Knee salvage in revision arthroplasty after massive bone loss of the femur condyles (≥Engh III) with a single-modular-hinged knee revision implant

Spacer exchange in persistent periprosthetic joint infection: microbiological evaluation and survivorship analysis

PURPOSE

The purposes of this study were to determine demographics and characteristics of patients who underwent spacer exchange for persistent infection in the setting of two-stage arthroplasty for periprosthetic joint infection, to describe the microbiology of pathogens involved, to analyze survivorship free from infection in these patients.

METHODS

The institutional prospectively collected database was reviewed to enroll patients with minimum 2 years follow-up. Patients who underwent two-stage procedure for septic arthritis were excluded, as were patients who had spacer fracture or dislocation.

RESULTS

A total of 34 patients (41 procedures) were included. Mean age was 65.0 ± 12.8 years. Mean follow-up was 53.4 ± 24.8 months. Mean number of previous procedures was 3.6 ± 1.2. A total of 27 (79.4%) patients underwent final reimplantation. The most frequently isolated pathogen in spacer exchange was Staphylococcus epidermidis (10 cases, 28.6%). Polymicrobial cultures were obtained from 9 (25.71%) patients, 10 (28.6%) presented culture-negative infections. A total of 11 (32.4%) resistant pathogens were isolated, and 16 (47.0%) difficult to treat pathogens were detected. Eradication rate was 78.8%. Overall survivorship of implants after final reimplantation was 72.8% at 51.8 months.

CONCLUSION

Surgeons should be aware that subjects necessitating spacer exchange often present multiple comorbidities, previous staged revision failures, soft-tissue impairment and difficult to treat infection. In these patients, spacer exchange provides good clinical results and infection eradication, preventing arthrodesis or amputation.

Complications and failures of non-tumoral hinged total knee arthroplasty in primary and aseptic revision surgery: A review of 290 cases

INTRODUCTION

Hinged total knee arthroplasty (TKA) implants are a commonly used option during revision or even primary surgery, but their complications are not as well known, due to the rapid adoption of gliding implants. The literature is inconsistent on this topic, with studies having a small sample size, varied follow-up duration and very different indications. This led us to carry out a large multicentre study with a minimum follow-up of 5 years to evaluate the complications after hinged TKA in a non-tumoral context based on the indications of primary arthroplasty, aseptic surgical revision or fracture treatment around the knee.

HYPOTHESIS

Hinged TKA was associated with a high complication rate, no matter the indication.

MATERIAL AND METHODS

Two hundred and ninety patients (290 knees) were included retrospectively between January 2006 and December 2011 at 17 sites, with a minimum follow-up of 5 years. The patients were separated into three groups: primary surgery (111 patients), aseptic revision surgery (127 patients) and surgery following a recent (<3 months) fracture (52 patients: 13 around the TKA and 39 around the knee treated by hinged TKA). Patients who had an active infection the knee of interest were excluded. All the patients were reviewed based on a standardised computer questionnaire validated by the SOFCOT.

RESULTS

The mean follow-up was 71±39 months [range, 0 to 188]. Of the 290 patients included in the study, 108 patients (37%) suffered at least one complication and 55 patients (19%) had to undergo revision surgery: 16 in the primary TKA group (16/111, 14% of primary TKA), 28 in the revision surgery group (28/127, 22% of revision TKA) and 11 in the fracture treatment group (11/52, 21% of fracture TKA). The complications due to the hinged TKA for the entire cohort from most to least common were stiffness (41/290, 14%), chronic postoperative pain (37/290, 13%), infection (32/290, 11%), aseptic loosening (23/290, 8%), general complications (20/290, 7%), extensor mechanism complications (19/290, 6%), periprosthetic fracture (9/290, 3%), mechanical failure (2/290, 0.7%). In the primary TKA group, the main complication leading to re-operation was infection (12/111, 11%), while it was loosening for the revision TKA group (15/127, 12%) and infection (8/52, 15%) for the fracture TKA group.

DISCUSSION

The 37% complication rate for hinged TKA implants is high, with 19% of them requiring re-operation. The frequency of complications differed depending on the context in which the hinged implant was used (primary, revision, fracture). The complications requiring revision surgery were major ones that prevented patients from preserving their autonomy (infection, symptomatic loosening, fracture, implant failure). The most found complications - stiffness and chronic pain - rarely led to revision.

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Are Serum Metal Ion Levels a Concern at Mid-term Followup of Revision Knee Arthroplasty With a Metal-on-metal Hinge Design?

BACKGROUND

Elevated serum levels of chromium and cobalt ions in metal-on-metal (MoM) bearing surfaces is a well-known phenomenon in THA. However, few studies have addressed this issue in complex primary and revision knee arthroplasty using a MoM hinged mechanism, and no study, to our knowledge, has investigated knees with MoM hinges in patients without megaprostheses (tumor prostheses).

QUESTIONS/PURPOSES

We analyzed a series of patients who received MoM hinged revision knee prostheses and asked: (1) What are the serum metal ion levels at short-term followup? (2) Is there any correlation between metal ion levels and the Knee Society Score (KSS) at this followup?

METHODS

Between 2013 and 2017, we performed 198 revision knee arthroplasties, of which 32 (17.7%) were performed with a latest-generation MoM hinge knee design. In addition, three complex primary TKAs utilizing the same design were included in this study. The device features a metal-on-polyethylene bearing with a MoM hinge. During that period, our general indications for using a hinge were single-stage and two-stage revision surgeries, revisions with large bone defects, and primary TKA with > 20° mechanical malalignment or collateral ligament insufficiency. Of the 35 patients who received this device, 23 patients (65% of the overall group who received this implant; 11 males, 12 females) were available for followup at a median of 28 months (range, 13-61 months), and the remaining 12 (35%) patients were lost to followup. Our rationale for reporting before the more typical 2-year minimum was the finding of elevated serum ion levels with unclear clinical significance. Median age at the time of surgery was 68 years (range, 52-84 years). None of the patients included in the study had other implants with MoM bearings. Serum ion levels of chromium (III) and cobalt were assessed using mass spectrometry. Ion levels > 5 ppb were considered elevated. Clinical outcome was assessed using the original KSS.

RESULTS

Median chromium serum level was 6.3 ppb (range, 0.6-31.9 ppb) and median cobalt serum level was 10.5 (range, 1.0-47.5 ppb). Of the 23 patients, 16 had elevated serum ion levels. There was a moderate correlation between KSS and both chromium (p = 0.029, r = 0.445) and cobalt (p = 0.012, r = 0.502) levels.

CONCLUSIONS

Elevated metal ion levels and radiolucent lines are common after surgery with this MoM hinge design at short-term followup, and we believe this finding is of great concern. Although no patient has yet been revised, these patients will be closely monitored. We recommend that serum ion analysis become a routine part of followup after any hinge TKA in an attempt to better understand the potential consequences of this phenomenon.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

The survivorship of the link endo-rotational hinge total knee arthroplasty: 5-12-year follow-up of 100 patients

INTRODUCTION

There is a paucity of survival data reporting the medium to long-term outcome of the LINK® Endo-Model^® rotational hinge total knee arthroplasty (ERH-TKA). Such information is essential when counselling patients and predictors of survival would help inform patients of their likely outcome.

MATERIALS AND METHODS

A series of patients, who received an ERH-TKA, with a minimum follow-up of 5 years, were retrospectively identified from an established arthroplasty database. Data were collected from paper and electronic patient records. This included patient demographics, indication for surgery, complication rates and revision status. Our primary outcome of interest was joint implant survival.

RESULTS

One hundred patients underwent an ERH-TKA over an 11-year period. There were 66 females and 34 males, with a mean age of 73.8 years and 67.6 years, respectively. Indications were classified into primary (n = 41), aseptic revision (n = 47) and two-stage infective revision (n = 12). The median follow-up was 8.2 (range 5-12) years. One-year implant survival amongst the cohort was 99%, falling to 95% at 5 years. Overall, there were eight revisions during the follow-up period. Considering only cases of aseptic failure, survival was 97% at 5 years and all failures occurred amongst revision cases. Implant failure was greater following revision arthroplasty but this was not statistically significant (p = 0.97). Cox regression analysis identified male sex to be the only independent predictor of failure (hazard ratio 1.75, 95% CI 1.04-31.82, p = 0.04) after adjusting for confounding variables.

CONCLUSIONS

The ERH-TKA has a good medium- to long-term survival rate but male patients are nearly twice as likely to undergo revision, compared to females, and should be made aware of this preoperatively.