Porous tantalum patellar components in revision total knee arthroplasty minimum 5-year follow-up

A Crossed Screw Patellar Reconstruction Technique for the Treatment of the Severely Deficient Scaphoid Shaped Patella in Total Knee Arthroplasty

One of the contraindications to patella resurfacing in total knee arthroplasty is a thin and severely eroded 'deficient' patella. However, such patients often present with severe patellofemoral joint arthritis, patellar lateral subluxation, and patella maltracking, which can only be treated effectively with resurfacing. While various treatments have been proposed, options remain limited. Here we introduce a method of patella reconstruction using four 2.7-mm titanium cortical screws crossing each other into the inner shell of the patella. This provides a scaffold onto which bone cement and any standard polyethylene patellar component can be fixed. Postoperatively, the patient had no anterior knee pain, no patella maltracking, and no component loosening. Advantages of this technique include minimization of extensor disruption, low costs, easy accessibility, reproducibility, and improved mechanical strength.

Tantalum as Trabecular Metal for Endosseous Implantable Applications

During the last 20 years, tantalum has known ever wider applications for the production of endosseous implantable devices in the orthopedic and dental fields. Its excellent performances are due to its capacity to stimulate new bone formation, thus improving implant integration and stable fixation. Tantalum's mechanical features can be mainly adjusted by controlling its porosity thanks to a number of versatile fabrication techniques, which allow obtaining an elastic modulus similar to that of bone tissue, thus limiting the stress-shielding effect. The present paper aims at reviewing the characteristics of tantalum as a solid and porous (trabecular) metal, with specific regard to biocompatibility and bioactivity. Principal fabrication methods and major applications are described. Moreover, the osteogenic features of porous tantalum are presented to testify its regenerative potential. It can be concluded that tantalum, especially as a porous metal, clearly possesses many advantageous characteristics for endosseous applications but it presently lacks the consolidated clinical experience of other metals such as titanium.

The Clinical Application of Porous Tantalum and Its New Development for Bone Tissue Engineering

Porous tantalum (Ta) is a promising biomaterial and has been applied in orthopedics and dentistry for nearly two decades. The high porosity and interconnected pore structure of porous Ta promise fine bone ingrowth and new bone formation within the inner space, which further guarantee rapid osteointegration and bone-implant stability in the long term. Porous Ta has high wettability and surface energy that can facilitate adherence, proliferation and mineralization of osteoblasts. Meanwhile, the low elastic modulus and high friction coefficient of porous Ta allow it to effectively avoid the stress shield effect, minimize marginal bone loss and ensure primary stability. Accordingly, the satisfactory clinical application of porous Ta-based implants or prostheses is mainly derived from its excellent biological and mechanical properties. With the advent of additive manufacturing, personalized porous Ta-based implants or prostheses have shown their clinical value in the treatment of individual patients who need specially designed implants or prosthesis. In addition, many modification methods have been introduced to enhance the bioactivity and antibacterial property of porous Ta with promising in vitro and in vivo research results. In any case, choosing suitable patients is of great importance to guarantee surgical success after porous Ta insertion.

Periprosthetic complications of the extensor mechanism of the knee

Complications of the extensor mechanism after total knee arthroplasty are uncommon and present a challenge to the surgical team. No commonly accepted classifications or treatment strategies exist since these depend on institutional, national, and healthcare-system restrictions and possibilities. The goal of this chapter is to provide an overview of existing treatment options for the different possible scenarios. These treatment options reflect the experience of the author and do not display all possibilities available.

Patellar Rebar Augmentation in Revision Total Knee Arthroplasty

BACKGROUND

In revision total knee arthroplasty, osteolysis, mechanical abrasion, and infection may leave patellar bone stock severely attenuated with cavitary and/or segmental rim deficiencies that compromise fixation of patellar implant pegs. The purpose of this study was to retrospectively review the use of cortical "rebar" screws to augment cement fixation in revision patelloplasty.

METHODS

From 2006 to 2018, dorsal patellar rebar technique was used for patellar reconstruction in 128 of 1037 revision total knee arthroplasty cases (12.3%). Follow-up was achieved with serial radiographs and prospective comparison of Knee Society Scores (KSSs) for clinical outcome. Complications and implant failures requiring reoperation or modified rehabilitation were also assessed.

RESULTS

Of the 128 patellar revisions performed using the rebar technique, 69 patients were women and 59 patients were men. The average age of the group was 69.5 years (range, 32-83 years). The mean follow-up of the cohort was 37 months (range, 13-109 months). The most common causes for revision were kinematic conflict, periprosthetic joint infection, and aseptic loosening. The median number of rebar screws used was 5 (range, 1-13). Preoperative KSSs for the study cohort averaged 50 (range, 0-90) At latest follow-up, mean KSS was 85 (range, 54-100). There were 4 patellar-related complications (3.1%) with no implant failures at study conclusion. Retrieval analysis revealed rigid fixation of the reconstructed patellar component in all cases.

CONCLUSIONS

Patellar rebar screw augmentation is a useful technique when there are significant cavitary deficiencies and limited segmental rim deficiencies. This technique allows the surgeon to extend indications for patellar revision arthroplasty.

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.

Shaped titanium wedges for subtalar distraction arthrodesis: Early clinical and radiological results

BACKGROUND

Displaced intraarticular calcaneum fractures are associated with late symptomatic hind foot malalignment and painful arthrosis for which distraction subtalar fusion might be considered. During subtalar distraction arthrodesis, a structural graft is often used to fill gaps. Autograft, the current gold standard, is limited in availabilityand is associated with donor-site morbidity and collapse. Allografts have the risk of infectious disease transmission, rejection and failure to integrate. The clinical outcomes and midterm results of subtalar distraction arthrodesis with biofoamtitanium wedges are presented.

METHODS

A review of 4 patients (3 male and 1 female) undergoing subtalar bone block distraction arthrodesis using biofoam titanium wedges is reported. Results were evaluated clinically and radiologically Mean time from trauma to surgery was 27.5 months and mean follow up was 12 months.

RESULTS

The mean FAAM ADL score improved from 31.4% preoperatively to 74.2% postoperatively and mean AOFAS score improved from 23.4 preoperatively to 69.6 postoperatively.There was improvement in all radiographic parameters, with 44% improvement in calcaneal pitch, 23% improvement in talocalcaneal angle, 21% increase in talus-first metatarsal angle, and 13.5% correction of talocalcaneal height. VAS Pain scores wasimproved from a pre-operative mean of 8 to a post-operative mean of 2. Mean time to fusion was 13 weeks. Union was achieved in all cases.

CONCLUSION

Our data suggest titanium wedges may be used as a structural graft option for subtalar bone block distraction arthrodesis. Fusion rates and time to incorporation are comparable to autogenous bone graft without the associated morbidity. Level IV Case Series.

Three-dimensional printed porous tantalum prosthesis for treating inflammation after total knee arthroplasty in one-stage surgery - a case report

Chronic inflammation and bone defects after total knee arthroplasty are a challenge for the orthopedic surgeon. There have been few reports on application of a three-dimensional (3D) printed porous tantalum prosthesis in such situations. We report an 83-year-old female patient who presented to our clinic with consistent pain of the left knee for 10 years and a severe decline in mobility for 2 years. Chronic inflammation, loosening of a tibial prosthesis with a bone defect, and severe osteoporosis were diagnosed. The patient was treated with computer designed and manufactured, personalized, 3D printed porous pure tantalum pad-assisted left total knee arthroplasty. The surgery went smoothly and the patient achieved a satisfactory recovery after surgery. A 3D printed porous tantalum prosthesis can be used to reconstruct tibial bone defects in patients with chronic inflammation after joint replacement surgeries.

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.

Ignore the Patella in Revision Total Knee Surgery: A Minimum 5-Year Follow-Up With Patella Component Retention

BACKGROUND

In the setting of aseptic revision, a common question is: what should be done with the previously resurfaced patella? We report on a series of aseptic revision total knee arthroplasties (RTKA) where one or both components were revised and the patella was not.

METHODS

The study group was 147 consecutive RTKA in 137 patients with a mean age of 70.1 ± 9.3 years where the patella was not revised. The average body mass index was 31.0 ± 5.4 kg/m². Follow-up was a minimum of 5 years (range, 5 to 12 years). At final follow-up, 13 patients died and 2 patients were lost to follow-up leaving 122 patients and 130 knees available for review. Mean time from primary surgery to RTKA was 9.2 ± 5.5 years. Both components were revised in 50 knees, the femur only in 11 knees, the tibia only in 12 knees, and 57 had an isolated polyethylene revision. We found 5 patients with a mismatch between the patella and femoral components and 30 cases with patella component wear identified intraoperatively.

RESULTS

At final follow-up, there were no reoperations on any patella and none were at risk of failure. There were 6 knees with a lateral patella tilt beyond 10°, but none were subluxed. Knee Society Scores averaged 85 ± 17.2 points at final follow-up.

CONCLUSION

At midterm follow-up in this group of RTKA where the patella was not revised, we identified no subsequent failures of the patella. This is despite the presence of mild patella polyethylene wear and mismatched shapes in several knees.

LEVEL OF EVIDENCE

III.

Patellar complications after total knee arthroplasty

Patellar complications are a source of poor total knee arthroplasty (TKA) outcomes that can require re-operation or prosthetic revision. Complications can occur with or without patellar resurfacing. The objective of this work is to answer six questions. (1) Have risk factors been identified, and can they help to prevent patellar complications? Patellar complications are associated with valgus, obesity, lateral retinacular release, and a thin patella. Selecting a prosthetic trochlea that will ensure proper patellar tracking is important. Resurfacing is an option if patellar thickness is greater than 12mm. (2) What is the best management of patellar fracture? The answer depends on two factors: (a) is the extensor apparatus disrupted? and (b) is the patellar implant loose? When either factor is present, revision surgery is needed (extensor apparatus reconstruction, prosthetic implant removal). When neither factor is present, non-operative treatment is the rule. (3) What is the best management of patellar instability? Rotational malalignment should be sought. In the event of femoral and/or tibial rotational malalignment, revision surgery should be considered. If not performed, options consist of medial patello-femoral ligament reconstruction and/or medialization tibial tuberosity osteotomy. (4) What is the best management of patellar clunk syndrome? When physiotherapy fails, arthroscopic resection can be considered. Recurrence can be treated by open resection, despite the higher risk of complications with this method. (5) What is the best management of anterior knee pain? The patient should be evaluated for causes amenable to treatment (fracture, instability, clunk, osteonecrosis, bony impingement on the prosthetic trochlea). If patellar resurfacing was performed, loosening should be considered. Otherwise, secondary resurfacing is appropriate only after convincingly ruling out other causes of pain. A painstaking evaluation is mandatory before repeat surgery for anterior knee pain: surgery is not in order in the 10% to 15% of cases that have no identifiable explanation. (6) What can be done to treat patellar defects? Available options include re-implantation (with bone grafting, cement, a biconvex implant, or a metallic frame), bone grafting without re-implantation, patellar reconstruction, patellectomy (best avoided due to the resulting loss of strength), osteotomy, and extensor apparatus allograft reconstruction. LEVEL OF EVIDENCE: V, expert opinion.

Long-Term Outcomes of Corrective Osteotomies Using Porous Titanium Wedges for Flexible Flatfoot Deformity Correction

Common corrective osteotomies used in flexible flatfoot deformity reconstruction include Cotton and Evans osteotomies, which require structural graft to maintain correction. Auto-, allo-, and xenografts are associated with a number of limitations, including disease transmission, rejection, donor site morbidity, technical challenges related to graft fashioning, and graft resorption. Porous titanium is a synthetic substance designed to address these flaws; however, few studies have been reported on the efficacy, safety, and long-term outcomes. A multicenter retrospective cohort of 63 consecutive preconfigured porous titanium wedges (PTWs) used in flexible flatfoot reconstructions from June 1, 2009 to June 30, 2015 was evaluated. The primary outcome measure was the pre- to postdeformity correction efficacy. The secondary outcomes included maintenance of correction at a minimum follow-up point of 12 months, complications, graft incorporation, and graft safety profile. Multivariate linear regression found a statistically significant improvement in all radiographic parameters from preoperatively to the final weightbearing radiographs (calcaneocuboid 18.850 ± 4.020 SE, p < .0001; Kite's, 7.810 ± 3.660 SE, p = .04; Meary's 13.910 ± 3.100 SE, p = .0001; calcaneal inclination, 5.550 ± 2.140 SE, p = .015). When restricted to patients with >4 years of follow-up data, maintenance of correction appeared robust in all 4 measurements, demonstrating a lack of bone or graft resorption. No patients were lost to follow-up, no major complications or implant explantation or migration occurred, and all implants were incorporated. Minor complications included hardware pain from plates over grafts (8%), 1 case of scar neuritis, and a 5% table incidence of transfer pain associated with the PTWs. These results support the use of PTWs for safety and degree and maintenance of correction in flatfoot reconstruction.

Radiographic Outcomes Following Lateral Column Lengthening With a Porous Titanium Wedge

BACKGROUND

Lateral column lengthening (LCL) is commonly utilized in treating stage II posterior tibialis tendon dysfunction. This study aimed to analyze the outcomes of LCL with porous titanium wedges compared to historic controls of iliac crest autograft and allograft. We hypothesized that the use of a porous titanium wedge would have radiographic improvement and union rates similar to those with the use of autograft and allograft in LCL.

METHODS

Between May 2009 and May 2014, 28 feet in 26 patients were treated with LCL using a porous titanium wedge. Of the 26 patients, 9 were males (34.6%). The average age for males was 43 years (range, 17.9-58.7), 48.7 years (range, 21-72.3) for females. Mean follow-up was 14.6 months. Radiographs were examined for correction of the flatfoot deformity and forefoot abduction. All complications were noted.

RESULTS

Radiographically, the patients had a significant deformity correction in the anteroposterior talo-first metatarsal angle, talonavicular coverage angle, lateral talo-first metatarsal angle, and calcaneal pitch. All but 1 patient (96%) had bony incorporation of the porous titanium wedge. The average preoperative visual analog scale pain score was 5; all patients but 3 (12%) had improvements in their pain score, with a mean change of 3.4.

CONCLUSION

LCL with porous titanium had low nonunion rates, improved radiographic correction, and pain relief.

LEVEL OF EVIDENCE

Level IV, case series.

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.

Minimum 6-year follow-up of revision total knee arthroplasty without patella reimplantation

Management options for the polyethylene patellar button during a revision total knee arthroplasty (TKA) include retention, revision, or removal of the button without replacement (patelloplasty). Our purpose was to determine the midterm outcome of patients undergoing revision TKA with patelloplasty. We retrospectively reviewed a single surgeon's database for patients undergoing such surgery from May 2001 to June 2005 and identified 33 (34 knees). The 25 patients (26 knees) who had at least 6 years' follow-up formed our study group. We compared preoperative and final follow-up Knee Society Scores and radiographs. Mean Knee Society Scores had increased from 50 (range, 23-88) to 93 (range, 41-100), respectively. No patient required additional surgery. We conclude that, at midterm follow-up, patelloplasty appears to be a satisfactory option in the management of the patella in revision TKA.