Primary total knee arthroplasty using rotating-hinge prosthesis in severely affected knees

Rotating Hinge Knee Arthroplasty for Charcot Joints of the Knees in Patients With Charcot-Marie-Tooth Disease: A Report of Two Cases

We report two cases wherein rotating hinge knee (RHK) arthroplasty was performed for Charcot joints that developed secondary to Charcot-Marie-Tooth disease (CMT).  Case 1 was of a 74-year-old woman with CMT. She presented with muscle weakness and sensory disturbances of the distal lower limbs, deformity, and significant medial instability of the bilateral knees. She was then diagnosed with Charcot joints of the knees secondary to CMT, which were treated with RHK arthroplasty. Five years postoperatively, there was no instability, and she was able to stand unassisted without pain. Case 2 was a 90-year-old woman with CMT who presented with muscle weakness and sensory disturbances of the distal lower limbs, deformity, and significant medial instability of the bilateral knees. She was then diagnosed with Charcot joints of the knees secondary to CMT, which were also treated with RHK arthroplasty. One year postoperatively, there was no instability, and she was able to walk smoothly using a walker. These clinical cases indicate that RHK arthroplasty can be a good therapeutic option for Charcot joints of the knees in patients with CMT.

Mid- to Long-Term Results of Total Knee Arthroplasty for Charcot Arthropathy of the Knee

Background

Total knee arthroplasty (TKA) for Charcot arthropathy of the knee is considered controversial because of its higher complication rate compared with that of TKA for osteoarthritis. In this study, we investigated the clinical outcomes, survival rates, and complications of primary TKA for Charcot arthropathy.

Methods

We conducted a retrospective analysis of nine patients (12 knees) with Charcot arthropathy who underwent TKA. The mean age of the patients was 63.9 ± 9.4 years (range, 52-83 years). The most frequent causative disease was diabetes mellitus (three patients). Patients' clinical outcomes, including the 2011 Knee Society Score and the range of motion, were compared between preoperative and the most recent postoperative data. The 5- and 10-year survival rates for aseptic revision, revision due to infection, and complications were examined. The mean follow-up period was 7.3 ± 3.9 years (range, 3-14 years).

Results

The 2011 Knee Society Score and the knee flexion angle significantly improved after TKA surgery (P < 0.05). The 5-year survival rates for aseptic revision, revision due to infection, and complications were 100%, 91.7%, and 83.3%, respectively; the 10-year survival rates for these parameters were the same. One patient underwent revision for insert replacement due to periprosthetic infection, and the other patient had varus/valgus instability due to soft tissue loosening.

Conclusions

The mid- to long-term results of TKA for Charcot arthropathy were generally favorable. Our findings indicate that TKA may be a viable treatment option for Charcot arthropathy.

Complex Primary Total Knee Arthroplasty in a Young Patient With Neurofibromatosis Type One and Multidirectional Knee Instability: Technical Tips and Outcome

Neurofibromatosis is an inherited disorder that causes skin discoloration and tumors. The musculoskeletal symptoms are specific, including bone deformities, dysplasia, joint instability, and osteoporosis. We present a rare case of a young patient with neurofibromatosis and multidirectional knee instability who underwent a successful complex primary knee replacement surgery. Stress right knee radiographs showed global joint instability with permanent anterior knee dislocation, excessively hypoplastic femoral condyles and patella, joint surfaces incongruency, and hypoplastic varus tibia, with intraluminal midshaft bone bridge causing severe stenosis. The patient could not walk, had an unstable recurvatum right knee, and used a wheelchair for her professional activities. The surgery involved a fully cemented rotating-hinged total knee arthroplasty with tibial and femoral stems. After three years of follow-up, the patient remains pain-free, fully ambulatory with no walking aids, a stable knee, a full range of motion, and no signs of aseptic loosening. This case highlights the decision-making difficulties and the significant surgical challenges faced during the operation.

Implant survivorship, functional outcomes and complications with the use of rotating hinge knee implants: a systematic review

Background

With more complex primary and revision total knee arthroplasty procedures there is often the need to use more constrained prostheses. This study aims to investigate patient-relevant outcomes following primary and revision rotating-hinged total knee arthroplasty.

Methods

Electronic searches were performed using four databases from their date of inception to January 2021. Relevant studies were identified, with data extracted and analysed using PRIMSA guidelines.

Results

Nineteen studies were included, producing a cohort of 568 primary and 413 revision rotating hinge total knee arthroplasties (TKAs). Survival was assessed at 1-, 5-, and 10-year post-implantation. Sensitivity analyses based on person-time incidence ratios (PTIRs) were prespecified for studies not reporting survival at these timepoints. From the primary hinge TKA cohort, the median survival at 1 year was 93.4% and at 10 years it was 87%. The PTIR at long-term follow-up of this primary cohort was 1.07 (95% CI 0.4–1.7) per 100 person-years. From the revision hinge TKA cohort, the median survival at 1 year was 79.6%, and at 10 years it was 65.1%. The PTIR at long term-follow-up of this revision cohort was 1.55 (95% CI 0.9–2.3) per 100 person-years. Post-operative flexion range of motion (ROM) was 110° for primary hinge TKA and 103° for revision hinge TKA. Compared with baseline, the Knee Society Score (KSS) and Knee Society Function Score (KSFS) improved for both groups post-operatively (primary: KSS 17 to 86, KSFS 28 to 58; revision: KSS 37 to 82, KSFS 34 to 61).

Conclusion

The quality of the evidence for patient-relevant outcomes following hinged knee arthroplasty was limited. While there is the potential for high early revision rates, where successful, large functional benefits may be achieved.

Constraint in complex primary total knee arthroplasty: rotating hinge versus condylar constrained implants

INTRODUCTION

Condylar constrained knee arthroplasties (CCKAs) and rotating hinge knee arthroplasties (RHKAs) achieved good outcomes in complex primary total knee arthroplasties (TKAs); however, long-term comparative studies are few. Using an arthroplasty registry, we sought to assess and compare in CCKAs and RHKAs: (1) the intra-operative rates of complications, (2) the survival rates, (3) the reasons for revision, and (4) the adjusted hazard ratios for failure.

MATERIALS AND METHODS

1432 constrained implants in primary TKAs performed for non-oncological indications were included: 703 RHKAs, 729 CCKAs. The two groups were comparable regarding age and gender. Kaplan-Meier curves were used to compare survival rates, multivariate analyses to assess the hazard ratios for failures.

RESULTS

The mean follow-up was 4.1 years (range 0-16.3) for CCKAs and 6.8 years (0-18.1) for RHKAs. The intra/peri-operative complications were similar in both the cohorts, with similar rates of femoral and tibial fractures. 10-year implant survival rates were similar in both the cohorts (91.9%, CI 95% 89.2-93.9% in RHKAs; 93.4%, CI 95% 90.3-95.6% in CCKAs). Periprosthetic infection was the most common reason for revision in the two cohorts, followed by aseptic loosening. Breakage occurred in 3 RHKAs (0.4%). CCKAs and RHKAs had a similar distribution of revision causes. Males aged less than 60 had significantly more failures, regardless the constraint degree. Unstemmed CCKAs significantly failed more than RHKAs and stemmed CCKAs.

CONCLUSIONS

Both modern CCKAs and RHKAs are viable long-term solutions in complex primary TKAs. More failures should be expected in males aged less than 60.

LEVEL OF EVIDENCE

IV, Therapeutic study.

Preoperative mechanical axis has no influence on reoperation rate in primary rotating-hinge knee arthroplasty

Background

The purpose of the study is to evaluate reoperation rate and its relationship to preoperative mechanical axis of rotating-hinge TKA used as the primary implant in complex knees.

Methods

Patients subjected to primary TKA with a rotating-hinge knee prosthesis due to primary osteoarthritis between 2010 and 2019 were retrospectively reviewed. Preoperative mechanical axis was measured using the last preoperative telemetry x-ray image. Preoperative axis was classified according to the type of deformity (varus or valgus) and its magnitude (0-15°, 16-25° or >25°). Reoperation rate (with or without implant removal) was the primary outcome of the current study. We studied if the preoperative mechanical axis (either varus-valgus, or magnitude of malalignment) was related to implant survival rate.

Results

Forty-two patients were included in the study. Mean follow-up was 51.42 ± 31.88 months. The 83.3% of patients presented a valgus axis while the 16.7% presented a varus axis. Need of reoperation occurred in eight patients (19.0%). However, no patients (0%) required implant removal with revision TKA. No association was seen between the preoperative mechanical axis and risk of reoperation (p = 0.16).

Conclusion

In selected situations that do not permit less constrained implants, primary rotating-hinge arthroplasty could be a good alternative. Risk of reoperation does not seem to depend upon the preoperative mechanical axis when using a rotating-hinge knee prosthesis for primary arthroplasty in non-tumoral complex knees.

Total knee replacements using rotating hinge implants in polio patients: clinical and functional outcomes

Little evidences are available in the literature concerning the outcomes of total knee replacement (TKR) in poliomyelitis patients with severe knee deformities or degeneration. Encouraging results have been reported concerning the use of constrained implants, i.e., rotating hinge knee prosthesis (RHK), compared to less constrained ones. The purpose of this paper is to report our experience with rotating hinge total knee replacement, using only RHK prosthesis, to determine functional results, complications, and survival of TKR in poliomyelitis patients. We performed a retrospective chart review of 14 patients with a history of knee osteoarthritis following poliomyelitis that underwent primary TKR, for a total of 15 surgical procedure (one bilateral case). Preoperative and postoperative clinical measurements have been conducted for all patients using the Knee Society Score (KSS). Hip-knee angle, recurvatum knee angle, and Insall-Salvati index were evaluated with full weight-bearing panoramic view X-ray preoperatively and postoperatively. The 2-year postoperative clinical KSS significantly improved from the preoperative scores. The average clinical KSS improved from 32,9 (range 3-48) preoperatively to 77,4 (range 60-88) postoperatively (P value < 0.005). The average functional KSS improved from 32,5 (range 10-60) preoperatively to 59,4 (range 30-95) postoperatively (P value < 0.005). TKR is a successful treatment in improving knee function and patient's quality of life. Using constrained implants, especially rotating hinge implants in polio patients with a quadriceps muscle weakness, could be a good alternative to maintain a physiological kinematics and reducing the revision rate due to knee instability.

Neuropathic (Charcot) Arthropathy of the Knee

Neuropathic arthropathy of the knee (Charcot knee) is a rare pathology defined by progressive destruction of bone and soft tissue in a patient with underlying peripheral neuropathy. Historically, Charcot knee was associated with neurosyphilis, but it has been increasingly described as a late stage of diabetes. The pathophysiology of the disease is not completely understood, but theories include repetitive microtrauma and an abnormal neurovascular response. Patients present with a warm, swollen, and unstable joint and have rapid bone resorption and characteristic findings on pathology. Nonsurgical options for pain and dysfunction include total contact casting and bracing treatment. Pharmacologic management includes diphosphonates, although this use is considered off-label. Surgical management historically included knee fusion. However, recent case series have suggested that newer prostheses allow for successful arthroplasty in this cohort, although complications are higher when compared with joint arthroplasty in patients with normal neurologic function.

Condylar constrained knee prosthesis and rotating hinge prosthesis for revision total knee arthroplasty for mechanical failure have not the same indications and same results

Purpose: This study aimed to evaluate whether there are any differences in outcomes and complication rates between condylar constrained knee (CCK) and rotating hinge knee (RHK) prostheses used for the first revision of total knee arthroplasty (rTKA) after mechanical failure. Methods: Sixty-three consecutive non-septic revisions of posterior stabilized implants using 33 CCK and 30 RHK prostheses were included. Clinical evaluation and revision rate were compared between the two groups at two years minimum follow-up. Results: The CCK group had significantly better clinical outcomes and satisfaction rates compared to patients with RHK (KSS-knee 70.5 versus 60.7 (p < 0.003) and KSS-function 74.9 versus 47.7 (p < 0.004) at 3.7 (2.0–9.4) years mean follow-up. Moreover, the clinical improvement was significantly higher for the CCK group concerning the KSS-Knee (+23.9 vs. +15.2 points, p = 0.03). The postoperative flexion was significantly better in the CCK group compared to the RHK group (115° vs. 103°, p = 0.01). The prosthesis-related complications and the re-revision rate were higher in the RHK group, especially due to patellofemoral complications and mechanical failures. Conclusions: CCK prostheses provided better clinical and functional outcomes and fewer complications than RHK prostheses when used for the first non-septic rTKA. CCK is a safe and effective implant for selected patients, while RHK should be used with caution as a salvage device for complex knee conditions, with particular attention to the balance of the extensor mechanism.

Custom-built constrained uniaxial and rotating hinge total knee replacement in cats: Clinical application, design principles, surgical technique, and clinical outcome

OBJECTIVE

To describe the design principles and evolution, surgical technique, and outcome for custom constrained (uniaxial and rotating hinge) total knee replacement (TKR) in cats.

STUDY DESIGN

Retrospective case series.

ANIMALS

Nine cats with traumatic stifle luxation (n = 8) or severe distal femoral deformity (n = 1) were considered suitable candidates.

METHODS

Cats that met eligibility criteria and received a custom TKR between 2009 and 2018 by a single surgeon were included in this case series. Three generations of implant were used. Implant positioning was assessed by postoperative orthogonal radiography. Functional outcome was determined by clinical assessment, owner interview, and a feline musculoskeletal pain index questionnaire.

RESULTS

Median clinical follow-up time was 12 months (range, 4-41); follow-up time was increased to 29 months (range, 22-47) when results of functional questionnaires with owner were included. Median radiographic follow-up was 12 months (range, 4-25). One cat had a catastrophic outcome. Three cats had good outcomes, and five cats had excellent outcomes.

CONCLUSION

Most cats treated with custom-built TKR achieved good to excellent outcomes.

CLINICAL SIGNIFICANCE

Custom TKR is a viable option for the treatment of severe pathologies of the feline stifle. Additional research is required to fully evaluate implant suitability.

Bilateral Primary Total Knee Arthroplasty and Reconstruction of the Medial Tibial Plateau by an Asymmetric Cone in a Patient with Charcot Arthropathy

Charcot arthropathy of the knee is an extremely rare orthopedic disease that is very challenging for the treating physician and is associated with many complications, especially if it is occurring on both knees. Meanwhile, in the advanced stage, despite many potential complications, TKA is recognized as the gold standard. However, destruction of the medial tibial plateau is typical for the disease, which makes a stable anchorage of the prosthesis much more difficult. Therefore, we present a case in which sufficient primary stability could be achieved with an asymmetrical second-generation tibial cone with an anatomical design and implantation instruments adapted to the bony anatomy in the presence of severe tibial destruction on both sides. In the two-year follow-up, the patient showed good mobility and stability on both sides. In advanced Charcot arthropathy of the knee, the use of asymmetric tibial cones appears to be an appropriate solution for secure fixation and stability of the implant.

A retrospective comparison of central and posterior hinge joints in 53 total knee arthroplasties

INTRODUCTION

The number of hinged total knee arthroplasty (HTKA) procedures is constantly increasing. There are two hinge types: central (CHTKA) and posterior (PHTKA). The primary purpose of the study was to compare implant survival in patients with CHTKA versus PHTKA. The secondary purpose was to analyse the radiological and clinical results of the implants.

HYPOTHESIS

There is no difference between the two groups.

MATERIALS AND METHODS

This study involved 53 patients who received a HTKA for either primary, trauma or revision surgery, of these 32 were in the CHTKA group and 21 in the PHTKA group, with a mean age of 69 years (38-89). The exclusion criteria were: etiology of sepsis, incomplete records and refusal to use data. The revision rate, with the replacement of prosthetic components, was the primary endpoint. The secondary outcomes were: mobility, complications, VAS, IKS, Devane, Charnley and Oxford knee scores, and radiological progression.

RESULTS

The mean follow-up was 51 months (1-139). At 60 months, overall survival rate of the HTKA was 81%, with a confidence interval (CI) of 95% (71-93.2), and there was no difference between CHTKA and PHTKA, 77.7% (95% CI, 63.3-95.4) versus 85.7% (95% CI, 72-100), p=0.625, respectively. Flexion was 101°±15 (80-140) for CHTKA versus 98°±12 (30-130) for PHTKA, p=0.006. VAS was 0.5±16 (0-6) for CHTKA versus 1.6±14 (0-4) for PHTKA, p=0.000008. The IKS was 103±39 (15-180) for CHTKA versus 81±51 (9-200) for PHTKA, p=0.03. There were no differences in either radiological progression, complications or other functional scores.

DISCUSSION

No significant difference was observed between the survival of CHTKA and PHTKA. CHTKA had better flexion, reduced VAS and increased IKS. Surgeons should be aware of these findings and apply careful consideration to their choice of hinge.

LEVEL OF EVIDENCE

IV; retrospective single-centre study.

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.

Risk Factors for Aseptic Loosening After Total Knee Arthroplasty with a Rotating-Hinge Implant: A Case-Control Study

BACKGROUND

Successful results have been reported in association with the use of a rotating-hinge prosthesis for primary total knee arthroplasty (TKA). The objective of the present study was to identify risk factors for aseptic loosening in patients who underwent primary TKA with rotating-hinge knee prostheses.

METHODS

The records of 1,235 patients who underwent primary TKA with a rotating-hinge prosthesis at our center were evaluated. A total of 125 patients who underwent revision were further evaluated according to the inclusion and exclusion criteria, and 33 patients who underwent revision because of aseptic loosening were then compared with a group of 30 patients who did not require revision surgery. All data, including radiographic measurements, were obtained from records prior to the primary TKA.

RESULTS

On the basis of our review of demographic, anthropometric, clinical, surgical, and radiographic findings, we found that higher body mass index (BMI) was associated with revision. The majority of patients with aseptic loosening had loosening of the femoral component. Furthermore, the inner femoral diameter at 20 cm proximal to the knee joint (on both anteroposterior and lateral images) was found to be predictive of revision among those with aseptic loosening. Receiver operating characteristic curve analysis showed that an inner diameter of the femur of >19 mm on anteroposterior images had a sensitivity of 91% and specificity of 87% for predicting the need for revision surgery in patients with aseptic loosening.

CONCLUSIONS

This is one of few studies that has focused on determining risk factors for the failure of rotating-hinge prostheses following TKA surgery. Our findings indicate that a novel variable, the inner (diaphyseal) diameter of the femur at the point 20 cm proximal to the knee joint, is an extremely reliable predictor of revision surgery in patients with aseptic loosening.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Good mid-term outcome of the rotating hinge knee in primary total knee arthroplasty - Results of a single center cohort of 106 knees with a median follow-up of 6.3 years

BACKGROUND

The prognosis of complex primary total knee arthroplasty (TKA) with severe deformity and ligament deficiency is not clear. There is a paucity of evidence in the current literature on treatment outcomes of the rotating hinge knee implants in primary TKA. The aim of this study was to determine the mid-term clinical, radiographic, and health-related quality of life (HRQoL) outcomes in patients who had undergone complex primary TKA using single hinged knee replacement.

METHODS

In total, 106 complex primary TKAs (101 patients) were performed using the single rotating hinged knee (RHK) implant design at our institution between January 2004 and December 2013. We conducted a retrospective analysis of prospectively collected outcome data of these patients, obtaining also information on all possible revision surgeries from the Finnish Arthroplasty Register, and conducted a prospective follow-up study of all living patients.

RESULTS

The 10-year Kaplan-Meier survival rate of the RHK knees was 91.6% (95% CI 86.0% to 97.2%) with revision for any reason as the endpoint. Overall, eight knees (7.5 %) underwent revision surgery during the follow-up. None of the unrevised RHK knees were radiographically loose. The majority of patients evinced good clinical outcome and quality of life as measured with patient reported outcome measures.

CONCLUSION

The hinge knee replacement which was assessed current study can be regarded as a suitable option in complex primary TKA, provided adequate attention is paid to the correct indications and patient selection.

Can isolated removal of osteophytes achieve correction of varus deformity and gap-balance in computer-assisted total knee arthroplasty?

AIMS

The aims of this study were to determine the effect of osteophyte excision on deformity correction and soft tissue gap balance in varus knees undergoing computer-assisted total knee arthroplasty (TKA).

METHODS

A total of 492 consecutive, cemented, cruciate-substituting TKAs performed for varus osteoarthritis were studied. After exposure and excision of both cruciates and menisci, it was noted from operative records the corrective interventions performed in each case. Knees in which no releases after the initial exposure, those which had only osteophyte excision, and those in which further interventions were performed were identified. From recorded navigation data, coronal and sagittal limb alignment, knee flexion range, and medial and lateral gap distances in maximum knee extension and 90° knee flexion with maximal varus and valgus stresses, were established, initially after exposure and excision of both cruciate ligaments, and then also at trialling. Knees were defined as 'aligned' if the hip-knee-ankle axis was between 177° and 180°, (0° to 3° varus) and 'balanced' if medial and lateral gaps in extension and at 90° flexion were within 2 mm of each other.

RESULTS

Of 50 knees (10%) with no soft tissue releases (other than cruciate ligaments), 90% were aligned, 81% were balanced, and 73% were aligned and balanced. In 288 knees (59%) only osteophyte excision was performed by subperiosteally releasing the deep medial collateral ligament. Of these, 98% were aligned, 80% were balanced, and 79% were aligned and balanced. In 154 knees (31%), additional procedures were performed (reduction osteotomy, posterior capsular release, and semimembranosus release). Of these, 89% were aligned, 68% were balanced, and 66% were aligned and balanced. The superficial medial collateral ligament was not released in any case.

CONCLUSION

Two-thirds of all knees could be aligned and balanced with release of the cruciate ligaments alone and excision of osteophytes. Excision of osteophytes can be a useful step towards achieving deformity correction and gap balance without having to resort to soft tissue release in varus knees while maintaining classical coronal and sagittal alignment of components. Cite this article: Bone Joint J 2020;102-B(6 Supple A):49-58.

Contemporary rotating hinge arthroplasty can safely be recommended in complex primary surgery

PURPOSE

The objective was to evaluate clinical and radiological outcomes, survival rate and complications of primary contemporary rotating hinged total knee arthroplasty (CRH-TKA).

METHODS

Through a national multicenter retrospective study (14 centers), 112 primary CRH-TKA performed between 2006 and 2011 were included. Indications were: severe frontal plane deformity (55%), inflammatory, constitutional, congenital or post-trauma arthritis (26%), ligament laxity (10%), primary osteoarthritis (9%). Population was elderly (68 ± 13), sedentary (37.5% with a Devane score ≥ 3) and with important comorbidities (87% with ASA score ≥ 2). A clinical (KSS, Oxford scores) and radiological evaluation (implant loosening), as well as survival and reoperation rates assessment, were performed.

RESULTS

At last follow-up (7 ± 3 years), KSS and Oxford scores were 64 ± 43 and 33 ± 10 each with a significant improvement of both scores overtime (respectively, p = 0.047 and p < 0.001). Twenty-eight complications (25%) were reported: 12 infections, 6 stiffness, 5 aseptic loosening and 5 patellofemoral instabilities. All in all, 91% (n = 102) of implants were still sealed and in place, 6% (n = 7) required revision and 3% (n = 3) were loose but could not undergo revision due to weak general health status. Mortality rate (18%, n = 20), linked to comorbidities, was high.

CONCLUSION

Clinical outcomes and survival of primary CRH-TKA are acceptable given the difficult and complex clinical situations it faced, but with high infection rate. In primary surgery, for patients with severe deformity, bone loss or ligament laxity, the use of CRH-TKA can be recommended. The choice of these implants must remain cautious and limited to situations not allowing the use of less constrained implants.

LEVEL OF EVIDENCE

Retrospective therapeutic and cohort study, Level III; retrospective case series, Level IV.

Rotating-hinge knee prosthesis as a viable option in primary surgery: Literature review & meta-analysis

BACKGROUND

Rotating-hinge knee replacements are usually reserved for revision surgeries, when the extent of soft tissue loss makes a constrained implant more suitable. They remain an uncommon choice in primary surgery when the soft tissue loss is not as extensive.

METHODS

We completed a systematic review and meta-analysis to assess patients who underwent a Total Knee Replacement (TKR) with the rotating-hinge prosthesis in the primary setting. We searched PubMed and Embase for articles published in the ten years prior June 2017: Prosthesis survival rates, causes of failure, and clinical/functional scores were the primary outcomes. Twenty-one articles met the inclusion criteria for meta-analysis. Articles were grouped into (1) non-tumour (n=11) and (2) tumour indications (n=10). Survival data was summarized in forest plots, generated using Stata.

RESULTS

We found that for certain indications the prosthesis has impressive survival rates and functional outcomes. Short-term (1-5 year) prosthesis survival in non-tumour cases was 92% (95% CI, 87-98%) and 77% (95% CI, 68-87%) in tumour cases. Mid-term (6-10 year) survival was 82% (95% CI, 74-89%) and 69% (95% CI, 57-81%) in non-tumour and tumour studies respectively. In analysis of clinical scores, patients showed a significant improvement in their pain score. Infection was the most commonly cited cause of prosthesis failure in both non-tumour and tumour studies, attributing to 31.5% and 37.6% of failures respectively. Aseptic loosening, dislocation and fracture were also commonly cited complications.

CONCLUSION

We concluded that the rotating-hinge knee prosthesis is a viable option in primary surgery when there is extensive soft tissue destruction surrounding the joint.

LEVEL OF EVIDENCE

I.

Primary constrained and hinged total knee arthroplasty: 2- and 5-year revision risk compared with unconstrained total knee arthroplasty: a report on 401 cases from the Norwegian Arthroplasty Register 1994-2017

Background and purpose - The number of primary, highly constrained knee arthroplasty implants has increased with a theoretically increased risk of early failure. Therefore we analyzed the risk of all revision following total knee arthroplasty (TKA) in patients receiving a hinged or condylar constrained knee (CCK) compared with a conventional unconstrained TKA. Patients and methods - The analyses included 401 primary highly constrained or hinged implants from 1994 to 2017. Kaplan-Meier survival curves were used to evaluate time to first revision with a maximum follow-up of 20 years. Cox regression was used to calculate hazard ratio (HR) comparing condylar constrained knee (CCK), hinged, and unconstrained TKA. Results - Kaplan-Meier estimated prosthesis survival after 2 years was 94.8% (95% CI 91.4-98.2) and 93.5% after 5 years for the primary CCK and 91.0% (CI 86.6-95.4) after 2 years and 85.5% after 5 years for the primary hinged TKA. Adjusted for sex, age groups, diagnosis, time period, previous surgery, and surgery time HR was 1.4 (CI 0.8-2.3) for the CCK and 2.4 (CI 1.6-3.7) for the hinged implants. The most common cause of revision in hinged implants was infection: 14 of 22 revisions. When excluding infection as revision cause, there were no differences in survival between the implant types. Estimated survival excluding infection revisions at 5 years was 96% for unconstrained, CCK, and hinged primary TKA implants. Interpretation - Primary rotating hinge total knee arthroplasty had a higher risk of revision compared with conventional TKA after 2 and 5 years' follow-up. Infection was the most common cause of revision. When excluding infection revisions from the survival analysis, hinged and CCK implants had similar performance to unconstrained TKA.

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.

Good clinical and radiological results of total knee arthroplasty using varus valgus constrained or rotating hinge implants in ligamentous laxity

PURPOSE

The optimal degree of constraint of a total knee arthroplasty for treatment of knee osteoarthritis with ligamentous laxity is under debate. While varus valgus constrained knees require a minimum level of ligamentous stability, rotating hinge knees can even be implanted if the collateral ligaments have been lost completely. It seems plausible that joint kinematics are determined by implant design in rotating hinge knees, whereas varus valgus constrained knees may be influenced by remaining stabilizers. This may result in more predictable clinical results of hinge knees. The hypothesis of the present study, therefore, was that stability and clinical outcome are better after total knee arthroplasty using rotating hinge knees than after using varus valgus constrained knees.

METHODS

All patients who were treated using a mobile-bearing varus valgus constrained knee or a rotating hinge knee for treatment of end-stage osteoarthritis and ligamentous laxity were included. At follow-up, clinical scores were determined (WOMAC, VAS, KSS, FJS, Lysholm). Furthermore, body mass index, operating time, and postoperative complications were documented. Whole leg radiographs as well as patella axial radiographs were analyzed for implant alignment and patella tracking.

RESULTS

Eighty-five patients were included in this retrospective study. Both groups showed an average range of motion of 113°. No significant difference between the two groups was observed for any of the scores recorded. In the rotating hinge knee group, a more precise tibia positioning in relation to the mechanical axis but also a significant lateralisation and tilting of the patella were seen, compared with the varus valgus constrained knee group.

CONCLUSIONS

Rotating hinge knees did not perform better than mobile-bearing varus valgus constrained knees clinically. Both prosthesis types showed equally good clinical outcomes with regard to stability, mobility, satisfaction, pain and operating time.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

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

Risk factors for ileus after hip and knee arthroplasty

PURPOSE

Postoperative ileus (POI) is one of the complications that can occur after every surgical procedure including arthroplasty. It can have detrimental consequences for the patient and portrays an economic burden on health care systems. The risk factors for POI after arthroplasty described in the literature are scarce and include hip arthroplasty, male gender and previous abdominal surgery. The purpose of the study was to determine the risk factors for POI after hip and knee arthroplasty.

METHODS

A retrospective review of 2760 patients undergoing primary hip and knee arthroplasty was performed. An in-depth analysis of patient history and physical operative and postoperative course was reviewed and statistically analyzed in a univariate and multivariate setting.

RESULTS

Overall incidence of POI was 0.54%. History of myocardial infarction and chronic kidney disease were statistically significant risk factors for developing POI after arthroplasty with values of p = 0.023 and p = 0.004, respectively. Other risk factors included previous abdominal surgery (p < 0.001) and hip arthroplasty (p = 0.026). Age or gender correlations were not observed.

CONCLUSIONS

Although postoperative ileus is an uncommon complication after joint arthroplasty, in addition to the known risk factors of male age, hip arthroplasty, and previous abdominal surgery, this study describes two previously unknown risk factors: chronic kidney disease and history of myocardial infarction. Patients with these risk factors should be monitored closely for developing postoperative ileus.

Total knee arthroplasty in patients with multiple hereditary exostoses

We present a case report of a patient with severe valgus deformity of the right knee due to multiple hereditary exostoses (MHEs) treated with total knee arthroplasty (TKA). The surgical management of MHE affecting the knee encompasses exostoses resection, joint deformity rectification, and limb-length discrepancy alignment. On rare occasions, distraction osteogenesis and TKA have been used to correct valgus deformities of the knee. TKA in MHE patients with knee involvement has only been described in 6 cases. Several considerations, such as extensive knowledge of frequently occurring skeletal aberrations, are required to successfully correct the deformities associated with MHE via TKA. This report describes a case of severe valgus knee deformity with a rotational component in MHE managed with TKA, the surgical technique, and future recommendations.

Primary Total Knee Arthroplasty in Patients With Neuropathic (Charcot) Arthropathy: Contemporary Results

BACKGROUND

Total knee arthroplasty (TKA) for neuropathic (Charcot) arthropathy is technically challenging with higher complication rates than primary TKA for osteoarthritis. There is a paucity of data regarding outcomes of TKA in contemporary cohorts with modern implants, techniques, and indications. Our study aimed to determine the (1) survivorship of implants, (2) rates and types of complications, (3) clinical outcomes, and (4) radiographic outcomes in patients treated with primary TKA for Charcot arthropathy.

METHODS

Twenty-seven patients undergoing 37 TKAs for Charcot arthropathy from 2000 to 2015 were retrospectively reviewed. Mean patient age and follow-up were 60 years and 6 years, respectively. Eighty-one percent were treated with either a varus-valgus constrained or rotating-hinge device, and 81% had supplemental stem fixation. Metaphyseal cones were utilized in 19% of cases.

RESULTS

The 10-year survivorship free of aseptic revision was 88% and free of any revision was 70%. There were 6 revisions (16%): 4 for infection, 1 for tibial component loosening, and 1 for global instability. There were 3 reoperations (8%). Additional complications occurred in 6 patients (16%) including 3 patients with an intraoperative fracture. Mean Knee Society scores improved from 37 preoperatively to 82 postoperatively (P < .001). There was no radiographic evidence of component loosening in any unrevised knee at latest follow-up.

CONCLUSIONS

Primary TKA for Charcot arthropathy with selective use of increased constraint and enhanced metaphyseal component fixation led to significant improvement in pain and clinical outcomes when compared with older techniques; however, there was a high perioperative complication rate. While 10-year survivorship free of aseptic revision was 88%, periprosthetic joint infection led to the poorer survivorship free of any revision of 70% at 10 years.

LEVEL OF EVIDENCE

Level IV.

Knee arthroplasty with rotating-hinge implant: an option for complex primary cases and revisions

Objective

To present the indications, technical aspects, and initial results of the first cases using Endo-Model™ implants in Brazil.

Methods

A prospective study was conducted. It included nine patients submitted to a total knee arthroplasty, of which six were primary and three were revisions, using exclusively the Endo-Model™ implant. These patients were followed for an average of 12 months and evaluated with functional scores, such as the Knee injury and Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS), and visual analog pain scale (VAS).

Results

There were statistically significant improvements in all scores evaluated in every patient. Only one complication occurred postoperatively (apraxia of the peroneal nerve) and did not require surgery revision.

Conclusion

The use of a rotating-hinge implant for knee arthroplasty is a new option for complex cases with severe instability in Brazil; the initial results are satisfactory.

Midterm Results of a New Rotating Hinge Knee Implant: A 5-Year Follow-Up

Background

In the current study, we investigated midterm results of a new rotating hinge total knee arthroplasty (EnduRo prosthesis), which uses a new bearing material (CFR PEEK).

Methods

We prospectively analysed data of 50 patients with a minimum follow-up of 5 years. In 24 (48%) patients, a primary implantation was performed and 26 (52%) were revision cases. Clinical and radiographic examinations were performed preoperatively as well as postoperatively after 3 and 12 months and annually thereafter. The Knee Society Score (KSS), WOMAC, Oxford Knee Score (OKS), and range of motion (ROM) were used for clinical assessment.

Results

KSS, WOMAC, OKS, and ROM significantly improved between the preoperative and the follow-up investigations. The overall survival rate with revision for any reason as an endpoint was 77.9% after five years. The number of complications was significantly higher in the revision group (p = 0.003).

Conclusion

The EnduRo prosthesis provides highly satisfying clinical and functional results in severe primary as well as in revision cases. Implant-associated complications were rare. However, in cases of revision surgery, the risk for complications was considerably high, mostly related to previous joint infections and poor soft tissue quality.

Understanding the human knee and its relationship to total knee replacement

The knee is the intermediate joint of the lower limb and it allows the movement between the femur, tibia and patella. Under normal conditions there is a normal distribution of the load forces on these three articular components in both the static load and during ambulation. The understanding of anatomy and knee biomechanics is important for the gait analysis, the diagnosis of joint diseases and the design and development of prosthetic implants. In the last decades comprehension of knee physiology and kinematics has led to the introduction of a wide range of enhanced prosthetic implant designs for a variety of indications. There are a number of types of total knee arthroplasty implant designs, which are intended to offer the surgeon options for individual patients. The various choices imply that each specific problem has a corresponding implant that provides a reliable solution. However, until the current date, it has not been possible to produce a prosthetic design fully restoring the complex kinematics of the normal knee joint.

Complex Primary Total Knee Arthroplasty: Long-Term Outcomes

BACKGROUND

Total knee arthroplasty in patients with severe preoperative deformity, ligamentous instability, and/or marked bone loss occasionally requires a varus and valgus constrained or rotating-hinge design prosthesis. The purpose of this study was to compare patient populations that underwent primary total knee arthroplasty with constrained or unconstrained total knee arthroplasty implants to determine patient demographic characteristics, long-term survival, and reasons for reoperation and revision for each group.

METHODS

We identified 28,667 primary total knee arthroplasties performed from 1979 to 2013 at our institution. A total of 427 knees had a varus and valgus constrained design and 246 knees underwent rotating-hinge total knee arthroplasties. Patient demographic information and preoperative diagnoses were analyzed by implant type. A multivariate analysis was performed to account for age, sex, and body mass index (BMI). Kaplan-Meier survival rates for each complication leading to reoperation or component revision were determined at 10 and 20 years. Adjusted hazard ratios were determined for the most common causes for reoperation and revision compared with a routine total knee arthroplasty control group.

RESULTS

Patient demographic characteristics were significantly different (p < 0.05) between all groups for age, sex, and BMI. The varus and valgus constrained and rotating-hinge groups had decreased survival free of all-cause reoperation at 10 and 20 years compared with the unconstrained total knee arthroplasty group, with a hazard ratio of 1.74 (95% confidence interval [95% CI], 1.36 to 2.23) for the valgus and varus constrained group and 2.07 (95% CI, 1.58 to 2.70) for the rotating-hinge group. The adjusted hazard ratio for all-cause revision was significantly higher for the varus and valgus constrained group at 1.65 (p = 0.007) but not for the rotating-hinge group at 1.48 (p = 0.054) compared with the unconstrained total knee arthroplasty group. Wear and osteolysis, infection, and fracture were the most common reasons for component revision in both groups.

CONCLUSIONS

We found increased reoperation and revision rates associated with the use of constrained implants at the time of index total knee arthroplasty. The rate of component revision for any reason at 10 years was >2 times higher in the constrained total knee arthroplasty groups compared with the unconstrained total knee arthroplasty group. At 20 years postoperatively, the component revision rate was >3 times higher.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Computer-assisted navigation is beneficial both in primary and revision surgery with modular rotating-hinge knee arthroplasty

PURPOSE

The objective of the present study was to explore the effect of navigation on the reconstruction of the mechanical leg axis, implant positioning and the restoration of the joint line in hinged knee arthroplasty in vivo. We present the first 1- to 3-year clinical and radiological results following computer-navigated implantation of the EnduRo modular rotating-hinge knee arthroplasty system (Aesculap AG, Tuttlingen, Germany) as a primary or revision implant.

METHODS

Thirty-one patients were analysed retrospectively. Indication was revision surgery in 18 patients and complex primary surgery in 13. The clinical and radiological results of 31 patients with a minimum follow-up of 12 months (mean 22.2 ± 6.2 months) were recorded. Age at follow-up was 55.2 ± 9.9 years.

RESULTS

The absolute varus-valgus deviation from the neutral mechanical leg axis was determined at 5.1° ± 5.1° preoperatively and 2.1° ± 1.4° postoperatively. No intraoperative complications or problems with the navigation system were observed. At latest follow-up, no component loosening was detected. Based on the Knee Society Score, a knee score of 64.9 ± 17.7 points and a function score of 67.2 ± 27.3 points were achieved.

CONCLUSIONS

Encouraging short-term clinical and radiological results with the computer-navigated implantation of the modular rotating-hinge EnduRo knee arthroplasty system were found in both primary and revision surgery. The navigation facilitated the reconstruction of the leg axis, implant positioning and the restoration of the joint line.

LEVEL OF EVIDENCE

IV.

A clinical study of the rotational alignment of the femoral component in total knee arthroplasty

[Purpose] The reasons for femorotibial rotational malalignment after total knee arthroplasty (TKA) were analyzed to provide evidence for clinical knee joint surgery and to reduce complications. [Subjects and Methods] Ninety knees of 60 patients were selected and randomly divided into two groups (n=30). For one group, rotational alignment of the femoral component was determined by the transepicondylar axis and TKA was performed. For the other group, rotational alignment of the femoral component was conducted through 3° external rotation of the posterior femoral condyles. Knee joint specimens were operated with TKA and various biomechanical indices were measured. [Results] The femoral epicondylar axis was a constant, reliable reference for femoral component rotational alignment. When the femoral component was rotated by 0° versus the epicondylar axis, the peak contact pressure on the patellofemoral joint was optimal. When the femoral component was arranged in parallel with Whiteside's line, the peak contact pressure on the patellofemoral joint varied largely. The patellofemoral contact areas of the two groups were similar. [Conclusion] Axial rotational alignment of the femoral component influenced the contact pressure of patellofemoral joints in TKA more significantly than external rotation of the femoral condyles. It is more reliable to use the femoral epicondylar axis as the reference for the rotational alignment of the femoral component.

Posttreatment imaging of pediatric musculoskeletal tumors

Pediatric patients who are diagnosed with musculoskeletal tumors often require serial imaging both during and after treatment. Although many of the treatments used in adults overlap with those used in children and adolescents, the growing skeleton presents specific challenges that require a unique approach. Surgical treatment of benign osseous lesions typically requires only curettage and bone grafting, whereas that of osseous malignancies generally consists of wide excision and limb salvage, with either endoprosthetic or biologic reconstruction. Current conventional endoprostheses consist of modular components that allow intraoperative customization; however, if there is great potential for future growth, an expandable endoprosthesis may be required. Biologic reconstruction may consist of an allograft and/or autograft and, in some circumstances, can spare the growth plates in a child, thereby allowing normal growth. Expected posttreatment imaging findings in soft-tissue tumors may include muscle flaps and postoperative fluid collections. Medical treatment, including radiation therapy and chemotherapy, can have predictable imaging manifestations, including signal alterations in bone marrow, muscle, and subcutaneous fat. Finally, treatment complications may manifest with clinical symptoms and include infection or mechanical failure, although other complications such as local tumor recurrence may go clinically undetected until surveillance imaging. Familiarity with the expected posttreatment imaging findings in pediatric patients with musculoskeletal tumors can aid in the detection of complications.

The role of hinges in primary total knee replacement

The use of hinged implants in primary total knee replacement (TKR) should be restricted to selected indications and mainly for elderly patients. Potential indications for a rotating hinge or pure hinge implant in primary TKR include: collateral ligament insufficiency, severe varus or valgus deformity (>20°) with necessary relevant soft-tissue release, relevant bone loss including insertions of collateral ligaments, gross flexion-extension gap imbalance, ankylosis, or hyperlaxity. Although data reported in the literature are inconsistent, clinical results depend on implant design, proper technical use, and adequate indications. We present our experience with a specific implant type that we have used for over 30 years and which has given our elderly patients good mid-term results. Because revision of implants with long cemented stems can be very challenging, an effort should be made in the future to use shorter stems in modular versions of hinged implants.

Total knee arthroplasty with rotating-hinge Endo-Model prosthesis: clinical results in complex primary and revision surgery

INTRODUCTION

Rotating-hinge knee implants are highly constrained devices able to provide the stability needed for arthroplasty in case of severe bone loss and complex instability. Notable doubts still exist in using rotating-hinge devices, mainly due to risk of mechanical failure and risk of infection.

MATERIALS AND METHODS

We retrospectively evaluated the functional and clinical outcomes in a series of patients treated with the rotating-hinge Endo-Model prosthesis either for primary or revision total knee arthroplasty. Between 1997 and 2009 we implanted 123 Endo-Model prosthesis (118 patients) at our institution. At the time of this study we could evaluate 45 prosthesis (25 primary and 20 revision TKAs) from the clinical and radiological site, with average follow-up of 42.2 months.

RESULTS

During the follow-up period, three patients reported complications, which in two cases finally led to revision with explantation. Mean survival of the implants attested at 93.3 %. The average post-operative clinical Knee Society score in the evaluated series was 94.2, the functional one 78.7. The average range of motion was 0°-108°. No signs of joint instability or misalignment were noted. Pain was present in a minority of patients, but always at a mild/occasional extent. No evidences of loosening or implant failure have been reported. No substantial divergences in the outcomes have been found across different patient categories after stratification in agreement with the Knee Society.

CONCLUSIONS

Coherent with previously published works, we confirm the Endo-Model prosthesis to provide excellent pain relief, restoration of walking capacity and intrinsic knee stability both in complex primary and in revision knee arthroplasty, with good or excellent results in the majority of patients and acceptable complication rate.

Early results of a new rotating hinge knee implant

Background. Indication for rotating hinge (RH) total knee arthroplasty (TKA) includes primary and revision cases, with contradictory results. The aim of this study was to report prospective early results of a new modular rotating hinge TKA (EnduRo). For this implant several new design features and a new bearing material (carbon-fiber reinforced poly-ether-ether-ketone) have been developed. Furthermore, we tried to establish a new classification of failure modes for revision TKA. Methods. 152 EnduRo rotating-hinge prostheses were implanted in two centers. In 90 patients a primary implantation has been performed and 62 patients were revision cases. Knee Society Score (KSS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), and Range of motion (ROM) were assessed before surgery, 3 months postoperatively, 12 months postoperatively, and annually thereafter. We defined 3 types of complications: Type 1, infection; type 2, periprosthetic complications; type 3, implant failures. Results. KSS, WOMAC, OKS, and ROM revealed significant improvements between the preoperative and the follow-up investigations. There were 14 complications (9.2%) leading to revision surgery, predominantly type 2. Conclusion. Our study shows excellent clinical results of the EnduRo TKA. Furthermore, no premature material failure or unusual biological response to the new bearing material could be detected.

Primary rotating-hinge total knee arthroplasty: good outcomes at mid-term follow-up

We evaluated the clinical and radiologic outcomes of primary knee replacements using a rotating-hinge knee prosthesis in 12 knees with a minimum follow-up of 10 years. Indications for the operation included gross joint destruction, significant axial deformities and contracture with a dysfunctional medial collateral ligament in all cases. The patients' WOMAC and Knee Society scores improved, and the use of mobility aids decreased. No loosening of implants was observed. Nonprogressive radiolucent lines were identified around three tibial components. Three patients required marginal wound excision with resuturing and thereafter healed uneventfully. With significant improvement in function, pain and range of motion, the rotating-hinge knee prosthesis can be used as a salvage device in patients with medial collateral ligament deficiency, contracture, and gross joint destruction.

Mid-term survival following primary hinged total knee replacement is good irrespective of the indication for surgery

PURPOSE

The use of 'hinged' knee prostheses for primary knee arthroplasty procedures is increasing. This analysis reports the rates of implant survival, modes of failure, revision details and functional outcomes with particular reference to the primary indication for surgery for a cohort of patients treated with primary hinged knee replacement.

METHODS

Systematic review with supplementary analysis using data from the National Joint Registry and Department of Health. Analysis included 964 patients undergoing primary hinged knee replacement between April 2003 and December 2010. Survival at a maximum of 7 years was calculated for the group as a whole and dependent upon the indication for surgery (osteoarthritis vs. rheumatoid/inflammatory arthritis vs. post-traumatic arthritis). Functional outcomes (pre- and post-operative Oxford Knee and Euroqol-5D scores and post-operative satisfaction) were available for 46 patients.

RESULTS

In total, 20 cases required revision. The 5-year survival rate (96.8% [95% CI 95.1-98.4%]) was not dependent upon the primary surgical indication (p = n.s.). The commonest reasons for revision were infection (8 cases), peri-prosthetic fracture (4 cases) and aseptic loosening (3 cases). Patients reported substantial improvements in their Oxford Knee Score (mean improvement = 17.6, [95% CI 14.4-20.8]) and EQ5D index (mean improvement = 0.357, [95% CI 0.248-0.467]). Levels of post-operative satisfaction were high.

CONCLUSIONS

Hinged knee replacement can be considered as a viable alternative to more traditional unconstrained designs in the complex primary setting. These findings are clinically relevant as they support the increasing use of hinged knee replacements for the arthritic knee in which there is concomitant severe bone loss, deformity or instability. Surgeons using these implants can have confidence that their mid-term performance is comparable to more conventional knee designs.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Clinical biomechanics of instability related to total knee arthroplasty

BACKGROUND

Tibiofemoral instability is a common reason for total knee arthroplasty failure, and may be attributed to soft tissue deficiency and incorrect ligament balancing. There are many different designs of implant with varying levels of constraint to overcome this instability; however there is little advice for surgeons to assess which is suitable for a specific patient, and soft tissue balance testing during arthroplasty is very subjective.

METHOD

The current theories on primary and secondary soft tissue restraints to anterior/posterior, varus/valgus, and internal/external rotational motion of the knee are discussed. The paper reviews biomechanics literature to evaluate instability in the intact and implanted knee.

FINDINGS

The paper highlights important intra- and extra-capsular structures in the knee and describes the techniques used by clinicians to assess instability perioperatively. In vitro cadaveric studies were found to be a very useful tool in comparing different implants and contributions of different soft tissues.

INTERPRETATION

In vitro cadaveric studies can be utilised in helping less experienced surgeons with soft tissue releases and determining the correct implant. For this to happen, more biomechanical studies must be done to show the impact of release sequences on implanted cadavers, as well as determining if increasingly constrained implants restore the stability of the knee to pre-deficient conditions.

Results with 98 Endo-Modell rotating hinge prostheses for primary knee arthroplasty

Rotating hinge knee prostheses have been developed as an advancement of the fixed hinge models. Some authors suggest that this type of prosthesis is associated with a greater risk of aseptic loosening because of the increased stresses to the bone-prosthesis interface; therefore, they are scarcely used as primary implants. The current authors evaluated of a series of 98 rotating hinge knee arthroplasties Endo-Modell (Waldemar LINK GmbH and Co, Hamburg, Germany) implanted for knee osteoarthritis. The Hospital for Special Surgery Knee Score and the Knee Society Score were used for the clinical and radiographic evaluation. Log-rank or Wilcoxon tests were used to test the statistical significances, and the Kaplan-Maier method was used to calculate the implant survival probability. After a medium follow-up of approximately 174 months, the clinical scores showed a statistically significant improvement from the pre- to postoperative period. The complication rate was high, and the cumulative implants survival rate was 88.7% at 1 year, 85.9% at 5 years, 79.8% at 10 years, and 75.8% at 15 years. The Endo-Modell rotating hinge implants demonstrated no significant risk of aseptic loosening, and the hinge was not a primary cause of failure. However, the overall failure rate was higher than that of unhinged implants; therefore, this prosthesis is recommended for cases of instability and revision rather than primary knee arthroplasty.

Constraint choice in revision knee arthroplasty

PURPOSE

Along with the increase in primary total knee arthroplasty, there has been an increase in the number of revisions. The aim of this study was to propose a selection algorithm for the knee revision constraint according to the state of ligaments and to the bone defects Anderson Orthopaedic Research Institute Classification [AORI] classification. The hypothesis was that this algorithm would facilitate the appropriate choice of prosthesis constraint, thus providing stable components and a good long-term survivorship of the knee revisions.

METHODS

Sixty consecutive revision knee arthroplasties in 57 patients were prospectively evaluated. Prostheses implanted at revision included postero-stabilised, condylar constrained and rotating hinged, relative to the state of the ligaments and of the bone loss around the knee. The median follow-up was nine years (range, 4-12).

RESULTS

The median IKS knee and function scores and HSS score were 41 (15-62), 21.5 (12-43) and 34 (23-65) points, respectively, before the operation, and 81 (48-97), 79 (56-92) and 83.5 (62-98) points (p < 0.001) at the latest follow-up evaluation. The median ROM increased from 74° (29-110°) preoperatively to 121° (98-132°) (p < 0.01) at the final follow-up. Re-revision was necessary in five (8.3%) patients.

CONCLUSIONS

A selection algorithm for the revision implant constraint based on the state of ligaments and the bone loss AORI classification could provide stable knee reconstructions and long-term success of knee revisions.

Mid-term results after implantation of rotating-hinge knee prostheses: primary versus revision

The aim of the study was to evaluate the mid-term clinical results and survivorship of a rotating-hinge knee prosthesis (LINK® Endo-Model) in difficult primary and complex revision situations. Results after primary implantation were compared with those of revision procedures. Forty-nine prostheses in 45 patients were reviewed clinically during follow up. Twenty-one of these were implanted in primary and 28 in revision situations. Outcome was evaluated using commonly used scores (Knee Society, UCLA Activity, Lequesne) and a visual analog scale after a mean follow up of 56±37 months for 49 prostheses. Implant survival was analyzed using the Kaplan-Meier method. There were no significant differences in clinical examination and evaluation scores between the two groups (P>0.05). Survival rates at final follow up were 95% after primary implantation and 76% in revision procedures. The risk of prosthesis loss (odds ratio 5.7) was significantly higher after revision procedures (P=0.004). These data suggest that rotating-hinge knee prostheses provided good clinical and functional results in selected cases of advanced primary gonarthrosis associated with severe bone loss, ligamentous instability or comminuted fractures. They also provide good results in revision situations. However, the failure rate was significantly higher in cases of revision surgery.