Failure rate of a rotating hinge knee design due to yoke fracture of the hinged tibial insert: a retrospective data analysis and review of the literature

Atraumatic dislocation of a modern rotating hinge total-knee prosthesis. A rare but devastating complication

The number of total knee arthroplasties (TKA) is rising in many countries along with the numbers of the revision TKA. Rotating hinge knee (RHK) implants have a fundamental role in the revision TKA and their design has evolved during the last years becoming appealing to many surgeons worldwide. They are mainly used in cases where large bone defects and severe soft tissue imbalance exist. However, despite their recent advancements, they are still associated with high complication rates such as infection, periprosthetic fractures and insufficiency of the extensor apparatus. An uncommon complication of the latest rotating hinge implants is their mechanical component failure. Here we present a rare case of such a devastating complication where a modern RHK prosthesis dislocated without a preceding traumatic event, a review of the corresponding literature and a potential cause for the failure of the mechanism. Moreover, insight on key aspects that need to be addressed is provided, like intrinsic and extrinsic factors which play a crucial role and shouldn't be overlooked for a successful outcome.

A case of an atraumatic implant failure after primary rotating-hinge total knee arthroplasty

Rotating-hinge knee implants are fully constrained knee prostheses commonly used for revision total knee arthroplasty. Nevertheless, rotating-hinge devices have been increasingly utilized in primary setting. Complications are inevitable in orthopedic surgery, however, implant breakage after RHK arthroplasty has been rarely described in medical literature. We present a rare case of 70-year-old Caucasian, male patient who suffered an atraumatic femoral stem breakage in a primary NexGen ® Rotating Hinge Knee (Zimmer-Biomet ® , Warsaw, IN, USA).

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.

Dislocation of rotating-hinge total knee arthroplasty

The number of rotating-hinge total knee arthroplasties (RH-TKAs) is increasing. As a result, the number of complications related to these procedures will also increase.

RH-TKAs have the theoretical advantage of reducing bone implant stresses and early aseptic loosening. However, these implants also have complication rates that cannot be ignored. If complications occur, the options for revision of these implants are limited.

Dislocation of RH-TKAs is rare, with an incidence between 0.7% and 4.4%. If it occurs, this complication must be accurately diagnosed and treated quickly due to the high incidence of neurovascular complications.

If the circulatory and neurological systems are not properly assessed or if treatment is delayed, limb ischemia, soft tissue death, and the need for amputation can occur.

Dislocation of a RH-TKA is often a difficult problem to treat. A closed reduction should not be attempted, because it is unlikely to be satisfactory. In addition, in patients with dislocation of a RH-TKA, the possibility of component failure or breakage must be considered.

Open reduction of the dislocation should be performed urgently, and provision should be made for revision (that is, the necessary instrumentation should be available) of the RH-TKA, if it proves necessary.

The mobile part that allows rotation can have various shapes and lengths. This variance in design could explain why the reported outcomes vary and why there is a probability of tibiofemoral dislocation.

Cite this article: EFORT Open Rev 2021;6:107-112. DOI: 10.1302/2058-5241.6.200093

Metallosis after knee replacement: a review

INTRODUCTION

Although metallosis is a well-known complication after total hip arthroplasty, little is known about this phenomenon after total (TKA) or unicompartmental knee arthroplasty (UKA). The aim of the present work was to review the current knowledge about the reasons and the diagnostic as well as therapeutic management of metallosis after knee arthroplasty.

MATERIALS AND METHODS

A literature search was performed through PubMed until April 2019. Search terms were "metallosis" in combination with "knee", "knee prosthesis", "knee arthroplasty" and "knee replacement", respectively. All publications were analyzed regarding publication year, level of evidence, number of knees/patients treated, type of prosthesis, metallosis cause, time period between primary implantation and metallosis emergence, laboratory examination, treatment, complications and follow up.

RESULTS

A total of 38 studies reporting on a total of 97 knees were identified. 29 studies reported on metallosis after TKA, 8 after UKA, and one study after both procedures. The time period between the primary implantation and metallosis emergence ranged between 6 weeks and 26 years. The most common reason was the failure of a metal-backed patellar component in 40%, followed by implant/structural- and PE failure (wear/dislocation) in 27% and 18% of the cases, respectively. Complete blood cell count, serum chemistry, erythrocyte sedimentation rate or C-reactive protein serum values were not indicative to diagnose metallosis. The diagnosis was confirmed by histopathological analyses and macroscopic evaluation during surgery. Depending on the particular cause various surgical procedures have been performed. Complete prosthesis exchange was the most common one showing no complications in 89.4% of the cases.

CONCLUSIONS

Metallosis after knee arthroplasty is a rare and perhaps underestimated or under published complication. A systematic diagnostic approach is necessary for the timely and correct diagnosis. A thorough debridement as well as a (sub)total synovectomy should be always performed. In cases with a damaged component, a partial/complete prosthesis exchange leads to the best results. Should a malalignment be the cause of the metallosis, then it should be corrected within the revision surgery.

Bilateral Femoral Component Fractures After Primary Total Knee Arthroplasty With Cruciate-Retaining Femoral Component

A 69-year-old male presented with atraumatic bilateral femoral component fractures at different time intervals after simultaneous bilateral total knee arthroplasty using the cemented Biomet Ascent Knee System. The right and left knee implant fractures occurred 12 and 17 years after primary arthroplasty, respectively. This patient was notably tall (190.5 cm, 98th percentile) and maintained an active lifestyle before implant fractures. Sequential, bilateral knee implant fractures in a system with a previously acceptable track record suggest that biomechanics, patient characteristics, and surgical factors can significantly influence the risks for fracture of an implant.

Three-step technique for implantation of rotating hinge knee prostheses : Demonstration using the Enduro prosthesis

OBJECTIVE

Implantation of an axis-guided knee prosthesis with consideration of the joint line and balanced flexion and extension gap to reduce the mechanical load on the prosthesis axis and to improve the movement of the prosthesis.

INDICATIONS

Distinct unilateral instability due to ligament insufficiency in association with knee prostheses. Primary implantation of axis-guided knee prostheses with pronounced axial malalignment (>20-25° valgus or varus malalignment) or/and severe flexion contracture > 40°. Replacement of prosthesis with nonsignificant imbalance between flexion and extension gap.

CONTRAINDICATIONS

Clearly unstable flexion gap such that the extension gap cannot be adjusted appropriately. Significant femoral bone defects requiring distal femoral replacement prostheses.

SURGICAL TECHNIQUE

Reconstruction of the tibial platform with the trial prosthesis with regard to height in relation to the tip of the fibula. Determination of the femoral prosthesis size. Adjustment of the anteroposterior (AP) cutting block of the selected size, referenced anteriorly and in correct rotation. Determination of the flexion gap with spacers using the stable side of the collateral ligaments. Positioning the distal cutting block and determination of the height of the extension gap. Moving the distal cutting block until the same height of spacer as used in the flexion gap fits into the extension gap, taking into account the stable side of the collateral ligaments. The extent of the displacement D1 is noted. Reverse displacement of the distal cutting block by the distance D2 until a satisfactory bony contact surface for the femoral component in the distal femur can be created. The thickness of the required distal augments on the following chamfer-cutting guide (4-in‑1 cutting block) and thus on the femoral prosthetic component is the sum of D1 + D2. The chamfer-cutting guide (4-in‑1 block) with distal augments of the calculated height (D = D1 + D2) is placed in position. Definition and preparation of the posterior contact surface with positioning of any necessary posterior augments. Completion of the femoral preparation taking into account the distal and posterior augments. Assembly of the trial prostheses with a trial inlay having the height of the spacers used. Implantation of the selected prosthesis components.

POSTOPERATIVE MANAGEMENT

Thrombosis prophylaxis, physiotherapy under full weight-bearing and mobility exercises.

RESULTS

After implantation of 104 axis-guided Enduro™ knee prostheses (Aesculap AG, Tuttlingen, Germany) (73 knee prosthesis revisions and 31 primary implantations), the Knee Society Score increased from 42.8 ± 18.8 preoperatively to 84.8 ± 13.9 after 24 months. Complications comprised one deep vein thrombosis and one periprosthetic infection.

How is the outcome of the Limb Preservation System™ for reconstruction of hip and knee?

BACKGROUND

Despite tremendous advantages in the development and application of megaprostheses in tumour and revision surgery, complications are still not infrequently observed. Only two studies investigating the outcome of the LPS™ system in the proximal femur and distal femur/proximal tibia have been published thus far. Herein, mid-term implant survival rates one of the largest cohort of patients treated with the LPS™-system are presented aiming tp answer: 1) How is the outcome of the LPS™ system in the proximal femur and distal femur/proximal tibia? 2) Which factors are associated with altered implant survival? 3) What is the cumulative risk of complications according to Henderson?

HYPOTHESIS

The LPS™-system is associated with high complication rates that depend on implant site, with infections being most common.

PATIENTS AND METHODS

Fifty-seven patients who received the LPS™-system at the proximal femur (n=31), distal femur (n=21) and proximal tibia (n=5) between 2004 and 2010 for oncological (n=40) or non-oncological (n=17) causes, were retrospectively included. Median follow-up was 5.0 years (range, 0-12.4 years). Complications were classified according to Henderson into instability/soft tissue failure (type 1), aseptic loosening (type 2), structural failure (type 3), periprosthetic infection (type 4), tumour progression (type 5). Competing-risk-analyses were applied to estimate implant survival with death as the competing event.

RESULTS

Twenty-six patients (45.6%) developed a complication, of whom 9 (29.0%) had a proximal femoral and 17 (65.4%) a distal femoral/proximal tibial implant. Type 4 complications were most common (n=11), followed by type 3 (n=6, including 2 yoke-fractures), type 1 and 2 (n=4 each), and type 5 (n=1). The only factor associated with the development of complications in the multivariate model was a distal femoral/proximal tibial implant (hazard-ratio: 7.418, 95% confidence-interval: 2.193-26.096, p=0.001), irrespective of reason for reconstruction and use of muscular flaps. The cumulative-incidence of failure including all complications was 34.3%, 40.7% and 67.1% at 3, 5 and 10 years, respectively.

DISCUSSION

The LPS™-system may be used for proximal femoral reconstructions both in the oncological and non-oncological setting. Rates of complications are higher in our cohort than reported in literature for other, comparable, megaprosthesis systems. Especially in the distal femur/proximal tibia, complication rates were high, partially attributable to the former implant design leading to fractures of the yoke-mechanism. As the implant has been remodelled after these issues became evident, there is no objection to use this megaprosthesis system today.

LEVEL OF EVIDENCE

IV, Observational Study.

Total knee arthroplasty using hinge joints: Indications and results

Possible indications for a rotating hinge or pure hinge implant in primary total knee arthroplasty (TKA) include collateral ligament insufficiency, severe varus or valgus deformity (> 20°) with relevant soft-tissue release, relevant bone loss, including insertions of collateral ligaments, gross flexion-extension gap imbalance, ankylosis and hyperlaxity.

The use of hinged implants in primary TKA should be limited to the aforementioned selected indications, especially for elderly patients.

Potential indications for a rotating hinge or pure hinge implant in revision TKA include infection, aseptic loosening, instability and bone loss.

Rotating hinge knee implants have a 10-year survivorship in the range of 51% to 92.5%.

Complication rates of rotating hinge knee implants are in the range of 9.2% to 63%, with infection and aseptic loosening as the most common complications.

Although the results reported in the literature are inconsistent, clinical results generally depend on the implant design, appropriate technical use and adequate indications.

Considering that the revision of implants with long cemented stems can be challenging, in the future it would be better to use shorter stems in modular versions of hinged knee implants.

Cite this article: EFORT Open Rev 2019;4:121-132. DOI: 10.1302/2058-5241.4.180056

Fracture of the insert cone of a polyethylene liner in a failed posterior-stabilized, rotating-platform total knee arthroplasty

Failures unique to posterior cruciate-substituting total knee prostheses rarely include polyethylene post fractures but have been described. We report a case involving a fracture of the distal insert cone of a rotating-platform (RP) polyethylene liner in a primary total knee arthroplasty. This case highlights a 67-year-old male presenting with new-onset knee pain and recurrent effusions with osteolysis 11 years following placement of a posterior-stabilized, RP total knee arthroplasty. At the time of revision surgery, the polyethylene insert cone was found to be fractured just below the junction between cone and the body of the insert. Liner exchange, synovectomy, and osteolytic-defect curettage and cement packing were performed. One year following revision surgery, the patient is without pain and has returned to function without limitations. Clinicians must be aware of this possible failure with RP prostheses in the setting of pain with a stable knee, recurrent aseptic effusions, and osteolysis.

Superior Survivorship of Cementless vs Cemented Diaphyseal Fixed Modular Rotating-Hinged Knee Megaprosthesis at 7 Years' Follow-Up

BACKGROUND

Total knee arthroplasty in the presence of a huge bone and soft-tissue defect is always a challenge. A rotating-hinged (RH) megaprosthesis is indicated for extensive soft-tissue loss with a huge bone defect such as a primary or metastatic neoplasm of the bone, repeat periprosthetic joint infection, or extensive trauma of the knee. However, the reported survivorship of RH megaprostheses is unsatisfactory. The aim of this study was to evaluate the survivorship of megaprostheses and the factors that contribute to implant survival.

METHODS

A total of 103 RH knee megaprostheses were implanted in 85 patients between January 2001 and June 2013. Each prosthesis was a modular custom-made (CM) cemented or cementless fixed total knee system (United USTAR system). Clinical results and prosthesis survivorship were evaluated between the 2 groups.

RESULTS

The overall survivorship of this CM knee megaprosthesis was 91% at 2 years, 83% at 5 years, and 68% at 10 years. The cumulative component survivorship was 87% in the cemented group and 96% in the cementless group at 2 years compared with 75% in the cemented group and 94% in the cementless group at 5 years. The failure mechanism included loosening in 5 and breakage in 6 patients in the cemented stem group. The survivorship of the cementless fixed component was significantly superior to that of the cemented fixed component.

CONCLUSION

Our data suggest that modular RHCM knee megaprosthesis provides an acceptable clinical result. A diaphyseal long stem with cementless fixation was more reliable and durable than its cemented counterpart.

The incidence of implant fractures after knee arthroplasty

PURPOSE

This study aimed to evaluate the incidence of "implant" fractures after knee arthroplasty using clinical literature and worldwide arthroplasty registers. The hypothesis was that register datasets report higher rates of these rare complications than clinical studies.

METHODS

Calculations were based on the pooled incidence of revision operations after fractures of knee arthroplasties, comparing clinical studies published in MEDLINE-listed journals and annual reports from worldwide arthroplasty registers in a structured literature analysis based on a standardized methodology.

RESULTS

Twelve clinical studies and datasets from six worldwide registers were included. Rates of fractures of knee arthroplasties were reported from 0.2 to 2.5 % in clinical studies versus 0.02-0.17 % in worldwide arthroplasty registers.

CONCLUSIONS

Fractures of knee arthroplasty systems are rare complications, with clinical studies showing higher incidence rates than worldwide arthroplasty registries. Unicompartmental knee arthroplasty (UKA) implanted before 2000, constrained primary or revision constrained total knee arthroplasties, and patellar replacements showed the highest incidence of implant fracture. The results of this analysis can help clinicians to counsel patients on potential complications following knee arthroplasty.

LEVEL OF EVIDENCE

III.

Posterior dislocation of the hinge-post extension in a rotating hinge total knee prosthesis

The rotating hinge knee prosthesis is a popular intervention in patients lacking stability with highly constrained total knee arthroplasty. Despite improvements in design, nonmechanical and mechanical complications continue to be a problem. Dislocation of the hinge has been widely described, mainly due to the component fracture. Few reports describe isolated dislocation of the rotating stem. We report a case of isolated disengagement of the rotating hinge mechanism, due to severe flexion gap imbalance, leading to subsequent posterior dislocation of the hinge and anterior knee dislocation, in a patient with a history of multiple total knee arthroplasty revisions. This case suggests the importance of the soft tissue balancing, the adequate patellar tracking, and use of a long cylindrical, minimally tapered rotating stem in hinge arthroplasty to minimize hinge dislocation.

Case report: Failure of rotating-hinge total knee prosthesis by disengagement of the hinge-post extension

BACKGROUND

Although modern-generation rotating-hinge knee implants have been modified to mitigate earlier complications related to aseptic loosening with these devices in revision TKAs, there are few, if any, reports of failure related to the hinge mechanism in these prostheses.

CASE DESCRIPTION

We present a case of disengagement of the hinge-post extension in a contemporary rotating-hinge knee prosthesis originally implanted during revision surgery for instability and extensor mechanism insufficiency. We hypothesize the screw home kinematics of the knee resulted in a counterclockwise torque, contributing to the hinge post locking screw disengagement in this case.

LITERATURE REVIEW

Although some authors have reported complications and failures related to aseptic loosening with rotating-hinge knee prostheses, there have been no reports regarding complications related to the hinge mechanism, which simultaneously links and permits rotation between the femoral and tibial components.

CLINICAL RELEVANCE

Arthroplasty surgeons who use rotating-hinge knee prostheses need to be aware of this potential mode of failure. Design modifications, including more secure locking mechanisms and side-specific implants, may avoid this complication.

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up

PURPOSE

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases.

METHODS

We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips).

RESULTS

Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening.

CONCLUSIONS

The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.