The unsuspected prosthetic joint infection : incidence and consequences of positive intra-operative cultures in presumed aseptic knee and hip revisions.

AIMS: Positive cultures are not uncommon in cases of revision total knee and hip arthroplasty (TKA and THA) for presumed aseptic causes. The purpose of this study was to assess the incidence of positive intra-operative cultures in presumed aseptic revision of TKA and THA, and to determine whether the presence of intra-operative positive cultures results in inferior survival in such cases. PATIENTS AND METHODS: A retrospective cohort study was assembled with 679 patients undergoing revision knee (340 cases) or hip arthroplasty (339 cases) for presumed aseptic causes. For all patients three or more separate intra-operative cultures were obtained. Patients were diagnosed with a previously unsuspected prosthetic joint infection (PJI) if two or more cultures were positive with the same organism. Records were reviewed for demographic details, pre-operative laboratory results and culture results. The primary outcome measure was infection-free implant survival at two years. RESULTS: The incidence of unsuspected PJI was 27 out of 340 (7.9%) in TKA and 41 out of 339 (12.1%) in THA. Following revision TKA, the rate of infection-free implant survival in patients with an unsuspected PJI was 88% (95% confidence intervals (CI) 60 to 97) at two years compared with 98% (95% CI 94 to 99) in patients without PJI (p = 0.001). After THA, the rate of survival was similar in those with unsuspected PJI (92% (95% CI 73 to 98) at two years) and those without (94% (95% CI 89 to 97), p = 0.31). CONCLUSION: Following revision of TKA and THA for aseptic diagnoses, around 10% of cases were found to have positive cultures. In the knee, such cases had inferior infection-free survival at two years compared with those with negative cultures; there was no difference between the groups following THA. Cite this article: Bone Joint J 2017;99-B:1482-9.

No Difference in Implant Micromotion Between Hybrid Fixation and Fully Cemented Revision Total Knee Arthroplasty: A Randomized Controlled Trial with Radiostereometric Analysis of Patients with Mild-to-Moderate Bone Loss.

BACKGROUND: In revision total knee arthroplasty (TKA), the femoral component and tibial baseplate are usually cemented. However, stems can be fixed either with cement or with a press-fit technique, with the latter resulting in hybrid fixation. There is no consensus on the preferred stem fixation technique. Therefore, we compared the stability of cemented TKA implants with the stability of TKA implants fixed with the hybrid technique in a prospective randomized trial using radiostereometric analysis (RSA). METHODS: Thirty-two patients with a Type-I or II bone defect who needed revision TKA and were randomly allocated at the time of surgery into either the cemented or hybrid-fixation group were included in the study. The radiographs for the RSA were obtained during hospitalization (baseline); at 6 weeks; and at 3, 6, 12, and 24 months. Migration of the femoral and tibial implants was measured using model-based RSA and expressed along or around the 3 orthogonal axes and as total translation (TT) and total rotation (TR). Clinical results were evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), active flexion, and visual analog scale (VAS) scores for pain and satisfaction. Mann-Whitney and chi-square tests were used to compare migration and clinical outcomes between the cement and hybrid techniques. RESULTS: At 24 months, no difference in median migration or the number of migrating components was found between the cemented and hybrid-fixation groups. In each group, approximately one-third of the tibial components had total rotation of >1°. The clinical scores did not differ between the techniques. CONCLUSIONS: At 24 months after revision TKAs, cemented and hybrid-fixation replacements were equally stable. Unexpectedly, both groups had implants with >1 mm or >1° of micromotion although there were no clinical or radiographic signs of loosening. Whether these findings indicate the possibility of loosening with longer follow-up remains to be investigated. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Moderate clinical improvement after revision arthroplasty of the severely stiff knee.

PURPOSE: Revision of the severe stiff total knee arthroplasty (TKA) is challenging, and clinical outcome is inferior to other indications for revision. The purpose of the present study was to determine clinical outcome of TKA revision in patients with severe stiffness (range of motion (ROM) ≤ 70°) and evaluate a possible influence of accompanying findings, such as component malposition, aseptic loosening or instability. METHODS: A prospective cohort of 40 patients with a preoperative ROM ≤ 70° and a minimum of 2-year follow-up after total system revision (Genesis or Legion stemmed condylar implant) was evaluated. ROM, Knee Society Scoring System (KSS) and visual analogue scale (VAS) pain scores were obtained preoperatively and at 2 years. Patient satisfaction and complication rate were assessed. Component malposition was most frequently reported as accompanying finding (n = 27). Comparisons between pre- and postoperative outcome (p < 0.05) and between different subgroups (component malposition, aseptic loosening, and instability) based on accompanying findings were made (no statistical comparison). RESULTS: ROM, KSS and VAS pain scores improved significantly (p < 0.001): median ROM at two years 85° (range 10-125) and median gain 25° (range -10 to +85). Median VAS satisfaction was 53.5 points (range 15-98). Seventeen patients reported at least one complication, including one re-revision. Six patients underwent manipulation under anaesthesia, and five were referred to the pain clinic. No clear differences between subgroups were observed. CONCLUSIONS: TKA revision in patients with severe stiffness resulted in a moderate but significant improved clinical outcome after 2 years. Accompanying abnormalities such as component malposition, aseptic loosening or instability did not influence clinical outcome. Realistic patient counselling on the moderate outcome and possible remaining limitations in daily life might help to improve patient satisfaction. LEVEL OF EVIDENCE: Therapeutic studies-case series with no comparison group, Level IV.

The accuracy of positioning of a custom-made implant within a large acetabular defect at revision arthroplasty of the hip.

We evaluated the accuracy with which a custom-made acetabular component could be positioned at revision arthroplasty of the hip in patients with a Paprosky type 3 acetabular defect. A total of 16 patients with a Paprosky type 3 defect underwent revision surgery using a custom-made trabecular titanium implant. There were four men and 12 women with a median age of 67 years (48 to 79). The planned inclination (INCL), anteversion (AV), rotation and centre of rotation (COR) of the implant were compared with the post-operative position using CT scans. A total of seven implants were malpositioned in one or more parameters: one with respect to INCL, three with respect to AV, four with respect to rotation and five with respect to the COR. To the best of our knowledge, this is the first study in which CT data acquired for the pre-operative planning of a custom-made revision acetabular implant have been compared with CT data on the post-operative position. The results are encouraging.

Survivorship of the cementless Spotorno femoral component in patients under 50 years of age at a mean follow-up of 18.4 years.

The long-term survival of the cementless Spotorno CLS femoral component in patients aged > 50 years at the time of arthroplasty was investigated. Survivorship analysis of a consecutive series of 85 patients (100 hips; under 50 years of age at a mean follow-up of 18.4 years (16.3 to 20.8)) was performed. The clinical and radiographic outcomes were satisfactory. The overall rate of survival of the femoral component was 93.5% (95% confidence interval (CI), 90.9 to 96.1) after 19 years. Survival with revision for aseptic loosening as the end point was 95.7% (95% CI 93.6 to 97.8%) at 19 years. This study demonstrates an excellent long-term survival of the Spotorno CLS femoral component after 16 to 20 years in young patients undergoing total hip arthroplasty.

Dual mobility acetabular component in revision total hip arthroplasty for persistent dislocation: no dislocations in 50 hips after 1-5 years.

BACKGROUND: A dual mobility cup has the theoretic potential to improve stability in primary total hip arthroplasty (THA) and mid-term cohort results are favorable. We hypothesized that use of a new-generation dual mobility cup in revision arthroplasty prevents dislocation in patients with a history of recurrent dislocation of the THA. MATERIALS AND METHODS: We performed a retrospective cohort study of patients receiving an isolated acetabular revision with a dual mobility cup for recurrent dislocation of the prosthesis with a minimum follow-up of 1 year. Kaplan-Meier survival analyses were performed with dislocation as a primary endpoint and re-revision for any reason as a secondary endpoint. RESULTS: Forty-nine consecutive patients (50 hips) were included; none of the patients was lost to follow-up. The median follow-up was 29 months (range 12-66 months). Two patients died from unrelated causes. Survival after 56 months was 100 % based on dislocation and 93 % (95 % CI 79-98 %) based on re-revision for any reason. Radiologic analysis revealed no osteolysis or radiolucent lines around the acetabular component during the follow-up period. CONCLUSION: The dual mobility cup is an efficient solution for instability of THA with a favorable implant survival at 56 months. LEVEL OF EVIDENCE: Level 4, retrospective case series.

Bicruciate substituting design does not improve maximal flexion in total knee arthroplasty: a randomized controlled trial.

BACKGROUND: An important factor in the functional results after total knee arthroplasty is the achieved maximal flexion. The main purpose of this study was to compare the maximal knee flexion one year after surgery in patients who received either the bicruciate substituting knee system or the conventional posterior stabilized system. METHODS: In a prospective randomized controlled trial, 124 patients presenting with osteoarthritis received the bicruciate substituting or the conventional posterior stabilized prosthesis. The primary outcome was the maximum flexion angle at one year postoperatively on a lateral radiograph made with the supine patient using manual force to bend the knee. Secondary outcomes were active flexion (lying and standing), the Knee Society Score, the Patella Scoring System score, the University of California Los Angeles score, the number and type of adverse device effects, and visual analog scale satisfaction up to two years postoperatively. The outcome measures of both groups were compared using one-sided t tests and non-parametric alternatives, with a significance level of p < 0.05. RESULTS: No significant differences between the two groups were observed in maximal flexion on radiographs and in active flexion at baseline. The median maximal flexion on radiographs was 127° (range, 83° to 150°) for the bicruciate substituting group and 125° (range, 74° to 145°) for the conventional posterior stabilized group. The two groups showed comparable two-year results with respect to the Knee Society Score, the Patella Scoring System, the University of California Los Angeles score, and visual analog scale satisfaction. In the bicruciate substituting group, forty-one adverse device effects in twenty-six patients were reported, including three total system revisions and fourteen manipulations under anesthesia, compared with the conventional posterior stabilized group, in which sixteen adverse device effects were observed in thirteen patients, including six manipulations under anesthesia (p = 0.012). CONCLUSIONS: Patients who receive a bicruciate substituting system compared with those who receive a conventional posterior stabilized system have comparable knee flexion characteristics and clinical and functional outcomes but more complications by two years after total knee arthroplasty. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Reactivation of ancient joint tuberculosis of the knee following total knee arthroplasty after 61 years: a case report.

The prevalence of pulmonary tuberculosis is increasing and is associated with a rise in skeletal tuberculosis. Even after appropriate anti-tuberculosis therapy, reactivation of the infection may occur, even after many years. In this case report we describe a patient who had a reactivation of tuberculosis in the knee after total knee arthroplasty. At the age of 14 years, the patient had isolated tuberculosis arthritis of the left knee. Reactivation occurred after total knee arthroplasty 61 years later, at the age of 75. The patient was treated with a combined therapy; first the joint was irrigated with povidine-iodine and saline solution, and gentamicin beads were left behind. When the cultures revealed Mycobacterium tuberculosis, drug therapy of isoniazid, rifampicin, ethambutol and pyrazinamide was started and was continued for 9 months postoperatively. At a recent follow-up, the patient is doing well, with good range of motion in the knee.

High-flexion, motion-guided total knee arthroplasty: who benefits the most?

A multicenter study was performed to determine which patients have the most potential to benefit from total knee arthroplasty (TKA) with a high-flexion, guided-motion design. In 201 consecutive TKAs, the mean gain in range of motion (ROM) was 14 degrees at 3 months and 24 degrees at 6 months. The gain in flexion was significant at 3 and 6 months postoperatively. No differences were found based on preoperative diagnosis, age, or sex. There was a poor correlation between body mass index and ROM. Pre- and postoperative flexion also displayed a weak correlation. Patients with the least preoperative flexion (<90 degrees) gained the most degrees of flexion (26 degrees). We conclude that the use of a high-flexion, guided-motion TKA allows a significant functional improvement in patients with preoperative stiffness and the preservation of good flexion in patients with normal preoperative flexion.

The anterior-posterior laxity after total knee arthroplasty inserted with a ligament tensor.

Goal of this study is to determine the anterior-posterior laxity in 30 degrees of knee flexion for a posterior cruciate retaining total knee arthroplasty with a relative dished insert and implanted with a ligament tensor. Furthermore, the correlation between these AP laxities and the postoperative range of motion (ROM) and postoperative Knee Society Score (KSS) is analysed. Fifty-one balanSys total knee arthroplasties were performed in 49 patients between 1998 and 2000. These arthroplasties are analysed with respect to AP laxity (Rolimeter), ROM and KSS with a mean follow-up of 4.6 years. The mean anterior laxity is 2.8 mm with no posterior laxities at all. The average postoperative ROM is 110 degrees with an average KSS of 142. No correlations between AP-laxity and postoperative ROM or between AP-laxity and postoperative KSS are found. A posterior cruciate retaining TKA with a relative dished insert and implanted with a tensor is very stable in the anterior-posterior direction in 30 degrees of knee flexion. This limited laxity does not seem to disadvantage the mean postoperative ROM and KSS, when compared to other TKA studies.

Step-cut tibial tubercle osteotomy for access in revision total knee replacement.

In this retrospective cohort, the results of step-cut tibial tubercle osteotomy (TTO) in 39 revision total knee arthroplasty, using the Continuum Knee System (CKS), are determined. In 39 revision, total knee arthroplasties, adequate exposure was obtained after step-cut TTO. All knees were recently reviewed for clinical and radiological results. Symptomatic TTO-related complications occurred in three out of 39 patients. Two patients had proximal migration of the tibial tubercle due to an insufficient step-cut. Another patient had posttraumatic avulsion of the tibial tubercle. No TTO-related extensor lag or tibial fracture occurred We conclude that, when adequate exposure cannot be obtained, step-cut TTO is a safe and reproducible procedure if strict attention is paid to technique and fixation. It does not compromise the functional results of TKA.

Triple osteotomy of the pelvis for acetabular dysplasia: results at a mean follow-up of 15 years.

We report the long-term results of 51 pelvic osteotomies in 43 patients with a mean follow-up of 15 years (13 to 20). The mean age of the patients was 28 years (14 to 46). At review three patients were lost to follow-up, and six had received a total hip arthroplasty. Of 48 hips, 42 (88%) were preserved, with good to excellent clinical results in 27 (64%). Pre-operatively, 41 (80%) of the treated hips had shown no sign of osteoarthritis. Thirty-one (65%) hips showed no progression of osteoarthritis after follow-up for 15 years. Significant negative factors for good long-term results were the presence of osteoarthritic changes and a fair or poor clinical score pre-operatively. Pelvic reorientation osteotomy for symptomatic hip dysplasia can give satisfactory and reproducible long-term clinical results.

Treatment of postoperative bleeding after fondaparinux with rFVIIa and tranexamic acid.

Treatment of a haemorrhagic shock after just a single dose of fondaparinux in an orthopaedic patient with reduced renal clearance is presented. Since all routine haemostatic parameters were nearly normal, single doses of rFVIIa (90 microg/kg) and of tranexamic acid (15 mg/kg) were administered to improve thrombin generation and reduce fibrinolysis. This case is the first showing the effectiveness of combining single doses of rFVIIa and tranexamic acid in controlling severe postoperative bleeding after fondaparinux.

Computer-assisted pelvic surgery: an in vitro study of two registration protocols.

An in vitro study was done to test the accuracy and functionality of computer-assisted surgery in pelvic orthopaedic surgery. The study was done on two fresh hips from one cadaver. In each hip, 10 titanium marker screws were inserted through standard pelvic osteotomy incisions. After a computed tomography scan was obtained the data were introduced into the navigation system. For the accuracy measurements the location of the center of the spherical heads of the marker screws was determined relative to a reference base attached to the pelvis using a special pointer that corresponded to the spherical head of the screws. A randomized trial was done with two surgeons to test the accuracy of two different anatomy-based registration protocols. The deviation between the virtual position of the marker screws in the pelvis, calculated by the computer after each anatomy based registration, and the real position were compared for each registration. Accuracy is not only related to the distance of the computed tomography slices and the necessary computed tomography field of view but also depends on the location of the point on the pelvis.