI 1.001-1.012), p = 0.032) and higher BMI (HR 1.066, 95% CI 1.018-1.116), p = 0.007). 10% (4/41) of patients undergoing DFR underwent amputation to treat recurrent infection.

CONCLUSION

Megaprosthetic DFR as part of a two-stage exchange for PJI is a salvage treatment that has a high risk for reinfection compared to non-megaprosthetic TKA. Patients must therefore be counseled accordingly.

LEVEL OF EVIDENCE

Retrospective observational study, Level IV.

Good to excellent long-term survival of a single-design condylar constrained knee arthroplasty for primary and revision surgery

PURPOSE

The purpose of the study was to determine the long-term survivorship, functional outcomes of a single-design condylar constrained (CCK) TKA in primary and revision cases as well as to assess specific risk factors for failure. It was hypothesized that primary CCK TKA had a better survival than revision knees.

METHODS

One hundred and forty three patients who underwent revision TKA (n = 119) or complex primary TKA (n = 24) using a single-design condylar constrained knee system (Genesis CCK, Smith & Nephew) performed at a single institution between 1999 and 2008 were retrospectively included. The median follow-up amounted to 11.8 years (IQR 10.3-14.4). Implant survivorship was analyzed using Kaplan-Meier survival estimates and multivariate Cox regression analysis to identify risk factors for failure. Function was determined using the Oxford Knee Score (OKS).

RESULTS

The implant survival was 86.4% after five, 85.5% after ten and 79.8% at 15 years. A reduced implant survivorship was found in males (HR 5.16, p = 0.001), smokers (HR 6.53, p = 0.004) and in obese patients (HR 2.26, p = 0.095). Patients who underwent primary TKA had a higher revision-free implant survivorship compared to revision TKA at 15 years (100% vs. 76%, p = 0.036). The main cause for re-revision was infection in 10% of all revision TKA performed with the CCK design included, while no case was revised for instability. The median OKS was 39 (IQR 35-44) in 102 patients available for long-term functional outcome.

CONCLUSION

CCK implants are associated with excellent long-term survival when used in primary TKA; however, survival was worse when used during revision TKA. Males, smokers, obese patients and are at higher risk for revision. While instability and aseptic loosening were rare, infection remains a major concern.

LEVEL OF EVIDENCE

Level IV, retrospective observational study.

Highly cross-linked polyethylene (HXLPE) is equivalent to conventional polyethylene (CPE) in total knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

The benefits of HXLPE in total knee arthroplasty (TKA) have not been as evident as total hip arthroplasty (THA). A systematic review and meta-analysis to assess the impact of highly-crosslinked polyethylene (HXLPE) on TKA outcomes compared to conventional polyethylene (CPE) is described.

METHODS

All studies comparing HXLPE with CPE for primary TKA were included for analysis. The minimum dataset included revision rates, indication for revision, aseptic component loosening and follow-up time. The primary outcome variables were all-cause revision, aseptic revision, revision for loosening, radiographic component loosening, osteolysis and incidence of radiolucent lines. Secondary outcome measures included postoperative functional knee scores. A random-effects meta-analysis allowing for all missing data was performed for all primary outcome variables.

RESULTS

Six studies met the inclusion criteria. In total, there were 2,234 knees (1,105 HXLPE and 1,129 CPE). The combined mean follow-up for all studies was 6 years. The aseptic revision rate in the HXLPE group was 1.02% compared to 1.97% in the CPE group. There was no difference in the rate of all-cause revision (p = 0.131), aseptic revision (p = 0.298) or revision for component loosening (p = 0.206) between the two groups. Radiographic loosening (p = 0.200), radiolucent lines (p = 0.123) and osteolysis (p = 0.604) was similar between both groups. Functional outcomes were similar between groups.

CONCLUSION

The use of HXLPE in TKA yields similar results for clinical and radiographic outcomes when compared to CPE at midterm follow-up. HXLPE does not confer the same advantages to TKA as seen in THA.

A Review of Periprosthetic Tibial Fractures: Diagnosis and Treatment

Periprosthetic fracture occurring during or after total knee arthroplasty is a rare injury. Literature concerning periprosthetic tibial factures is sparse, and there is limited guidance for evidence-based management. This review aims to provide readers with an overview of the epidemiology, risk factors, and classification of these fractures. Management includes nonoperative treatment of nondisplaced fractures, fixation for those with stable implants, and revision for those with loose implants.

Accuracy of joint line restoration based on three-dimensional registration of the contralateral tibial tuberosity and the fibular tip

Purpose

To assess a novel method of three-dimensional (3D) joint line (JL) restoration based on the contralateral tibia and fibula.

Methods

3D triangular surface models were generated from computed tomographic data of 96 paired lower legs (48 cadavers) without signs of pathology. Three segments of the tibia and fibula, excluding the tibia plateau, were defined (tibia, fibula, tibial tuberosity (TT) and fibular tip). A surface registration algorithm was used to superimpose the mirrored contralateral model onto the original model. JL approximation and absolute mean errors for each segment registration were measured and its relationship to gender, height, weight and tibia and fibula length side-to-side differences analyzed. Fibular tip to JL distance was measured and analyzed.

Results

Mean JL approximation did not yield significant differences among the three segments. Mean absolute JL error was highest for the tibia 1.4 ± 1.4 mm (range: 0 to 6.0 mm) and decreased for the fibula 0.8 ± 1.0 mm (range: 0 to 3.7 mm) and for TT and fibular tip segment 0.7 ± 0.6 (range: 0 to 2.4 mm) (p = 0.03). Mean absolute JL error of the TT and fibular tip segment was independent of gender, height, weight and tibia and fibula length side-to-side differences. Mean fibular tip to JL distance was 11.9 ± 3.4 mm (range: 3.4 to 22.1 mm) with a mean absolute side-to-side difference of 1.6 ± 1.1 mm (range: 0 to 5.3 mm).

Conclusion

3D registration of the contralateral tibia and fibula reliably approximated the original JL. The registration of, TT and fibular tip, as robust anatomical landmarks, improved the accuracy of JL restoration independent of tibia and fibula length side-to-side differences.

Level of evidence

IV

Conversion total knee arthroplasty: A case complexity between primary and revision total knee arthroplasty

BACKGROUND

Conversion total knee arthroplasty (TKA) may represent a more complex procedure compared with primary TKA. The purpose of this study was to compare 30-day complications between conversion TKA and primary, non-conversion TKA as well as between conversion TKA and revision TKA on a national scale using a multi-center surgical registry.

METHODS

Adult patients undergoing conversion TKA from 2006 to 2018 were identified in the National Surgical Quality Improvement Program database and were compared with patients who underwent primary TKA and aseptic revision TKA. In this analysis, 30-day complications were assessed. Bivariate analyses, including chi-squared and analysis of variance, and multivariate logistic regressions were performed.

RESULTS

Of 299,065 total patients undergoing knee arthroplasty, 1,310 (0.4%) underwent conversion TKA, 275,470 (92.1%) underwent primary TKA, and 22,285 (7.5%) underwent revision TKA. Following adjustment, patients who underwent conversion TKA were more likely to have increased risks of any complications (P < 0.001), mortality (P = 0.021), wound complications (P < 0.001), cardiac issues (P = 0.018), bleeding requiring transfusion (P < 0.001), and reoperation (P = 0.002) relative to primary TKA patients. Compared with patients who underwent revision TKA, conversion TKA patients were less likely to have septic complications (P = 0.009).

CONCLUSION

Conversion TKA is associated with significantly higher rates of complications compared with primary, non-conversion TKA, but less risk of sepsis compared with revision TKA. Because current reimbursement classifications do not account for the case complexity of a conversion TKA, new classifications should be implemented with reimbursements for conversion TKA approximating reimbursements for revision TKA.

A Modified Technique for Artificial Fusion in Unreconstructable Revision Total Knee Arthroplasty

Knee arthrodesis is an acceptable treatment that leads to a stable joint with a lower rate of recurrence of infection in periprosthetic joint infections. One of the major problems in some revision cases is the bone loss that interferes with the bony union; therefore, some studies suggest artificial arthrodesis, which does not require bony union. The present descriptive retrospective study was conducted by reviewing the medical records of patients with periprosthetic joint infection complications. Patient satisfaction was evaluated after artificial arthrodesis, based on the visualized analog scale score and Oxford Knee Score. The mean Oxford Knee Score was 28, and the mean limb length discrepancy was 11 mm. In this new method, the length of hospitalization and leg length discrepancy was reduced, limb alignment and rotation was adjustable, and periprosthetic joint infection was controlled in nearly all patients.

Long-term results of revision total knee arthroplasty using a rotating hinge implant

BACKGROUND

Rotating hinge implants are commonly used in revision total knee arthroplasty (TKA) in the setting of significant ligamentous instability or bone deficiency. These highly constrained implants have been associated with variable clinical outcomes and uncertain long-term survivorship. The aim of this study is to establish long-term functional outcomes, radiographic results, and survivorship after revision TKA with a rotating hinge implant.

METHOD

This is a retrospective study of prospectively collected data of 41 consecutive patients undergoing revision TKA with rotating hinge components and minimum 10-years follow-up. The study included 22 females (53.7%) and 19 males (46.3%) with a mean age of 66.6 ± 8.5 years. Clinical outcomes recorded included the Oxford Knee Score (OKS) preoperatively and at latest follow-up. Range of motion, implant survivorship, and complications were also recorded. Predefined radiological outcomes were obtained using plain radiographs.

RESULTS

There was a significant improvement in OKS after revision TKA with a rotating hinge implant compared to preoperative scores (40.7 ± 4.2 vs. 21.4 ± 4.9 respectively, p < 0.001). At latest follow-up, mean range of motion was 111.5° ± 9.3° and mean overall limb alignment was 0.2° ± 2.0° varus. Implant survivorship at minimum 10-year follow-up was 90.2%. Radiographic lucent lines were observed in 14 patients (34.1%).

CONCLUSION

Revision TKA with a rotating hinge implant leads to satisfactory clinical outcomes and very good implant survivorship at long-term follow-up. Surgeons should have a low threshold to use these versatile implants in complex revision knee arthroplasty.

Use of porous custom-made cones for meta-diaphyseal bone defects reconstruction in knee revision surgery: a clinical and biomechanical analysis

INTRODUCTION

Although the practice of metaphyseal reconstruction has obtained successful clinical and radiological results in revision total knee surgery, off-the-shelf devices aren't an effective solution for all patients as they do not cover the full range of clinical possibilities. For this reason, during severe knee revisions, custom-made porous titanium cementless metaphyseal cones are nowadays employed as alternative to traditional surgeries. The aim of this study is to understand the benefits gained by the use of the custom-made cones against the performance of more traditional techniques, such as the use of cemented or cementless stems. Thus, a retrospective study on eleven patients and a biomechanical finite element analysis (FEA) was developed, based upon three clinical cases of the clinical analyzed cohort.

MATERIALS AND METHODS

Eleven patients underwent staged total knee arthroplasty revision with the use of 16 custom-made cones to correct severe femoral and tibial meta-diaphyseal bone defects. Clinical scores and range of movement were observed during the follow-up period (mean follow-up 26 ± 9.4 months). Reason for surgery was periprosthetic joint infection (PJI) in eight patients and post-traumatic osteomyelitis in the other three patients. Three patients previously affected by PJI were selected among the eleven patients of the clinical population. For those patients, bone geometries and implants during surgery were replicated in silico and analyzed during different daily activities. For the same patients, as alternative solution for surgery, the use of cemented or cementless stems was also simulated by FEA. Stress patterns in different region of interest and risk of fracture in the bone were calculated and compared.

RESULTS

No loosening, component migration, or mismatches between preoperative planning and intraoperative findings were clinically registered. Biomechanical results demonstrated that the use of custom-made cones induces a more homogeneously distributed bone stress than the other two techniques that concentrate the stress in spotted regions. The risk of fracture is comparable between the use of custom-made cones and cemented technique, while press-fit configurations increase the risk of fracture (more than 35%).

CONCLUSIONS

Based upon the clinical evidence and the findings after the FEAs, the practice of porous custom-made metaphyseal cones in severe revisions of knee arthroplasties is showing promising biomechanical results. The homogeneous stresses distributions and the lower bone stress gradient could justify a reduction of bone fractures and the risk of implant loosening which could be the explanation to the successful clinical outcomes.

Management of aseptic failure of the mobile-bearing Oxford unicompartmental knee arthroplasty

BACKGROUND

Unicompartmental knee arthroplasty (UKA) accounts for 9.1% of primary knee arthroplasties (KAs) in the UK. However, wider uptake is limited by higher revision rates compared with total knee arthroplasties (TKA) and concerns over subsequent poor function. The aim of this study was to understand the revision strategies and clinical outcomes for aseptic, failed UKAs at a high-volume centre.

METHODS

This was a retrospective, single-centre cohort study of 48 patients (31 female, 17 male) with 52 revision UKAs from 2006 to 2018. Median time to revision was 67 (range 4-180) months. Indications for revision were progression of osteoarthritis (n = 31 knees, 59.6%), unexplained pain (n = 10 knees, 19.2%), aseptic loosening (n = 6 knees, 11.5%), medial collateral ligament incompetence (n = 3 knees, 5.8%) and recurrent bearing dislocation (n = 2 knees, 3.8%). Technical details of surgery, complications and functional outcome were recorded.

RESULTS

Failed UKAs were revised to primary TKAs (n = 29 knees, 55.8%), revision TKAs (n = 9 knees, 17.3%), bicompartmental KAs (n = 11 knees, 21.2%), or unicompartmental-to-unicompartmental KAs (n = 3 knees, 5.8%). Median follow up was 81 (range 24-164) months. Four patients (7.7%) died from unrelated causes. No re-revisions were identified. Surgical complications required re-operation in five knees (9.6%). Median Oxford Knee Score at latest follow up was 38 (range 9-48) points and median EQ5D3L index 0.707 (range -0.247 to 1.000).

CONCLUSIONS

Aseptic, revision UKA at a high-volume centre had good clinical outcomes. Bicompartmental KA demonstrated excellent function and should be considered an alternative to TKA for progression of osteoarthritis for appropriately trained surgeons.

Difficult to treat: are there organism-dependent differences and overall risk factors in success rates for two-stage knee revision?

OBJECTIVES

Failure after two-stage procedure for periprosthetic joint infection (PJI) is a rare, but devastating complication. Some authors assume a correlation of underlying organisms and recurrence rate. Methicillin-resistant Staphylococci (MRS) and other organisms (quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida) are meant to be "difficult to treat" (DTT) with an inferior outcome for two-stage revision. In addition to the type of bacteria, some more risk factors seem to be present. The aim of this study was (1) to detect a difference of reinfection rates between reinfection-causing groups of bacteria ["difficult to treat" (DTT), "easy to treat" (ETT) and methicillin-resistant staphylococci (MRS)] after a two-stage procedure, and (2) find overall risk factors for reinfection in a standardized long (spacer insertion for at least 6 weeks) two-stage procedure for periprosthetic knee infection.

METHODS

One hundred and thirty-seven two-stage revisions for periprosthetic knee infection were performed at one tertiary referral center. Finally, 96 patients could be included for analyses. Possible risk factors (comorbidities, prior surgery, etc.) and the types of organisms were documented. Quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida were classified as "difficult to treat" (DTT). Methicillin-resistant Staphylococci were summarized as "MRS", all other organism are summarized as "easy to treat" (ETT). Statistical analyses included univariate analysis (t test, Fisher's exact test, Chi square test) and logistic regression analysis.

RESULTS

There were no statistical significant differences in recurrent infection rates between organism groups (DTT vs. ETT, p = 0.674; DTT vs. MRS, p = 0.705; ETT vs. MRS, p = 0.537). Risk factors seem to be "need of revision after first stage" (p = 0.019, OR 5.62) or completed second stage (p = 0.000, OR 29.07), numbers of surgeries (p = 0.028) and alcohol abuse (p = 0.019, OR 5.62).

CONCLUSIONS

Revision needed during or after a two-stage exchange, numbers of surgeries and alcohol abuse are risk factors for recurrence, a different recurrence rates between organism-groups cannot be shown. The absence of significant differences in recurrence rates points to the importance of the individuality of each periprosthetic infection case: a reduction of necessary surgeries (with a thorough debridement, appropriate antibiotic addition to spacers) and the control of comorbidities (alcohol abuse) appear to be essential components of a two-stage exchange.

Hybrid stems are superior to cemented stems in revision total knee arthroplasty: a systematic review and meta-analysis of recent comparative studies

INTRODUCTION

The demand for revision total knee arthroplasty (TKA) has grown significantly in recent years. The two major fixation methods for stems in revision TKA include cemented and 'hybrid' fixation. We explore the optimal fixation method using data from recent, well-designed comparative studies.

METHODS

We performed a systematic review of comparative studies published within the last 10 years with a minimum follow-up of 24 months. To allow for missing data, a random-effects meta-analysis of all available cases was performed. The odds ratio (OR) for the relevant outcome was calculated with 95% confidence intervals. The effects of small studies were analyzed using a funnel plot, and asymmetry was assessed using Egger's test. The primary outcome measure was all-cause failure. Secondary outcome measures included all-cause revision, aseptic revision and radiographic failure.

RESULTS

There was a significantly lower failure rate for hybrid stems when compared to cemented stems (p = 0.006) (OR 0.61, 95% CI 0.42-0.87). Heterogeneity was 4.3% and insignificant (p = 0.39). There was a trend toward superior hybrid performance for all other outcome measures including all-cause re-revision, aseptic re-revision and radiographic failure.

CONCLUSION

Recent evidence suggests a significantly lower failure rate for hybrid stems in revision TKA. There is also a trend favoring the use of hybrid stems for all outcome variables assessed in this study. This is the first time a significant difference in outcome has been demonstrated through systematic review of these two modes of stem fixation. We therefore recommend the use, where possible, of hybrid stems in revision TKA.

Management of the bone loss by metaphyseal sleeves in primary and revision knee arthroplasty: clinical experience and outcome after forty three cases

AIM OF THE STUDY

Management of metaphyseal bone loss in complex primary and revision TKA is a challenge for surgeons. Out of various types of bony defects, large metaphyseal bone loss (AORI types IIB and III) requires special augments in the form of cones or sleeves. The aim of this study is to assess the reliability of metaphyseal sleeves, in dealing with massive bone defects to provide stability for immediate weight bearing and also to check short to mid-term survivorship of metaphyseal sleeves in Asian population by assessing various parameters and complications.

METHODS

This is a retrospective study that includes 36 patients (43 knees), operated from 2011 to 2019. Patients with AORI type IIB (large metaphyseal bone defect) and AORI type III (metaphyseal defect with compromised collateral ligaments) were included. We included both the primary and revision knee arthroplasties in our study. Our interest in this study was to look for incidence of intra-operative iatrogenic fracture on the one hand, and post-operative complications in the form of peri-prosthetic joint infection and aseptic loosening on the other hand. Knee Society Score (KSS) was used to assess improvement in patient's clinical outcome. SPSS version 23 was used to process data.

RESULTS

The average age of patients in our study was 59.4 (SD 9.78) years. Male to female ratio was 21:15. The average follow-up was 5.42 (SD 2.24) years with the longest follow up of nine years. Metaphyseal sleeves were used in 12 primary TKA and 31 revision TKA. During surgery, iatrogenic fracture of tibial condyle was encountered in three patients (6.9%), all were managed without any intervention and union was achieved in all cases. There was not a single case with aseptic loosening as per radiological criteria in our study. Peri-prosthetic joint infection (PJI) was encountered in a single case (2.3%). Pre-op Knee Society Score (KSS) was 36.21 (SD 7.43) where as it improved to 92.00 (SD 5.66), six months after surgery. Also the range of flexion was increased from 76.83^o (SD 14.07^o) to 122.91^o (SD 4.84^o).

CONCLUSION

In our study, metaphyseal sleeves showed excellent short to mid-term survivorship in AORI types IIB and III boneloss in Asian population. These results are comparable to various studies conducted on North American and European population. Metaphyseal sleeve is a reliable tool in the armamentarium of the arthroplasty surgeon. It is user friendly implant and provides immediate stability to allow full weight-bearing mobilization.

Revision total knee arthroplasty for patellar dislocation in patients with malrotated TKA components

PURPOSE

Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty (TKA). The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. We sought to understand the reasons for post-arthroplasty patellar dislocation and the clinical outcomes of patients in whom it occurs.

METHODS

This is a retrospective cohort study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision TKAs. Patient demographics, dislocation etiology, presurgical deformity, intraoperation component position, complications, reoperation, and Knee Society Scores (KSS) were collected.

RESULTS

Twenty patients (21 knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD 44.4), and the average time from dislocation to revision was 3.38 months (SD 2.81). Seventeen knees (80.9%) had internal rotation of the tibial component and seven knees (33.3%) had combined internal rotation of both the femoral and tibial components. Fifteen knees (71.4%) were treated with a condylar constrained implant at the time of revision, and five knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean KSS was 86.2.

CONCLUSION

Revision TKA following patellar dislocation for patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes.

Management of periprosthetic fracture following total knee arthroplasty- a retrospective study to decide when to fix or when to revise?

PURPOSE

Periprosthetic fractures around total knee arthroplasty are relatively rare complication comprises to 0.3-2.5%. But these injuries are often complex and challenging for the surgeons due to ageing population in conjunction with severe osteoporosis. The management option varies from conservative to internal fixation or revision surgery. Thus this study was conducted to analyze the results of various methods of treatment of periprosthetic fractures following TKA and to form the optimal treatment guidelines for fixation or revision.

MATERIAL AND METHODS

51 cases diagnosed with periprosthetic fracture were enrolled and underwent surgical intervention. Type of primary prosthesis, interval between TKA and periprosthetic fracture, type of fracture, prosthesis stability and mode of fixation of fracture, any revision surgery and complication were noted.

RESULTS

The mean age of all patients was 65.89 years. The mean interval between the index surgery and periprosthetic fracture was 6 years (Range 2 months to 10 years) in male and 18.5 months (Range 4 days to 7 years) in female. 44 (86%) fractures were femoral, 4 (8%) fractures were tibial and 3 (6%) fractures were of patella. The mean knee society score (KSS) & oxford knee score (OKS) were found to be good for revision group as compared to the fixation group at final follow up.

CONCLUSION

In presence of poor bone stock, far distal fracture configuration, comminution, severe osteoporosis, difficulty in achieving stability with plates & old age-revision TKA is a viable option with stemmed components.

Comparison of infection eradication rate of using articulating spacers containing bio-inert materials versus all-cement articulating spacers in revision of infected TKA: a systematic review and meta-analysis

PURPOSE

To assess the infection eradication rate when using two types of articulating spacers (prosthetic articulating spacers and all-cement articulating spacers) in two-stage revision of infected total knee arthroplasty (TKA).

METHODS

We comprehensively searched PubMed, Embase, and the Cochrane Library databases and performed a systematic review and meta-analysis of retrospective comparative studies assessing two types of articulating spacers. A quality assessment of the included studies was performed following the STROBE statement.

RESULTS

Thirty retrospective studies, including a total of 821 knees, were identified. The pooled infection control rates in stage I were as follows: 0.98 (95% confidence interval [CI], 0.97 to 1.00) and 0.98 (95% CI, 0.96 to 0.99) for the prosthetic articulating spacer group and all-cement articulating spacer group, respectively. The pooled postoperative reinfection rate was 0.05 (95% CI, 0.03 to 0.08) for the prosthetic spacer group and 0.03 (95% CI, 0.01 to 0.06) for the all-cement spacer group. Results of the subgroup analyses showed that the weight of the antibiotic cement, antibiotic type, mean period of spacers in situ, postoperative antibiotic treatment period, and postoperative antibiotic treatment approach had no effect on the reinfection rates (p < 0.05).

CONCLUSIONS

Compared to all-cement articulating spacers, articulating spacers containing bio-inert materials have a similar infection control rate but a higher postoperative reinfection rate. Although the 95% CIs of reinfection rates in the two groups overlapped, our results indicate that articulating spacers containing bio-inert materials may be associated with higher reinfection rates and poorer clinical outcomes than all-cement articulating spacers.

Preoperative blood transfusion associated with increased length of stay and increased postoperative complications after revision total knee arthroplasty

Currently, the impact of preoperative transfusion on postoperative morbidity following revision total knee arthroplasty (TKA) is unknown. A retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was performed and included patients who underwent revision TKAs. Postoperative complications were analyzed. A total of 6,849 patients were included. Patients who received a preoperative blood transfusion were found to have an increased risk of developing 3 of 17 adverse events. Although overall complication rates remain relatively low, orthopedic surgeons should counsel their patients on the implications of preoperative blood transfusions on post-operative outcomes.

A comparison of relative value units in revision hip versus revision knee arthroplasty

The purpose of this study was to compare the: 1) RVUs; 2) lengths-of-surgery; 3) RVU per minute between revision hip (THA) and knee (TKA) arthroplasties; and 4) perform an annualized surgeon cost analysis. Using the ACS-NSQIP from 2008 to 2015, 8081 revision TKAs, 7233 THAs were compared. Revision THA had greater mean RVUs (30.27 vs. 27.10 RVUs, p < 0.001), operative times (152 vs. 149 min, p < 0.001), and RVU/minute (0.3 vs. 0.2 RVUs per minute, p < 0.001). Cost analysis yielded and annual $89,922.73 difference. Revision THA, therefore, is reimbursed at a significantly higher "hourly rate," when compared to revision TKA.

Correlation of tibial bone defect shape with patient demographics following total knee revision

Background

Bone defects of the proximal tibia following revision total knee arthroplasty (TKA) are challenging to manage, but must be addressed to provide lasting stability. This paper will categorize tibial bone defects into shape groups and correlate resulting groups to patient demographic data.

Methods

Retrospective analysis of four hundred and four patients post revision TKA between January 2005 and February 2014 was conducted. One hundred and eighteen met the inclusion criteria and were subcategorized by defect shape on their post-operative lateral and anterior-posterior (AP) radiographs. The subgroups of defect shape were subsequently analyzed with Fisher's exact test and one way ANOVA.

Results

Trapezoidal shaped defects were the most common in both radiographic views, and the magnitude of the defect at the top joint line varied significantly amongst shape groups in both AP and lateral views. Trapezoid shaped defects were correlated with smaller defect top lengths in both views. There was no statistical correlation between defect shape BMI, TIV and reason for revision in lateral view. However, T-bilateral defect shapes were correlated with higher BMIs in AP view.

Conclusion

A volumetric classification system of tibial defects is necessary for preoperative planning in revision TKA. Common tibial bone defect shape groups were identified and analyzed in AP and lateral radiographs after revision TKA. Trapezoidal defects were the most common, and all other shapes followed a pattern of proximal enlargement tapering distally. Trapezoidal defects were smaller than other shapes and AP T-bilateral shaped defects were correlated with higher BMIs.

Unexplained pain following total knee arthroplasty: Is rotational malalignment the problem?

BACKGROUND

Malrotation of tibial and femoral components is a potential source of pain following total knee arthroplasty (TKA). This study aimed to 1) compare component rotation in TKA patients with unexplained pain versus a control group with well-functioning TKAs and 2) investigate the relationship between TKA component rotation and pain.

METHODS

Seventy one patients with unexplained pain after primary TKA were compared to a control cohort of 41 well functioning TKA patients. Both groups underwent post-operative computed tomography (CT) scans to assess component rotation. Findings were compared between the painful and control TKA groups.

RESULTS

We found no difference in femoral component rotation between the painful and control groups (mean 0.6° vs 1.0° external rotation (ER), p=0.4), and no difference in tibial component rotation (mean 11.2° vs 9.5° internal rotation (IR), p=0.3). Also, there was no difference in combined mal-rotation (tibial+femoral rotation) between the groups (mean 10.5° vs 8.5°IR, p=0.25). Fifty-nine percent of patients in the painful group had tibial component rotation >9°IR vs 49% in the control group.

CONCLUSION

In the largest study yet on component rotation after TKA, we found no difference in the incidence of tibial, femoral, or combined component mal-rotation in painful versus well-functioning TKAs. Tibial component IR relative to the junction of the medial to middle thirds of the tibial tubercle appears to be common in patients with well-functioning TKAs. The significance of slight tibial IR should be interpreted with caution when evaluating the painful TKA. Level III retrospective case-control study.

Rotating hinge prosthesis for complex revision total knee arthroplasty: A review of the literature

INTRODUCTION

The rotating hinge prosthesis was originally used and designed as a primary total knee arthroplasty implant, but was hampered due to poor outcomes and catastrophic failures. Newer rotating hinge implants can be utilized in complex revision total knee arthroplasties when appropriately indicated, but their outcome data is very difficult to interpret due to the strict and varied indications for use and subsequently small number of procedures performed. The goal of this review is to evaluate the current evidence on large cohort, rotating hinge knee prostheses used in the revision setting, in order to provide a clearer understanding of the indications, outcomes and complications.

METHODS

The PubMed database was utilized to search the available literature regarding "hinged knee," or "rotating hinge" devices. Exclusion criteria included papers focusing on primary arthroplasty, revision for oncologic issues, one-stage revision for infection or studies with less than fifty cases.

RESULTS

Review of 115 abstracts after initial search, led to ten studies in the literature that met our inclusion and exclusion criteria. The data shows that rotating hinge knee implants have good survivorship ranging from 51% to 92.5% at 10 years post-operatively. Complication rates range from 9.2% to 63% with infection and aseptic loosening as the most common complications.

CONCLUSION

Rotating hinge knee prostheses are most commonly indicated for infection, aseptic loosening, instability and bone loss in the literature. They have good outcome scores and survivorship, but continue to have high complication and revision rates. The implant is a good option when utilized appropriately for patients that are not candidates for less constrained devices.

A classification-based approach to the patella in revision total knee arthroplasty

Background

There is a paucity of data to guide management of the patella in revision total knee arthroplasty (RTKA). The purpose of this study was to review our experience with patellar management in RTKA.

Methods

We retrospectively reviewed 422 consecutive RTKAs at a minimum of 2 years (mean, 42 months). Patellar management was guided by a classification that considered stability, size, and position of the implanted patellar component, thickness/quality of remaining bone stock, and extensor mechanism competence.

Results

Management in 304 aseptic revisions included retention of a well-fixed component in 212 (69.7%) and revision using an all-polyethylene component in 46 (15.1%). Patella-related complications included 5 extensor mechanism ruptures (1.6%), 3 cases of patellar maltracking (1.0%), and 2 periprosthetic patellar fractures (0.7%). Of 118 2-stage revisions for infection, an all-polyethylene component was used in 88 (74.6%), patelloplasty in 20 (16.9%), and patellectomy in 7 (5.9%). Patella-related complications included 4 cases of patellar maltracking (3.4%), 3 extensor mechanism ruptures (2.5%), and 1 periprosthetic patellar fracture (0.8%).

Conclusions

Septic revisions required concomitant lateral releases more frequently (38.1% vs 10.9%; P < .02) but had a similar rate of patellar complications (6.8% vs 3.3%; P = .40). No cases required rerevision specifically for failure of the patellar component. Patients who had a patelloplasty had worse postoperative Knee Society functional scores than those with a retained or revised patellar component. In most aseptic RTKAs, a well-fixed patellar component can be retained. If revision is required, a standard polyethylene component is sufficient in most septic and aseptic revisions. Rerevisions related to the patellar component are infrequent.

Revision total knee arthroplasty using a custom tantalum implant in a patient following multiple failed revisions

The number of revision total knee arthroplasty procedures performed annually is increasing and, subsequently, so is the number of patients presenting following a failed revision. Rerevising a total knee arthroplasty after one or more failed revision procedures presents many challenges, including diminished bone stock for prosthetic fixation. “Off the shelf” implants may not offer the best alternative for reconstruction. We present the case of a 55-year-old patient who required a rerevision total knee arthroplasty following multiple failed revisions with severe femoral and tibia bone loss. We describe a novel technique we employed to improve component fixation within the compromised bone stock.

Clinical and radiological results of femoral head structural allograft for severe bone defects in revision TKA--a minimum 8-year follow-up

BACKGROUND

Proper treatment of bone loss is essential for the long term durability of revision TKA. However, the method of choice in managing large bone defects is still under debate. We therefore assessed the mid to long term clinical and radiographic results of revision TKA using a fresh frozen femoral head allograft and a standard condylar implant or varus-valgus constrained prosthesis with a diaphyseal-engaging stem.

METHODS

We retrospectively reviewed the records of 27 patients who had undergone revision TKA between August 1997 and March 2003 using a fresh frozen femoral head allograft and a standard condylar implant or varus-valgus constrained prosthesis with a diaphyseal-engaging stem. The median follow-up period was 107 months (range, 96-157 months).

RESULTS

Clinical evaluation revealed that the mean range of motion had increased from 71° to 113° and the mean Hospital for Special Surgery knee score had improved from 46 to 83 points. The overall tibio-femoral angle improved from varus 7.3° to valgus 6.l°. In 26 out of 27 knees, union was demonstrated at an average of seven months postoperatively, and there were no cases of collapse, disease transmission or stress fractures. In one knee, an infection recurred.

CONCLUSIONS

Our results demonstrate that femoral head allografts in treatment of severe bone defects are reliable and durable. If possible, less constrained prostheses with diaphyseal-engaging stems should be chosen for increased durability.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.