The cemented inset biconvex patella in revision knee arthroplasty

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

Biconvex Patellar Components: 96% Durability at 10 Years in 262 Revision Total Knee Arthroplasties

BACKGROUND

The optimal strategy to address osseous deficiencies of the patella during revision total knee arthroplasty (TKA) remains controversial. One possible solution is a cemented biconvex patellar component used such that the non-articular convexity both improves fixation and makes up for bone loss. The aim of this study was to determine the outcomes of the use of biconvex patellar components in a large series of revision TKAs.

METHODS

From 1996 to 2014, 262 revision TKAs were performed at a single institution using a biconvex patellar component. Implant survivorship, clinical and radiographic results, and complications were assessed. The mean patient age at the TKA revision was 69 years, and 53% of the patients were female. The mean follow-up was 7 years.

RESULTS

The 10-year survivorship free of revision of the biconvex patellar component due to aseptic loosening was 96%. The 10-year survivorship free of any revision of the biconvex patellar component was 87%. The 10-year survivorship free of any rerevision and free of any reoperation was 75% and 70%, respectively. The mean Knee Society Score (KSS) improved from 45.4 before the index revision to 67.7 after it. The mean residual composite thickness seen on the most recent radiographs was 18.1 mm. In addition to the complications leading to revision, the most common complications were periprosthetic patellar fracture (6%), of which 3 required revision; superficial wound infection (6%) requiring antibiotic therapy only or irrigation and debridement; and arthrofibrosis (3%).

CONCLUSIONS

In this cohort of 262 revision TKAs, biconvex patellar components used to treat marked patellar bone loss demonstrated excellent durability with a 10-year survivorship free of patellar rerevision due to aseptic loosening of 96%. The biconvex patellar components were reliable as evidenced by substantial improvements in clinical outcomes scores and a low risk of complications.

LEVEL OF EVIDENCE

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

Patellar Bone-Grafting for Severe Patellar Bone Loss During Revision Total Knee Arthroplasty

Background

Treatment of severe patellar bone loss during revision total knee arthroplasty (TKA) is difficult. Patellar bone-grafting is a simple procedure that can improve patient outcomes following revision TKA.

Description

The patient is prepared and draped in the usual sterile fashion. The previous longitudinal knee incision is utilized for exposure. Scar tissue is excised from the medial gutter. However, tissue in the lateral gutter is largely maintained. An assessment of the surrounding quadriceps and patellar scar tissue ensues. This tissue can be utilized to create an envelope for holding the bone graft in place. If insufficient tissue is present, fascia from the iliotibial band or vastus medialis, allograft fascia, or synthetics can be used.A careful assessment of component fixation and rotation is critical to the success of patellar bone-grafting. Component revision for aseptic loosening or malrotation should be performed in the usual fashion. During component revision, it is recommended to preserve any additional bone as autograft for the patellar bone-grafting procedure. Common sites of autograft harvest include the femoral box cut and proximal tibial resection.The patella is then addressed by carefully removing the previous implant to avoid additional bone loss. This step is performed with a combination of an oscillating saw, osteotomes, and high-speed burr. The retropatellar bone is then prepared by debriding excess soft tissue, cysts, or cement. A high-speed burr is then utilized to produce a punctate bleeding surface for bone-graft incorporation.The harvested tissue is closed around the perimeter of the patella with use of interrupted nonabsorbable sutures, leaving a window to pack in the bone graft. The bone graft (allograft and autograft) is morselized and place through the window.The optimal patellar thickness is variable. After packing the bone graft through the soft-tissue window, the thickness is measured with a caliper. It is recommended to acquire a thickness of >20 mm because bone-graft resorption and remodeling occur with knee range of motion. The remaining soft-tissue window is closed with use of nonabsorbable sutures. The knee is cycled through a range of motion to ensure optimal patellofemoral tracking. If necessary, a lateral release or medial soft-tissue advancement can be performed to ensure patellofemoral tracking is adequate. Finally, the wound is irrigated and closed in layers.

Alternatives

Nonsurgical:Patellar knee braceHinged knee braceSurgical:Gull-wing osteotomyPatellar resurfacing with biconvex patellaBulk allograft reconstructionPartial or complete patellectomyPatelloplastyInterpositional arthroplastyTantalum metal-backed reconstruction.

Rationale

There is a myriad of surgical options for severe patellar bone loss following TKA. Patellar bone-grafting is simple, reproducible, and relatively cost-effective^1,2, and avoids the need for the amount of bone for reconstruction that may be required for metal-backed or biconvex patellar implants^3,4. The procedure allows for the restoration of the quadriceps lever arm, which may not be restored with other techniques, such as gull-wing osteotomy or patellectomy⁵. Patellar bone-grafting avoids the cost and risks of disease transmission associated with allograft reconstruction⁶. Finally, the procedure provides excellent long-term survivorship and patient-reported outcomes.

Expected Outcomes

Following this procedure, patients should experience a reduction in knee pain and improved patient-reported outcomes^2,6, with a prior study showing that the percentage of patients reporting anterior knee pain decreased from 51% to 27% following patellar bone-grafting. Patients also demonstrated an improvement in knee range of motion, with a mean increase in knee flexion of 7^o and knee extension of 2^o1. Complications related to this procedure are minimal. Bone stock restoration can be utilized for patellar resurfacing in the future¹. Radiographically, patellar bone resorption, loss of patellar height, and patellar remodeling do occur; however, despite these radiographic changes, Knee Society scores increased from 50 to 85 at the time of the latest follow-up.

Important Tips

Careful preoperative physical examination should document range of motion, areas of pain, and patellofemoral tracking and/or instabilityBe prepared to revise the femoral and/or tibial components if malrotated in order to optimize patellofemoral trackingRetain any autogenous bone harvested during component revision to use as patellar bone graftEnsure that allograft bone is available to ensure sufficient restoration of patellar thicknessConsider having allograft tissue available in the event that scar tissue in situ is not adequate to create an envelope for packing the bone graftA bleeding retropatellar surface prepared with a high-speed burr will increase the chance of bone incorporationA watertight closure of the soft-tissue envelope is critical to avoid loss of bone graft during knee range of motion.

Long-Term Results of Patellar Bone-Grafting for Severe Patellar Bone Loss During Revision Total Knee Arthroplasty

BACKGROUND

There is no consensus on managing severe patellar bone loss after total knee arthroplasty. We previously described an initial series involving a novel technique of patellar bone-grafting with a short follow-up. The purpose of this study was to determine long-term survivorship and the radiographic and clinical results of patellar bone-grafting during revision total knee arthroplasty in a larger series with an extended follow-up.

METHODS

We identified 90 patients from a single institution who underwent 93 patellar bone-grafting procedures for severe patellar bone loss from 1997 to 2014. The mean age of the patients was 70 years, and 46% of patients were female. Forty-five knees (48%) underwent first-time revisions, and 19 knees (20%) had undergone a failed attempt at patellar resurfacings. Intraoperative patellar caliper thickness increased from a mean of 7 to 25 mm after patellar bone-grafting (p < 0.01). Radiographic review determined changes in patellar height, tracking, and remodeling. Knee Society scores (KSSs) were calculated. The mean follow-up was 8 years (range, 2 to 18 years). Kaplan-Meier methods determined survivorship free of any revision and any reoperation. Cox proportional hazards analysis determined predictive factors for failure.

RESULTS

Survivorship free of patellar revision was 96% at 10 years. Survivorship free of any revision was 84% at 10 years. Survivorship free of any reoperation was 78% at 10 years. Increasing patient age was the only protective factor against further patellar revision (hazard ratio, 0.95; p < 0.01). When comparing initial radiographs with final radiographs, patellar height decreased from 22 to 19 mm (p < 0.01), 80% compared with 59% of patellae articulated centrally in the trochlea (p = 0.01), and 32% compared with 77% had remodeling over the lateral femoral condyle (p < 0.01). Anterior knee pain decreased from 51% to 27% postoperatively (p = 0.01). The mean knee flexion improved from 101° to 108° (p = 0.03). The mean KSS improved from 50 to 85 points (p < 0.01).

CONCLUSIONS

Reliable long-term clinical results can be expected with patellar bone-grafting for severe patellar bone loss during revision total knee arthroplasty. Pain, range of motion, and other reported outcomes improve despite radiographic changes to patellar height, tracking, and remodeling. This technique is a durable and reliable option when standard patellar resurfacing is not possible.

LEVEL OF EVIDENCE

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

Periprosthetic knee fractures. A review of epidemiology, risk factors, diagnosis, management and outcome

BACKGROUND AND AIM OF THE WORK

Periprosthetic knee fractures incidence is gradually raising due to aging of population and increasing of total knee arthroplasties. Management of this complication represents a challenge for the orthopaedic surgeon. Aim of the present study is to critically review the recent literature about epidemiology, risk factors, diagnosis, management and outcome of periprosthetic knee fractures.

METHODS

A systematic search of Embase, Medline and Pubmed was performed by two reviewers who selected the eligible papers favoring studies published in the last ten years. Epidemiology, risk factors, diagnostic features, clinical management and outcome of different techniques were all reviewed.

RESULTS

52 studies including reviews, meta-analysis, clinical and biomechanical studies were selected.

CONCLUSIONS

Correct clinical management requires adequate diagnosis and evaluation of risk factors. Conservative treatment is rarely indicated. Locking plate fixation, intramedullary nailing and revision arthroplasty are all valuable treatment methods. Surgical technique should be chosen considering age and functional demand, comorbidities, fracture morphology and location, bone quality and stability of the implant. Given the correct indication all surgical treatment can lead to satisfactory clinical and radiographic results despite a relevant complication rate.

Reconstruction of a deficient patella in revision total knee arthroplasty: results of a new surgical technique using transcortical wiring

This study aimed to report the results of a novel surgical technique for the reconstruction of a deficient patella during revision total knee arthroplasty (TKA). Twenty-eight patients (30 knees) with a deficient patella were treated with an onlay-type prosthesis and bone-augmenting procedure, using acrylic bone cement and transcortical wiring. The technique was indicated when the thickness of remnant patella was less than 8mm with variable amounts of the peripheral rim. Mean follow-up period was 36.6months (range, 24 to 55months).The respective mean Knee Society scores for knee and function improved from 34.2 and 23 points, preoperatively to 73.5 and 61 points, at final follow-up. One patient experienced patellar fracture 1week after surgery. There were no complications associated with implanted hardware.