Richard Carrington

Chromosomal Aberrations in the Peripheral Blood of Patients with Metal-on-Metal Hip Bearings

BACKGROUND Approximately one-third of patients undergoing joint replacement are under sixty years of age. Many of these patients may be exposed to wear debris from the orthopaedic implant for several decades. Clinical follow-up of this group of patients has been short compared with the lifetimes of the patients, and the long-term effects of this chronic exposure are unknown. METHODS By using cytogenetic biomarkers (twenty-four-color fluorescent in situ hybridization [FISH]), we analyzed the peripheral blood leukocytes for chromosomal aberrations in three groups of subjects: (1) six age and sex-matched control subjects who had no implant and did not smoke (control group), (2) five subjects in whom an implant with a metal-on-metal articulation had been in situ for an average of thirty-five years (metal-on-metal group), and (3) four subjects in whom a metal-on-metal implant had been revised to a metal-on-polyethylene articulation at an average of twenty-two years (revised group). RESULTS The number of chromosomal aberrations in the metal-on-metal group was greater than that in the control group. Specifically, the percentage of aneuploidy gain was three times greater (p = 0.01) in the metal-on-metal group. Structural aberrations were not seen in the control group, and this difference was highly significant (p = 0.003). Also, the number of chromosomal aberrations in the metal-on-metal group was greater than that in the revised group. Specifically, the percentage of structural aberrations was thirty-one-fold higher (p = 0.013). The percentage of aneuploidy gain in the metal-on-metal group was about twice that in the revised group, although this difference was not significant (p = 0.37). The percentage of aneuploidy gain in the revised group was about double that in the control group, although this difference was also not significant (p = 0.41). Translocations were seen only in subjects with a metal-on-metal articulation. CONCLUSIONS The clinical consequences of the chromosomal changes seen in this study are unknown, and it is unknown if the changes are present in other cells in the body. The results emphasize the need for additional investigations into the effect of chronic exposure to elevated levels of metal ions produced by orthopaedic implants.

Autologous chondrocyte implantation in the knee: mid-term to long-term results.

BACKGROUND From 1998 to 2008, 1000 skeletally mature patients underwent autologous chondrocyte implantation for an osteochondral defect of the knee. We evaluated the functional outcomes in 827 of 869 patients who had undergone autologous chondrocyte implantation with Chondron or periosteum (ACI-C/ACI-P) or matrix-assisted chondrocyte implantation (MACI) and attempted to identify factors that influenced outcome. METHODS The age of the patient, the size and site of the osteochondral lesion, previous surgery, and the presence of early osteoarthritis were assessed for their influence on outcomes. Each factor was evaluated in a separate Cox proportional hazards model with use of hazard ratios (HRs), with 95% confidence intervals (CIs), describing the likelihood of failure for that particular factor. Outcomes were assessed with use of the modified Cincinnati score, visual analog scale pain score, and Stanmore functional score. RESULTS The mean duration of follow-up was 6.2 years (range, two to twelve years). The mean age was thirty-four years (range, fourteen to fifty-six years), with 493 males and 334 females. The average size of the defect was 409 mm2 (range, 64 to 2075 mm2). Four hundred and twenty-one procedures (51%) were performed on the medial femoral condyle; 109 (13%), on the lateral femoral condyle; 200 (24%), on the patella; and fifty (6%), on the trochlea. Kaplan-Meier survival analysis revealed that the unadjusted graft survival rate was 78.2% at five years and 50.7% and ten years for the entire cohort. No difference was found between the survival rates of the ACI-C/ACI-P and MACI techniques (HR = 0.948, 95% CI = 0.738 to 1.219, p = 0.678). There was a significant postoperative improvement in the function and pain scores of all three outcome measures (p < 0.002). Survivorship in the group with a previous cartilage regenerative procedure was inferior to that in patients with a previously untreated lesion, with failure five times more likely in the former group (HR = 4.718, standard error [SE] = 0.742, 95% CI = 3.466 to 6.420, p < 0.001). Degenerative change in any compartment had a significant detrimental effect on survivorship, with survivorship worsening as the osteoarthritis grade increased (Grade 1: HR = 2.077, 95% CI = 1.299 to 3.322, p = 0.002; Grade 2: HR = 3.450, 95% CI = 2.646 to 4.498, p < 0.001; and Grade 3: HR = 3.820, 95% CI = 2.185 to 6.677, p < 0.001). CONCLUSIONS Our study demonstrated an overall graft survival of 78% at five years and 51% beyond ten years following both autologous chondrocyte implantation techniques. Despite study limitations, our results demonstrate that autologous chondrocyte implantation for the treatment of osteochondral defects of the knee can achieve good results. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tibial plateau stress fracture: a complication of unicompartmental knee arthroplasty using 4 guide pinholes.

Unicompartmental knee arthroplasty has gained popularity recently as a treatment for unicompartmental tibiofemoral non inflammatory arthritis. Tibial plateau stress fracture after unicompartmental knee arthroplasty (UKA) through guide pin holes placed in the proximal tibia has not been previously reported. In each case in this report, the compressive strength of the proximal tibia was reduced by the drilling of multiple holes for the placement of guide pins and holes for the lugs of the tibia component resulting in fracture through these holes between 3 and 18 weeks (median 8 weeks) post-operatively. In at least one case, the medial tibial cortex was violated by one pin. All cases required revision total knee arthroplasty (TKA). It is intuitive to caution against the use of multiple guide holes in the proximal tibia in UKA. If 3 or more hole pins are deemed necessary, surgeons must be aware of the potential for stress fracture and monitor patients accordingly. Peripheral pins that infract the medial tibial cortex should also be avoided.

Long-term Results of Autologous Chondrocyte Implantation in the Knee for Chronic Chondral and Osteochondral Defects

Background: Autologous chondrocyte implantation (ACI) has been shown to be effective in the midterm for the treatment of symptomatic articular cartilage lesions of the knee, but few long-term series have been published. The multioperated chronic articular cartilage defect remains a difficult condition to treat. Purpose: To examine the long-term clinical results of ACI for large chronic articular cartilage defects, many treated as salvage. Study Design: Case series; Level of evidence, 4. Methods: This is a prospective case series of 104 patients with a mean age of 30.2 years and a symptomatic lesion of the articular cartilage in the knee, who underwent ACI between 1998 and 2001. The mean duration of symptoms before surgery was 7.8 years. The mean number of previous surgical procedures on the cartilage defect, excluding arthroscopic debridement, was 1.3. The defects were large, with a mean size of 477.1 mm2 (range, 120-2500 mm2). The modified Cincinnati, Stanmore/Bentley, and visual analog scale for pain scoring systems were used to assess pain and functional outcomes at a minimum 10 years (mean, 10.4 years; range, 10-12 years). Results: Twenty-seven patients (26%) experienced graft failure at a mean of 5.7 years after ACI. Of the 73 patients who did not fail, 46 patients (63% of patients with a surviving graft) had an excellent result, 18 (25%) were good, 6 (8%) were fair, and 3 (4%) had a poor result. Of a total of 100 patients successfully followed up, 98 were satisfied with the ACI technique for their chronic knee pain and would undergo the procedure again. Conclusion: Autologous chondrocyte implantation can provide a long-term solution in more than 70% of young patients of a difficult-to-treat group with large chronic articular cartilage lesions, even in the salvage situation.

McKeever Hemiarthroplasty of the Knee in Patients Less Than Sixty Years Old

BACKGROUND Knee arthritis in the young patient is a challenging problem that may necessitate surgical treatment. We continue to perform hemiarthroplasty with a metallic tibial implant in selected young patients who, for various reasons, are not candidates for osteotomy, unicompartmental arthroplasty, or total knee arthroplasty. The purpose of the present study was to determine the minimum twelve-year results of this procedure in young patients. METHODS The original study group consisted of a consecutive series of twenty-four patients (twenty-six knees) who were managed with McKeever tibial hemiarthroplasty for the treatment of unicompartmental osteoarthritis of the knee. All patients were younger than sixty years of age at the time of the index procedure (average age, 44.6 years). During the study period, two patients died and one was lost to follow-up, leaving twenty-one patients (twenty-three knees) available for review. All patients were followed clinically for a minimum of twelve years or until revision. Knee Society knee and functional scores and Tegner scores were determined, and seven of the ten implants were evaluated radiographically. RESULTS Thirteen knees were revised at an average of eight years after the index procedures. All thirteen knees had an uncomplicated revision to either a unicompartmental arthroplasty or total knee arthroplasty. Ten retained implants were available for clinical review after an average duration of follow-up of 16.8 years. The mean Knee Society knee scores, functional scores, and Tegner scores, available for nine of these ten knees, were 80, 97, and 4.2, respectively. CONCLUSIONS We believe that the McKeever tibial hemiarthroplasty continues to be a reasonable surgical option for patients who are not candidates for osteotomy and are too young or too active for a unicompartmental or total knee arthroplasty.

Autologous Chondrocyte Implantation in the Adolescent Knee

Background Autologous chondrocyte implantation (ACI) has been shown to have favorable results in the treatment of symptomatic chondral and osteochondral lesions. However, there are few reports on the outcomes of this technique in adolescents. Purpose The aim of this study was to assess pain relief and functional outcome in adolescents undergoing ACI. Study Design Case series; Level of evidence, 4. Methods Thirty-five adolescent patients undergoing ACI or matrix-assisted chondrocyte implantation (MACI) were identified from a larger cohort. Four patients were lost to follow-up, leaving 31 patients (24 ACI, 7 MACI). The mean age was 16.3 years (range, 14-18 years) with a mean follow-up of 66.3 months (range, 12-126 months). There were 22 male and 9 female patients. All patients were symptomatic; 30 had isolated lesions and 1 had multiple lesions. Patients were assessed preoperatively and post-operatively using the visual analog scale (VAS) score for pain, the Bentley Functional Rating Score, and the Modified Cincinnati Rating System. At 1 year postoperatively, patients were recalled for a diagnostic biopsy, which was successfully attained in 21 patients. Results The mean pain scores improved from 5 preoperatively to 1 postoperatively. The Bentley Functional Rating Score improved from 3 to 0, while the Modified Cincinnati Rating System improved from 48 preoperatively to 92 postoperatively with 84% of patients achieving excellent or good results. All postoperative scores exhibited significant improvement from preoperative scores. One patient underwent graft hypertrophy and 1 patients graft failed and was revised. Biopsy results revealed hyaline cartilage in 24% of cases, mixed fibro/hyaline cartilage in 19%, and fibrocartilage in 57%. Conclusion Results show that, in this particular group who received ACI, patients experienced a reduction in pain and significant improvement in postoperative function after ACI or MACI. The authors believe that ACI is appropriate in the management of carefully selected adolescents with symptomatic chondral and osteochondral defects.

Outcomes of infected revision knee arthroplasty managed by two-stage revision in a tertiary referral centre.

BACKGROUND A two-stage revision remains the gold standard to eradicate deep infection in total knee arthroplasty. Higher failure rates are associated with a number of factors including poly-microbial infections, multiresistant organisms and previous operations. The aims are to investigate [1] the overall success rate of a two-stage revision for infections in TKA, [2] the outcome of repeat two-stage revisions in recurrent infections and [3] the factors affecting the outcomes of such cases. METHODS We present the outcomes of a consecutive, retrospective case series of 51 periprosthetic joint infections managed with a two-stage revision knee arthroplasty over a three year period. RESULTS Forty-six (90%) of 51 were referred from other hospitals. Infection was successfully eradicated in 24 (65%) of 37 patients undergoing an initial two-stage procedure. Following a failed two-stage revision, a repeat two-stage revision was performed in 19 patients eradicating infection in 8 (42%). A third two-stage was performed in five of these patients eradicating infection in three with an average follow-up of 43 months. Multidrug resistance was present in 69%, and 47% of the patients were infected with multiple organisms. All unsuccessful outcomes involved at least one multidrug-resistant organism compared to 43% in the successful cohort (P=0.0002). Serological markers prior to a second-stage procedure were not significantly different between successful and unsuccessful outcome groups. CONCLUSION Single or multiple two-stage revisions can eradicate infection despite previous failed attempts. In this series, failure is associated with multidrug resistance, previous failed attempts to eradicate infection and a less favourable host response.

A new approach to managing patients with problematic metal hip implants: the use of an Internet-enhanced multidisciplinary team meeting: AAOS exhibit selection.

BACKGROUND Over one million patients worldwide are estimated to have a metal-on-metal hip arthroplasty. To improve the management of these patients and reduce surgeon uncertainty regarding decision-making, we designed an Internet-enhanced multidisciplinary team (iMDT) working approach. METHODS From August 2012 to April 2014, the iMDT discussed 215 patients with 266 metal-on-metal hip arthroplasties. Of these, 236 primary arthroplasties (132 hip resurfacing and 104 total hip) were analyzed. The remaining thirty cases involved problematic revised hips and were therefore excluded. The possible recommendations of the iMDT were monitoring, further investigation, or surgery. The concordance between the recommendation and the actual management was used to assess the usefulness of this approach in reducing uncertainty in surgeon-level decision-making. RESULTS The median Oxford Hip Score was 35 (range, 4 to 48), and median cobalt and chromium levels in whole blood were 3.54 ppb (range, 0.18 to 161.46 ppb) and 3.17 ppb (range, 0.20 to 100.67 ppb), respectively. Magnetic resonance imaging revealed abductor muscle atrophy in ninety-two (39%) of the hips and a pseudotumor in eighty (34%). The iMDT recommended monitoring of 146 (61.9%) of the hips, further investigation of thirty (12.7%), and surgery in sixty (25.4%). The actual outcome was concordant with the recommendation in 211 (91.7%) of the hips. CONCLUSIONS Our iMDT approach to the metal-on-metal hip burden combines the tacit knowledge of an expert panel, regulatory guidance, and up-to-date evidence to improve decision-making among surgeons. The high level of concordance between the recommendation and the actual outcome, combined with the feasibility of the methods used, suggest that this method effectively reduces uncertainty among surgeons and may lead to improved patient outcomes.This article was updated on March 27, 2015, because of a previous error. In Table IV, the heading that had previously read “High risk” now reads “Low risk” and vice versa. An erratum has been published: J Bone Joint Surg Am. 2015;97(9):e42. Background: Over one million patients worldwide are estimated to have a metal-on-metal hip arthroplasty. To improve the management of these patients and reduce surgeon uncertainty regarding decision-making, we designed an Internet-enhanced multidisciplinary team (iMDT) working approach. Methods: From August 2012 to April 2014, the iMDT discussed 215 patients with 266 metal-on-metal hip arthroplasties. Of these, 236 primary arthroplasties (132 hip resurfacing and 104 total hip) were analyzed. The remaining thirty cases involved problematic revised hips and were therefore excluded. The possible recommendations of the iMDT were monitoring, further investigation, or surgery. The concordance between the recommendation and the actual management was used to assess the usefulness of this approach in reducing uncertainty in surgeon-level decision-making. Results: The median Oxford Hip Score was 35 (range, 4 to 48), and median cobalt and chromium levels in whole blood were 3.54 ppb (range, 0.18 to 161.46 ppb) and 3.17 ppb (range, 0.20 to 100.67 ppb), respectively. Magnetic resonance imaging revealed abductor muscle atrophy in ninety-two (39%) of the hips and a pseudotumor in eighty (34%). The iMDT recommended monitoring of 146 (61.9%) of the hips, further investigation of thirty (12.7%), and surgery in sixty (25.4%). The actual outcome was concordant with the recommendation in 211 (91.7%) of the hips. Conclusions: Our iMDT approach to the metal-on-metal hip burden combines the tacit knowledge of an expert panel, regulatory guidance, and up-to-date evidence to improve decision-making among surgeons. The high level of concordance between the recommendation and the actual outcome, combined with the feasibility of the methods used, suggest that this method effectively reduces uncertainty among surgeons and may lead to improved patient outcomes.

Treating articular cartilage injuries of the knee in young people

#### Summary points Articular chondral and osteochondral injuries of the knee are common in people aged under 35 years, and symptomatic lesions left untreated may lead to chronic pain and disability. Patients with articular chondral injuries often have a poorer function score than those awaiting surgery for other knee disorders, such as osteoarthritis or a ruptured anterior cruciate ligament.1 Patients with articular cartilage injuries may go on to develop early onset osteoarthritis with long term morbidity and consequent high use of health service resources; successful early treatment of these lesions would probably be cost effective. Chondral and osteochondral lesions may not be diagnosed or may present late because patients will often give a history of an apparent insignificant trauma and doctors may fail to understand the importance of an effusion in the knee joint, which always indicates joint disease.2 Radiographs of the knee may be poorly interpreted. This review discusses the diagnosis and management (conservative and surgical) of injuries to the articular cartilage of the knee and draws on published research articles and the authors’ own experience. We searched the Cochrane database, PubMed, and Google Scholar up to December 2009. We analysed randomised controlled trials and comparison trials, as well as articles on operative technique and case series. Long bone articular surfaces are covered with hyaline cartilage. Damage to this hyaline cartilage is known as a chondral injury or, if the underlying bone is also fractured, an osteochondral injury. Articular cartilage is avascular and aneural, so pain would not be expected. Yet some patients with chondral lesions do present with …

In vivo roughening of retrieved total knee arthroplasty femoral components

BACKGROUND Joint registry data highlights the higher rates of cumulative revision for younger patients undergoing TKR. One of the reasons associated with this higher revision rate may be due to the wear of the UHMWPE leading to loosening. Alternate bearing surfaces have been developed to address this problem; however, roughening of the metal bearing surface has not been demonstrated in vivo. METHOD We recorded roughness measurements of retrieved femoral components. RESULTS Average lateral condyle roughness was 0.032 μm, compared to control values of 0.020 μm, p=0.002; average medial condyle roughness was 0.028 μm, compared to a control value of 0.019, p<0.001. CONCLUSION There was a small but statistically significant roughening of femoral components in vivo compared to controls. This may have important implications for aseptic loosening of knee arthroplasty components and the decision to use scratch resistant components.