Intraosseous Vancomycin May Not Be Helpful in Aseptic Revision Knee Arthroplasty: A Single-Surgeon Consecutive Case Series

BACKGROUND

Infection after aseptic revision total knee arthroplasty (TKA) has been reported from 9% to 14%. Intraosseous (IO) vancomycin infusion has decreased the risk of infection after primary TKA. The results of this additional prophylaxis were evaluated in aseptic revision TKA.

METHODS

In this prospective, single-surgeon study of 20 consecutive patients having aseptic revision TKA, 500 milligrams of vancomycin in 120 mL of saline were infused into the tibia prior to incision, in addition to intravenous (IV) cefazolin. There were 18 men and 2 women who had a mean age of 67 years (range, 47-79), and mean body mass index of 34.4 (range, 25.9-51.2). The knees were aspirated in the operating room prior to IV and IO antibiotics. The outcomes were infections at 90 days requiring reoperation and complications from the infusion.

RESULTS

Three of the 20 aseptic revisions had early prosthetic joint infection, 2 with gram-negative organisms and one with coagulase-negative Staphylococcus. All had debridement, liner exchange and IV antibiotic treatment, but 1 patient eventually had an above knee amputation. No patient had total body "erythema syndrome", but 1 patient had transient facial flushing. Six patients had a transient elevation of serum creatinine including 3 with an abnormal preoperative serum creatinine.

CONCLUSION

In this small series of aseptic revision TKA, there was no added benefit of IO vancomycin infusion, but there were no infections with methicillin-resistant Staphylococcus aureus. Additional studies are needed before this technique should be routinely recommended.

Predictors of Reinfection in Prosthetic Joint Infections Following Two-Stage Reimplantation

BACKGROUND

Two-stage reimplantation is an effective treatment for periprosthetic joint infection (PJI). Many factors are involved in the variable success of this procedure. The purpose of this study is to examine the relationship between patient risk factors, comorbidities, and the pathogen on reinfection rates following two-stage reimplantation.

METHODS

We evaluated 158 patients treated for PJI from 2008-2019. Only patients who had completed a two-stage exchange were included. Patient demographics, comorbidities, laboratory values, time-to-reimplantation, pathogen, antibiotic sensitivities, host status, and reinfection rates were assessed. Multivariate analysis was performed to identify correlation between risk factors and reinfection. A P-value < .05 was considered statistically significant.

RESULTS

31 patients experienced a reinfection (19.6%). There was a statistically significant association between infection with Methicillin Sensitive Staphylococcus Aureus (MSSA) and reinfection (P = .046). Patients with a reinfection also had a significantly greater median serum C-reactive protein (CRP) level (12.65 g/dL) at the time of diagnosis compared to patients without a reinfection (5.0 g/dL) (P = .010). Median Erythrocyte Sedimentation Rate (ESR) (56 in no re-infection and 69 in re-infection) and time-to-reimplantation (101 days in no reinfection and 141 days in reinfection) demonstrated a trend toward an association with re-infection but were not statistically significant (P = .055 and P = .054 respectively).

CONCLUSION

As the number of arthroplasties continue to rise, PJIs are increasing proportionately and represent a significant revision burden. Elevated C-reactive protein (CRP) levels and Methicillin Sensitive Staphylococcus aureus (MSSA) infection were strongly associated with failure of a two-stage reimplantation. While not statistically significant with our numbers, there were strong trends toward an association between elevated Erythrocyte Sedimentation Rate (ESR), longer time-to-reimplantation, and reinfection.

Current Reconstruction Options in Periprosthetic Fractures Around the Knee

Background:

Periprosthetic fractures are a rare complication after total knee arthroplasty (TKA). However, the incidence of these fractures is growing after the increasing number of TKAs performed every year and the progressive aging of the population. In addition, the surgical treatment and peri-operative management of these complications are demanding, representing a challenge for the orthopedic surgeon.

Significance:

A thorough understanding of these fractures and a correct classification are necessary in order to select the most suitable surgical treatment. The aim of this review was to analyze the epidemiology, classification, diagnosis, surgical treatment, and outcomes of periprosthetic knee fractures in order to give an exhaustive overview.

Results:

Reduction and internal fixation with locking plates or intramedullary nails represents the preferred option in case of a stable prosthetic implant. Conversely, in case of loose tibial and/or femoral component, implant revision is mandatory. Conservative treatment is rarely indicated.

Conclusion:

A deep understanding of the characteristics and patterns of periprosthetic knee fractures, and the determination of the stability of the prosthetic implant are necessary in order to establish the correct treatment.

Clinical Outcomes in Isolated Tibial Revision With Cruciate Retaining Total Knee Arthroplasty

BACKGROUND

Tibial component loosening is one of the most common modes of failure in contemporary total knee arthroplasty (TKA). Limited literature is available on the outcomes of isolated tibial revision with retention of the cruciate retaining (CR) femoral component. The purpose of this study was to determine the results of isolated tibial revisions in CR TKA.

METHODS

We identified 135 patients who underwent an isolated tibial revision after a primary CR TKA from our institutional registry between January 2007 and January 2017. The mean time between the primary and revision was 2.9 years (range 0.1-15.4). Revision with a press-fit stem was performed in 79 patients and 56 patients were revised with a fully cemented stem. Patients were evaluated at a minimum of two years using Knee Society Score, Knee Injury and Osteoarthritis Score for Joint Replacement, and radiography. Implant survivorship was determined using Kaplan-Meier survival analysis.

RESULTS

At a mean follow-up of 5.1 years, there were six (4.4%) repeat revisions: three for periprosthetic infection (2.2%), two for instability (1.5%), and one for a fractured tibial stem (0.7%). The mean Knee Society Score and Knee Injury and Osteoarthritis Score for Joint Replacement increased from 51.6 and 56.1 preoperatively to 90.1 and 89.7 after surgery (P < .001). Survivorship free of repeat revision for any cause was 93.3% at 5 years, and aseptic revision survivorship was 95.8% at 5 years. No implants were radiographically loose.

CONCLUSION

In patients with isolated tibial loosening and a well-fixed and well-positioned CR femoral component, isolated tibial revision provides excellent early to midterm implant survivorship and clinical outcomes with a low risk of instability and recurrent tibial loosening.

The Epidemiology of Hip and Knee Primary and Revision Arthroplasties during the COVID-19 Pandemic

BACKGROUND

The purpose of this study was to provide a comprehensive assessment of the impact of the COVID-19 pandemic on the epidemiology of primary and revision arthroplasties of the hip and knee joint.

METHODS

This study compared the data on knee and hip arthroplasty procedures from 2 hospitals (primary and revision) conducted in two periods: the period of the COVID-19 pandemic in Poland (from 4 March 2020 to 15 October 2020) and the corresponding period prior to the pandemic (from 4 March 2019 to 15 October 2019). We compared the epidemiological data, demographic data, and hospital stay duration data from these two periods.

RESULTS

Our analysis demonstrated that the total number of hip arthroplasties conducted in 2020 decreased by 26% in comparison with 2019. In the case of knee arthroplasties, the total number of procedures in the evaluated period in 2020 decreased by 44%. Our study also showed that the mean time of hospital stay for orthopedic patients following hip or knee arthroplasty was 22.87% shorter. The female-to-male patient ratio decreased between the analyzed periods, and this was 22.96% lower during the pandemic.

CONCLUSION

The COVID-19 pandemic in these two hospitals in Poland led to reduced numbers of hip and knee replacement procedures, shorter hospital stays, and a decreased female-to-male patient ratio. The mean age of patients undergoing hip or knee arthroplasty remained unchanged during the national lockdown with respect to the pre-pandemic figure.

Does a lateral tibial plateau fracture (Takeuchi type III) occuring during opening wedge high tibial osteotomy induce a higher revision rate to total knee arthroplasty

BACKGROUND AND AIM

High tibial osteotomies (HTO) are effective procedures to treat younger patients affected by moderate but symptomatic arthritis. Open-wedge HTO (OW-HTO) is more often performed compared to a closing wedge osteotomy to treat varus arthritis of the knee due to a lower incidence of complications and better results: lateral hinge fracture (LHF) is the most common complication of OW-HTO. Intra articular fractures of the lateral tibial plateau (Takeuchi type III) appear as a particularly serious complication due to its extension to the subchondral bone of the compartment towards which the load is shifted. Aim of our study, is to assess if an intra articular fracture of the lateral tibial plateau occurring during an OW-HTO leads to an higher risk of failure and to an early conversion to a total knee arthroplasty.

METHODS

Between January 2013 and December 2018 114 patients underwent OW-HTO at our Orthopaedic Department. All the patients underwent the same surgical procedure performed by a skilled knee surgeon: a subcutaneous-medial locked plate (Tomofix®, Synthes, Solothurn, Switzerland) has been used in all the procedures to stabilize the osteotomy. Clinical and radiographic follow up has been performed at one, three, six and twelve months postoperatively afterwards annually. We retrospectively reviewed all the intra operative fluoroscopy of patients to detect those affected by an intra articular fracture of the lateral tibial plateau occurred intra operatively.

RESULTS

A LHF occurred in 11 out of 114 patients (9.65%) who underwent an OW-HTO; in particular nine patients (7.9%) had a Type III LHF. In all cases such complication has been detected intra operatively. In the subgroup of patients who experienced an intra articular fracture of the tibial plateau at the last follow up only one patients underwent to a revision with a total knee arthroplasty; in other words, the survivorship of an OW-HTO complicated by a LHF type III resulted 89% at a mean follow-up of 5 years. In 103 patients without an intraoperative fracture, the percentage of patients free from revision at the last follow up resulted of 92%.

CONCLUSIONS

Takeuchi type III fracture is an uncommon but serious complication to manage: in our case series we found that an early recognition and a correct treatment of this occurrence don't lead to a premature conversion to a knee arthroplasty if compared with an uncomplicated osteotomy. Further studies are necessary to establish specific subjective outcomes after OW-HTO burdened by an intra articular fracture of the lateral plateau.

Manipulation Under Anesthesia After Total Knee: Who Still Requires a Revision Arthroplasty?

BACKGROUND

Stiffness after total knee arthroplasty (TKA) is a multifactorial complication involving patient, implant, surgical technique, and rehabilitation, occasionally necessitating manipulation under anesthesia (MUA) or revision. Few modern databases contain sufficient longitudinal information of all factors. We characterized MUA after primary TKA and identified independent risk factors for revision TKA after MUA from the American Joint Replacement Registry.

METHODS

We retrospectively reviewed primary TKAs for American Joint Replacement Registry patients ≥65 years from January 1, 2012 to 31 March, 2019. We linked these to the Centers for Medicare and Medicaid Services database to identify MUA and revision TKA procedure codes. We compared groups with chi-squared testing, identifying independent risk factors for subsequent revision with binary logistic regression presented as odds ratios with 95% confidence intervals.

RESULTS

Of 664,604 primary TKAs, 3918 (0.6%) underwent MUA after a median of 2.0 ± 1.0 months. Revision surgery occurred in 131 (3.4%) MUA patients after a median of 9.0 months. Timing of MUA was not different between revision and no revision patients (P = .09). Patients undergoing MUA compared to no MUA were older (age 71.5 vs 70.7, P < .01), predominantly female (63.9% vs 61.2%, P < .01), current/former tobacco users (24.2% vs 13.3%, P < .01), with osteoarthritis diagnoses (98.0% vs 84.3%, P < .01). Independent risk factors for revision after MUA were male gender (1.56, 1.09-2.22).

CONCLUSION

The incidence of MUA after primary TKA is low (0.6%) in Medicare patients ≥65 years of age; 3.4% progress to revision after a median of 9 months. Being male was significantly associated with revision TKA after MUA.

The Use of Calcium Sulphate beads in Periprosthetic Joint Infection, a systematic review

Purpose: To assess the use of calcium sulphate (CS) beads in the management of knee and hip periprosthetic joint infections (PJI) in terms of outcomes, complications and re-infection rates.

Methods: A search of NICE healthcare database advanced search (HDAS) was conducted from its year of inception to October 2019 with the keywords: “Calcium Sulphate Beads” or “Calcium Sulfate Beads” or “Antibiotics beads” or “Stimulan” and “Arthroplasty” or “Hip Replacement” or “Knee Replacement” and “Periprothetic joint infection” or “Debridement, Antibiotics and implant retention” or “Revision”. A quality assessment was performed using the NIH study Quality Assessment Tool for case series.

Results: Out of relevant 74 articles, 5 articles met the inclusion criteria. Variable outcomes and success rates have been reported in most of the patients. A small number of wound discharges and heterotrophic ossification (HO) were reported, which are occasionally symptomatic. Hypercalcemia is identified as a potential risk with the use of CS beads especially with doses over 40 cc per operation. The influence of CS beads on reinfection rate is reported in 4 out of 5 articles. Due to the case-mix and heterogenicity of the patients involved and the causative microorganism reported as well as varied procedures are undertaken including one and two stages revision and Debridement, Antibiotics and implant retention (DAIR), the influence of CS beads varied from high success to poor outcome. The poor outcome is higher if the primary procedure for the management of hip and knee PJI is DAIR rather than full revision.

Conclusions: The use of CS beads in the treatment of PJI is a useful technique in delivering high doses of antibiotics locally. A favourable outcome is reported when antibiotics loaded CS is used as an adjuvant to revision procedure for PJI in hip and knee arthroplasty compared to its use as an adjuvant to DAIR procedure. There has been an increase in complications when higher volumes of beads are used, especially in subcutaneous structures and in high-risk patients. Another possible theoretical and unreported complication of CS beads is accelerating the wear rate in the artificial joint due to the possibility of causing abrasion to the bearing surfaces. The current evidence is not enough to indicate the superiority of antibiotic-loaded CS beads as an adjuvant for the treatment of PJI in Hip and Knee arthroplasty.

Do Antibiotic Intramedullary Dowels Assist in Eradicating Infection in Two-Stage Resection for Septic Total Knee Arthroplasty?

BACKGROUND

Evidence suggests approximately 40% of intramedullary (IM) canals are culture positive at resection for infected knee arthroplasty. While commonly utilized, no clinical data on the efficacy of antibiotic-eluding IM dowels exist. We quantified treatment success with and without the use of antibiotic-eluding IM dowels in two-stage treatment of periprosthetic knee infection using static and articulating antibiotic cement spacers.

METHODS

109 consecutive patients who underwent two-stage treatment for periprosthetic knee infection were reviewed. Treatment failure, defined as repeat resection before reimplantation or recurrent infection within 6 months of reimplantation, was evaluated based on spacer type and use of IM dowels, accounting for infection type and systemic host and local extremity grade.

RESULTS

After exclusions for confounds, articulating spacers without IM dowels were used in 49 (57.7%) cases, articulating spacers with IM dowels in 14 cases (16.5%), and static spacers with IM dowels in 22 (25.9%) cases. Treatment success regardless of infection classification was 85.7% for articulating spacers with IM dowels, 89.8% for articulating spacers without IM dowels, and 68.2% for static spacers with IM dowels (P = .074). In chronically infected poor hosts with compromised extremities, treatment success remained highest in patients with articulating spacers with (90.9%) or without (92.9%) IM dowels compared with static spacers with IM dowels (68.4%) (P = .061).

CONCLUSION

Findings suggest that the use of IM dowels did not enhance infection eradication above and beyond that observed for articulating spacers alone, including in the worst cases involving chronically infected poor hosts with compromised extremities.

The Use of Tantalum Metaphyseal Cones for the Management of Severe Bone Defects in Septic Knee Revision

BACKGROUND

Femoral and tibial massive bone defects are common findings in septic total knee revision and pose considerable challenges for the orthopedic surgeon. The aim of this study was to report the midterm clinical and radiographic outcomes with the use of tantalum cones for the management of massive bone defects after 2-stage knee revision.

METHODS

We retrospectively reviewed the medical records of 60 patients (mean age, 67.9 ± 8.8 years) treated with 94 tantalum cones associated with constrained or semiconstrained knee for massive bone loss (mean follow-up, 43.5 ± 17.4 months). In all cases, the indication was a staged revision for periprosthetic knee infection. Functional scores, radiographic outcomes, and implant survivorship were analyzed.

RESULTS

The mean Knee Society Score and Oxford Knee Score improved from 44.1 ± 7.4 and 19.2 ± 4.1 to 85.4 ± 5.6 and 38.4 ± 3.9 (P < .01), respectively. The mean flexion increased from 60.6° ± 15.5° to 96.8° ± 10.9° at the last evaluation (P < .01). The mean improvement in flexion contracture was 6.2 ± 8.0 (P < .01). Two failures (3.3%) due to periprosthetic knee infection recurrence were observed, but no cone-related mechanical failures were reported. The cone-related survival rate was 97.8%.

CONCLUSION

Excellent clinical and radiographic midterm outcomes were achieved with a low complication rate. Tantalum cones may be considered a safe and effective option in the management of massive bone defects also in septic knee revision surgery.

Is Selectively Not Resurfacing the Patella an Acceptable Practice in Primary Total Knee Arthroplasty?

BACKGROUND

To resurface or not to resurface the patella remains a controversy in total knee arthroplasty (TKA). The purpose of this study was to assess the long-term outcomes associated with selectively not resurfacing the patella.

METHODS

This was a historical cohort study of 15,497 patients with 21,371 primary TKA procedures performed at a single institution between 1985 and 2010. The cohort included 402 (2%) knees with unresurfaced patellae and 20,969 knees with all-polyethylene patellae designs. Reasons for not resurfacing the patella were documented. Multivariable Cox regression analyses were used to estimate the risk of complications and revisions among procedures with unresurfaced patellae.

RESULTS

According to the surgeon, reasons for not resurfacing were normal cartilage (226, 56%), young patient (30, 8%), thin patella (53, 13%), and surgeons' choice (93, 23%). In age, sex, and calendar year-adjusted analyses, the risk of complications (hazard ratio [HR]: 1.25, 95% confidence interval [CI]: 1.06, 1.46) and all-cause revisions (HR: 1.39, 95% CI: 1.02, 1.89) were significantly higher after TKA with unresurfaced patellae. However, after adjusting for femoral component types and operative diagnoses, these associations were no longer significant. The only group with significantly worse outcomes were those with a thin patellae with increased risk of complications (HR: 2.66, 95% CI: 1.70, 4.17) and revisions (HR: 5.94, 95% CI: 2.35, 15.02). Yet, the excess risk in the thin patellae group was mainly due to infections, and not related to unresurfaced patellae.

CONCLUSION

Selectively not resurfacing the patella seemed to provide similar results compared with routine resurfacing.

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.

Closed-Incision Negative-Pressure Therapy Versus Antimicrobial Dressings After Revision Hip and Knee Surgery: A Comparative Study

BACKGROUND

This study evaluates the efficacy of closed-incision negative-pressure therapy (ciNPT) in decreasing wound complications and surgical site infections (SSIs) after revision hip and knee surgery.

METHODS

A retrospective quality improvement analysis of 138 consecutive revision hip and knee operations performed by a single surgeon over a 34-month period was performed. ciNPT was used selectively in higher-risk patients with multiple risk factors for SSIs over the last 15 months of the study period. Rates of wound complications, SSIs, and reoperation were compared with patients treated with a sterile antimicrobial dressing.

RESULTS

Antimicrobial dressings were used in 108 patients, whereas ciNPT was used in 30 patients. Patients treated with ciNPT developed fewer overall wound complications (6.7% vs 26.9%, P = .024) and fewer total SSIs (3.3% vs 18.5%, P = .045) than patients treated with antimicrobial dressings. In addition, there were trends toward a lower rate of superficial wound dehiscence (6.7% vs 19.4%, P = .163), fewer deep periprosthetic joint infections (0.0% vs 9.3%, P = .118), and fewer reoperations (3.3% vs 13.0%, P = .191) among patients treated with ciNPT.

CONCLUSION

Our findings suggest that ciNPT may decrease wound complications and SSIs in patients undergoing revision hip and knee surgery.

The cement spacer with multiple indentations: increasing antibiotic elution using a cement spacer 'teabag'

We investigated whether the indentation of bone cement spacers used in revision of infected joint arthroplasty with a MacDonald dissector increased the elution of antibiotic in vitro. A total of 24 cement discs containing either 0.17 g (0.88% w/w), 0.25 g (1.41% w/w), or 0.33 g (1.75% w/w) gentamicin of constant size were made. Of these, 12 were indented with the dissector. Each disc was immersed in ammonium acetate buffer in a sealed container, and fluid from each container was sampled at zero, one, three, six, 24, 48 and 72 hours and at one, and two weeks. The concentration of gentamicin in the fluid was analysed using high performance liquid chromatography mass spectrometry. The fluid sampled at 72 hours from the indented discs containing 0.17 g gentamicin (0.88% w/w) contained a mean of 113 mcg/ml (90.12 to 143.5) compared with 44.5 mcg/ml (44.02 to 44.90) in the fluid sampled from the plain discs (p = 0.012). In discs containing 0.33 g gentamicin (1.75% w/w), the concentration eluted from the indented discs at 72 hours was a mean of 316 mcg/ml (223 to 421) compared with a mean of 118 mcg/ml (100 to 140) from the plain discs (p < 0.001). At two weeks, these significant differences persisted. At nine weeks the indented discs eluted a greater concentration for all gentamicin doses, but the difference was only significant for the discs containing 0.17 g (0.88% w/w, p = 0.006). However if the area under the curve is taken as a measure of the total antibiotic eluted, the indented discs eluted more gentamicin than the plain discs for the 0.17 g (0.88% w/w, p = 0.031), the 0.25 g (1.41% w/w, p < 0.001) and the 0.33 g (1.75% w/w, p < 0.001) discs. When preparing antibiotic spacers for use in staged revision arthroplasty surgery we recommend indenting the spacer with a MacDonald dissector to increase the elution of antibiotic.

The Effect of Insurance Type on Patient Access to Knee Arthroplasty and Revision under the Affordable Care Act

This study evaluated access to knee arthroplasty and revision in 8 geographically representative states. Patients with Medicaid were significantly less likely to receive an appointment compared to patients with Medicare or BlueCross. However, patients with Medicaid had increased success at making an appointment in states with expanded Medicaid eligibility (37.7% vs 22.8%, P=0.011 for replacement, 42.6% vs 26.9%, P=0.091 for revision), although they experienced longer waiting periods (31.5 days vs 21.1 days, P=0.054 for replacement, 45.5 days vs 22.5 days, P=0.06 for revision). Higher Medicaid reimbursement also had a direct correlation with appointment success rate for Medicaid patients (OR=1.232, P=0.001 for replacement, OR=1.314, P=0.014 for revision).

Patella tendon injuries secondary to cement spacers used at first-stage revision of infected total knee replacement

We describe a series of three patients who sustained patella tendon injuries in infected total knee arthroplasties following the use of a static cement spacer at first-stage knee revision. The patella tendon injuries resulted in significant compromise to wound healing and knee stability requiring multiple surgeries. The mid-term function was poor with an Oxford score at 24 months ranging from 12 to 20. Based on our experience, we advise caution in the use of static cement spacer blocks. If they are to be used, we recommend that they should be keyed in the bone to prevent patella tendon injuries.

The role of the popliteus tendon in total knee arthroplasty: a cadaveric study: SIGASCOT Best Paper Award Finalist 2014

PURPOSE

this study was conducted to investigate the influence of the popliteus tendon (PT) on the static stability of total knee arthroplasty (TKA).

METHODS

twenty knees were used. In 10 right knees, a cruciate-retaining (CR) TKA trial prosthesis was implanted; in the other ten knees (left knees), the posterior cruciate ligament was cut and a posterior substitution (PS) TKA trial prosthesis was implanted. Lamina spreaders were set at 100 N of tension, one on the medial and one on the lateral articular space. Gaps were then measured with a caliper before and after PT sectioning.

RESULTS

the correlation between femoral dimensions and popliteus insertion distance from articular surfaces was measured with the Pearson correlation index and considered significant. In the CR-TKA group, medial and lateral gap measurements showed a significant increase after PT sectioning both in flexion and in extension. In the PS-TKA group, lateral gap measurements showed a significant increase after PT sectioning both in flexion and in extension, while the medial gap measurements increased significantly only in flexion.

CONCLUSIONS

PT sectioning destabilized both the lateral and the medial aspects of the knee. A greater effect was observed in the lateral compartment. The most statistically reliable effect was observed with the knee in flexion. In addition, we observed that preserving the PCL does not prevent lateral gap opening after PT sectioning.

CLINICAL RELEVANCE

PT should always be preserved when performing a TKA, because its resection can affect gap balancing, in flexion and in extension.

TYPE OF STUDY

controlled laboratory study.

Painful knee prosthesis: surgical approach

There are many conditions that may be responsible of a painful knee prosthesis. The possible causes are not always easily diagnosed. Common causes of prosthetic failure, such as aseptic loosening, infection, instability, progressive patellar arthropathy and recurrent synovitis are associated with clearly defined radiographic and/or clinical evidence. Prosthetic infection should always be considered first until any other cause has been demonstrated. In the presence of an infected prosthesis we carry out a two-step revision. Aseptic loosening needs implant revision more often with increasing prosthesis stability. Varus-valgus, anteroposterior, global and patello-femoral instability are failures often due to technical errors; superstabilized or constrained implants are needed depending on the instability entity.In presence of patello-femoral pain it is necessary to evaluate the stability of the patellar component and any alterations in its motion. Patellar progressive arthropathy can often cause late-onset knee pain; in this case patella resurfacing is needed. Altered patellar tracking, may need a lateral release but in some cases is related to misalignment of the components and the revision procedure is mandatory. Nevertheless, the diagnosis and treatment of a painful knee prosthesis can be extremely difficult if there is no clear evidence of any of the most common causes of failure. Referred pain, ligament and tendon dysfunction, cutaneous neuromas, synovitis, a patellar clunk have to be diagnosed and treated.A possible aetiological understimated factor is painful knee prosthesis due to metals sensibilization, in particular to nickel. In this event the quantity of nickel in the revision prosthesis must be minimal.