Early outcomes of a modern cemented total knee arthroplasty : is tibial loosening a concern?

AIMS: Recent total knee arthroplasty (TKA) designs have featured more anatomical morphologies and shorter tibial keels. However, several reports have raised concerns about the impact of these modifications on implant longevity. The aim of this study was to report the early performance of a modern, cemented TKA design. METHODS: All patients who received a primary, cemented TKA between 2012 and 2017 with a minimum two-year follow-up were included. The implant investigated features an asymmetrical tibial baseplate and shortened keel. Patient demographic details, Knee Society Scores (KSS), component alignment, and the presence of radiolucent lines at final follow-up were recorded. Kaplan-Meier analyses were performed to estimate survivorship. RESULTS: A total of 720 of 754 primary TKAs (95.5%) were included with a mean follow-up of 3.9 years (SD 1.3); 562 (78.1%) were cruciate-retaining and 158 (21.9%) were posterior-stabilized. A total of 11 (1.5%) required reoperation for periprosthetic joint infection and seven (1.0%) for aseptic tibial loosening (five cruciate-retaining, two posterior-stabilized). Loosening occurred at a mean of 3.3 years (0.9 to 6.5). There were no cases of loosening in the 33 patients who received a 14 mm × 30 mm tibial stem extension. All-cause survivorship was 96.6% at three years (95% confidence interval (CI) 95.3% to 98.0%) and 96.2% at five years (95% CI 94.8% to 97.7%). Survivorship with revision for aseptic loosening was 99.6% at three years (95% CI 99.1% to 100.0%) and 99.1% at five years (95% CI 98.4% to 99.9%). Tibial components were in significantly more varus in those with aseptic loosening (mean 3.4° (SD 3.7°) vs 1.3° (SD 2.0°); p = 0.015). There were no other differences in demographic, radiological, or surgical characteristics between revised and non-revised TKAs for aseptic loosening (p = 0.293 to 1.00). Mean KSS improved significantly from 57.3 (SD 9.5) preoperatively to 92.6 (SD 8.9) at the final follow-up (p < 0.001). CONCLUSION: This is the largest series to date of this design of implant. At short-term follow-up, the rate of aseptic tibial loosening is not overly concerning. Further observation is required to determine if there will be an abnormal rate of loosening at mid- to long-term follow-up. Cite this article: Bone Joint J 2021;103-B(6 Supple A):51-58.

Total Knee Arthroplasty in Patients Less Than 50 Years of Age: Results at a Mean of 13 Years.

BACKGROUND: Patients between 45 and 54 years old will be the fastest-growing cohort seeking total knee arthroplasty (TKA) over the next 15 years. The purpose of this investigation is to determine the clinical outcomes of TKA in patients less than 50 years old at a minimum of 10 years. We hypothesized that this patient population would have a high rate of survivorship that is similar to that of older patients. METHODS: We reviewed 298 consecutive TKAs on 242 patients at a minimum of 10 years postoperatively. Twenty patients died and 30 TKAs were lost to follow-up leaving 248 TKAs in 202 patients (91 male, 111 female) with a mean age of 45.7 years (range, 26-49) at the time of surgery. Patient-reported outcomes, survivorship, causes of reoperation, and initial postoperative radiographic parameters were collected. RESULTS: At a mean of 13.0 years, there were 9 revisions for tibial loosening (3.6%), 8 for deep infection (3.2%), 7 for polyethylene wear (2.8%), and 3 for failed ingrowth of a cementless femoral component (1.2%). Kaplan-Meier analysis demonstrated 92.0% survivorship with failures defined as aseptic component revision and 83.9% survivorship for all-cause reoperation at 13 years. Patients with tibial alignment of 4° or more of varus or 10° or more of posterior slope were found to have increased rate of failure. CONCLUSION: While overall durability was good in this young patient population, tibial fixation and deep infection were relatively common causes of failure. In addition, increased tibial varus and slope were found to increase the rate of failure. Furthermore, the nearly 3% risk of revision for wear suggests that the use of more wear-resistant bearing surfaces may reduce the risk of failure in this patient population.

TKA patients with unsatisfying knee function show changes in neuromotor synergy pattern but not joint biomechanics.

Nearly 20% of patients who have undergone total knee arthroplasty (TKA) report persistent poor knee function. This study explores the idea that, despite similar knee joint biomechanics, the neuro-motor synergies may be different between high-functional and low-functional TKA patients. We hypothesized that (1) high-functional TKA recruit a more complex neuro-motor synergy pattern compared to low-functional TKA and (2) high-functional TKA patients demonstrate more stride-to-stride variability (flexibility) in their synergies. Gait and electromyography (EMG) data were collected during level walking for three groups of participants: (i) high-functional TKA patients (n=13); (ii) low-functional TKA patients (n=13) and (iii) non-operative controls (n=18). Synergies were extracted from EMG data using non-negative matrix factorization. Analysis of variance and Spearman correlation analyses were used to investigate between-group differences in gait and neuro-motor synergies. Results showed that synergy patterns were different among the three groups. Control subjects used 5-6 independent neural commands to execute a gait cycle. High functional TKA patients used 4-5 independent neural commands while low-functional TKA patients relied on only 2-3 independent neural commands to execute a gait cycle. Furthermore, stride-to-stride variability of muscles' response to the neural commands was reduced up to 15% in low-functional TKAs compared to the other two groups.

Heterotopic Ossification Prophylaxis After Total Hip Arthroplasty: Randomized Trial of 400 vs 700 cGy.

BACKGROUND: Heterotopic ossification (HO) is a known complication following total hip arthroplasty. Radiation is an effective prophylaxis, but an optimal protocol has yet to be determined. We performed a randomized, double-blinded clinical trial in high-risk patients to determine the efficacy of 400 vs 700 cGy doses of radiation. METHODS: One hundred forty-seven patients undergoing total hip arthroplasty and at high risk for HO at an urban medical center were randomized to receive either a single 400 or 700 cGy dose of radiation postoperatively. High risk was defined as a diagnosis of diffuse idiopathic skeletal hyperostosis, hypertrophic osteoarthritis, ankylosing spondylitis, or history of previous HO. Radiation was administered on the first or second postoperative day. A single blinded reviewer graded radiographs taken immediately postoperatively and at a minimum of 6 months postoperatively using the Brooker classification. Progression was defined as an increase in Brooker classification. Operative data including surgical approach, implant fixation, revision surgery, and postoperative range of motion data were also collected. RESULTS: A significantly greater portion of patients who received the 400 cGy dose demonstrated progression of HO than patients who received the 700 cGy dose. There were no wound complications. No preoperative factors were associated with a higher rate of progression. Patients who progressed had less flexion on physical examination than patients who did not progress, but this was not clinically significant. CONCLUSION: Seven hundred centigray was superior to 400 cGy in preventing HO formation following total hip arthroplasty in high-risk patients and may be the more effective treatment in this population. Further studies comparing 700 cGy to dosages between 400 and 700 cGy may help to clarify if a more optimal dose can be identified.

Surgical Anatomy of the Knee A Review of Common Open Approaches.

Knee-related complaints are among the most commonly encountered conditions by orthopaedic surgeons. Knee pathology varies widely and includes arthritis, deformities, fractures, infections, neuromuscular disorders, oncologic diseases, and soft-tissue injury. While nonoperative treatment modalities (activity modification, medications, injections, and physical therapy) are typically used as primary interventions, surgical treatment may ultimately become necessary. The purpose of this review is to discuss the most common open approaches to the knee, with an emphasis on surgically relevant anatomy for each approach. Understanding of the anatomy of the knee joint and associated neurovascular structures is necessary in order to avoid intraoperative complications and optimize postoperative recovery.

Preventing Leg Length Discrepancy and Instability After Total Hip Arthroplasty.

Restoration of equal leg lengths and dynamic hip stability are essential elements of a successful total hip arthroplasty. A careful clinical examination, a preoperative plan, and appropriate intraoperative techniques are necessary to achieve these goals. Preoperative identification of patients at risk for residual leg length discrepancy allows surgeons to adjust the surgical approach and/or the type of implant and provide better preoperative patient education. The use of larger femoral heads, high-offset stem options, and enhanced soft-tissue repairs have improved impingement-free range of motion as well as dynamic hip stability and have contributed to an overall reduction in dislocation. Methods for accurate leg length restoration and component positioning include anatomic landmarks, intraoperative radiographs, intraoperative calipers, stability testing, and computer-assisted surgery. If recurrent instability occurs after total hip arthroplasty, the underlying cause for dislocation should be identified and treated; this may include the use of semiconstrained dual-mobility or fully constrained liners, depending on abductor function. Surgeons should be aware of the clinical and surgical techniques for achieving leg length equalization and dynamic hip stability in total hip arthroplasty.

Does Hip Arthroscopy Affect the Outcomes of a Subsequent Total Hip Arthroplasty?

BACKGROUND: Hip arthroscopy utilization is on the rise in the United States. Thus, determining the impact of prior hip arthroscopy on subsequent total hip arthroplasty (THA) is important to understand. METHODS: A retrospective review of a high-volume orthopedic surgery practice's billing database yielded 42 hip arthroscopies that underwent subsequent THA. An age-, sex-, and body mass index (2:1)-matched cohort of primary THAs was used for comparison. RESULTS: No difference was observed in the postoperative Harris Hip Score between groups (92.1 ± 10.9 vs 90.1 ± 6.6, P = .20); however, there was greater overall improvement in Harris Hip Score in the control group (40.4 ± 18.4 vs 45.1 ± 8.7, P = .05). There were no differences observed in the complication (P = .5) or revision rates (P = .4). CONCLUSION: With the numbers available, prior hip arthroscopy does not appear to have an impact on the functional outcomes of a subsequent THA.

Repair of Intraoperative Injury to the Medial Collateral Ligament During Primary Total Knee Arthroplasty.

BACKGROUND: Optimal treatment for intraoperative injury to the medial collateral ligament (MCL) during primary total knee arthroplasty remains controversial. While some advocate primary ligament repair and a period of bracing, others suggest conversion to a knee prosthesis with increased intrinsic constraint. The purpose of this study was to characterize the outcomes of primary repair followed by bracing. METHODS: We performed a retrospective review of consecutive primary total knee arthroplasties to identify patients with intraoperative MCL laceration or avulsion treated with primary repair. Midsubstance lacerations were treated with end-to-end suture repair, whereas a screw-and-washer construct, suture, and/or suture anchors were used for reattachment of avulsions. All patients were instructed to wear an unlocked hinged knee brace for six weeks postoperatively. Patients were evaluated at a minimum of two years postoperatively for evidence of instability or other modes of failure and complications. RESULTS: An intraoperative MCL injury occurred during forty-eight (1.2%) of the 3922 total knee arthroplasties that had been performed. One patient died less than two years postoperatively, one was lost to follow-up, and one underwent an intraoperative conversion to a constrained total knee arthroplasty, leaving forty-five total knee arthroplasties available for study. There were twenty-four midsubstance lacerations and twenty-one avulsions; thirty-five of these injuries occurred during a cruciate-retaining total knee arthroplasty and ten, during a posterior-stabilized total knee arthroplasty. At a mean of ninety-nine months (range, twenty-four to 214 months), there were no symptoms or physical examination findings of instability. The mean Hospital for Special Surgery knee score increased from 47 preoperatively to 85 at the time of follow-up (p < 0.001). Five knees required intervention for stiffness (four manipulations and one revision), and two required revision for aseptic loosening. CONCLUSIONS: Our results suggest that intraoperative MCL injury can be treated with primary repair followed by hinged knee bracing without the need for increased prosthetic constraint. Stiffness, however, was a common complication.

The simple unicondylar knee: extramedullary technique.

Unicompartmental knee arthroplasty (UKA) is a successful procedure that is gaining popularity in the United States. Outcomes of UKA depend on careful patient selection as well a meticulous surgical technique and avoiding overcorrection of the preoperative deformity. Intramedullary and extramedullary (EM) cutting guides are available for most commercial systems. EM techniques avoid cannulating the medullary canals of the femur or tibia, thus diminishing the chances of marrow emboli and bleeding from the canal during the procedure. Both with accurate cuts high levels of success with precise component alignment can be achieved when using EM techniques for UKA.

Modified hybrid stem fixation in revision TKA is durable at 2 to 10 years.

BACKGROUND: Hybrid revision knee component fixation, in which cement is placed in the metaphysis combined with a cementless diaphyseal engaging stem, provides ease of insertion, possibly improved component alignment, and easier removal if required, compared with fully cemented prostheses. The literature suggests the technique has a 2 to 5 year survivorship ranging from 81% to 94%. QUESTIONS/PURPOSES: To confirm the literature we asked whether (1) a modified hybrid fixation technique is durable and reliable at an average 5-year followup, (2) this method of fixation provides clinical improvements as assessed by knee scores, (3) there are radiographic findings unique to this fixation technique, (4) the degree of knee constraint influences clinical performance or radiographic findings, and (5) end-of-stem pain is associated with this fixation method? PATIENTS AND METHODS: We retrospectively reviewed all 83 patients who had 88 both-component revision TKAs using our modified hybrid fixation technique. We assessed the Knee Society scores and evaluated radiographs for radiolucent and radiosclerotic lines. The minimum followup was 24 months (average, 65 months; range, 24-126 months). RESULTS: Kaplan-Meier survivorship free of aseptic loosening was 100% at 5 years and 90% at 10 years. Postoperatively, the mean Knee Society pain and function scores both improved. Partial radiolucent lines were rare; two components were loose. We commonly observed radiosclerotic lines adjacent to stem extensions but these did not affect clinical scores or implant stability at last followup. Neither knee scores nor radiographic findings differed based on knee constraint. End-of-stem pain occurred rarely and was transient. CONCLUSIONS: Modified hybrid fixation of revision knee arthroplasty using a diaphyseal engaging stem and cementation only in the metaphysis is durable at a mean 5 years followup. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Posterior cruciate ligament-retaining total knee arthroplasty in patients with rheumatoid arthritis: a concise follow-up of a previous report.

7We previously reported the minimum eight-year follow-up results of cruciate-retaining total knee arthroplasty in a consecutive series of seventy-two knees in patients with rheumatoid arthritis. In the present study, we evaluated the longer-term outcomes after twenty to twenty-five years of follow-up. Since the publication of our original study, ten knees have been revised: three because of periprosthetic fracture, three because of infection, two because of patellofemoral failure, and two because of posterior instability. The rate of implant survival at twenty years after surgery was 69% (95% confidence interval [CI], 56% to 79%) with revision for any reason as the end point, 81% (95% CI, 69% to 89%) with femoral or tibial component revision for any reason as the end point, and 93% (95% CI, 83% to 97%) with posterior instability as the end point. These long-term results demonstrate that posterior cruciate ligament insufficiency with instability was rarely the cause of failure following cruciate-retaining total knee arthroplasty in patients with rheumatoid arthritis.

A novel method for prevention of intraoperative fracture in cementless hip arthroplasty: vibration analysis during femoral component insertion.

Emerging minimally invasive surgery (MIS) techniques in hip arthroplasty heralded an increase in intraoperative femoral periprosthetic fractures, likely due to diminished visibility, auditory, and tactile feedback. This study attempts to identify a method to supplement the surgeon's tactile and auditory senses by analyzing vibration characteristics during femoral component impaction. A cementless femoral component was instrumented with accelerometers and a piezoelectric (PZT) patch. Data was obtained during implant impaction into replicate femurs. Acceleration measurements were obtained and signal processing techniques were applied. Metrics were analyzed from PZT excitation data. The two most correlative indices are the frequency of the anti-resonance in the 10.5 to 12 kHz band and the peak magnitude in the 9 to 11 kHz band. Both demonstrate good convergence as the prosthesis is inserted. Impact test data revealed the sum of the acceleration divided by the sum of the impact force demonstrates good convergence with implant insertion. This pattern of convergence indicates these two indices may demonstrate the ability to accurately predict optimal implant seating. This methodology is promising and has the potential to enable intraoperative determination of maximal femoral component seating and provide the surgeon valuable information to potentially prevent intraoperative fractures.

Revision total knee arthroplasty for stiffness.

Few studies have evaluated the results of revision of well-fixed components for stiffness, and some authors have recommended against this intervention based on poor reported results. Thirty-five consecutive patients underwent revision of both femoral and tibial components for stiffness. At a mean of 54.5 months (range, 25-134), the mean arc of motion improved by 44.5 degrees from a preoperative mean of 53.6 degrees to a postoperative mean of 98.1 degrees (P < .0001). The arc of motion improved by more than 30 degrees in 75% (24/32) of patients evaluated at a minimum of 2 years. Seventeen (49%) of the 35 patients required a further intervention for stiffness or sustained a complication. These results suggest that revision total knee arthroplasty for stiffness can be performed with a reasonable expectation of improvement, although the risk of complications and additional operative procedures is substantial.

Cruciate-retaining TKA using a third-generation system with a four-pegged tibial component: a minimum 10-year followup note.

BACKGROUND: A third-generation TKA system was designed to address problems encountered with earlier designs including a high rate of patellofemoral complications. At a minimum of 5 years, we previously reported survivorship of 98.7% using revision for any reason as the endpoint for a cohort that includes the patients described in this report. That cohort was unique in that a tibial component that uses four short pegs for fixation was used in a subset of patients undergoing cruciate-retaining TKA and the tibial and femoral components were precoated with polymethylmethacrylate. QUESTIONS/PURPOSES: We now report the survival rate, postoperative function, complications, radiographic loosening, and osteolysis at a minimum of 10 years postoperatively. PATIENTS AND METHODS: We retrospectively reviewed 161 patients who underwent 179 TKAs. The patella was resurfaced in all cases and all components were cemented. Patients were evaluated clinically and radiographically for evidence of component loosening and osteolysis. Forty of the 161 patients (with 44 TKAs) had died and eight patients (nine knees) were lost to followup. For the remaining 113 patients (126 knees), the minimum followup was 10 years (mean, 11.7 years; range, 10.0-13.9 years). RESULTS: Survivorship at a minimum of 10 years postoperatively using revision for any reason and revision for aseptic loosening were 97.7% and 100%, respectively. Three knees were revised: one for infection, one for periprosthetic fracture, and one for postoperative arthrofibrosis. There were no reoperations for patellar component maltracking, wear or loosening, tibiofemoral polyethylene wear, osteolysis, or aseptic loosening. Hospital for Special Surgery scores improved from a mean of 47.7 (range, 23-78) preoperatively to 85.4 (range, 33-100). CONCLUSIONS: This cruciate-retaining design had a low risk of implant failure or revision and the design changes eliminated the patellar failures seen with earlier iterations at up to 10 years. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Primary total hip arthroplasty with a porous-coated acetabular component. A concise follow-up, at a minimum of twenty years, of previous reports.

We previously reported the seven and fifteen-year results of the use of a porous-coated acetabular metal shell inserted without cement in a consecutive series of 204 primary total hip arthroplasties. In the present study, we evaluated the longer-term outcomes of these arthroplasties at a minimum follow-up time of twenty years. One hundred and fourteen (92%) of the 124 hips available for study had retained the original acetabular metal shell. A total of five acetabular components had been revised for aseptic loosening or had radiographic evidence of definite loosening. Fourteen hips with well-fixed acetabular shells required a change of the modular acetabular liner because of excessive wear and/or for the treatment of osteolysis, and liner changes have been recommended for another eight hips. The twenty-year rate of survival of the metal shell, with failure defined as revision because of loosening or radiographic evidence of loosening, was 96% (95% confidence interval, 94% to 98%). Cementless acetabular reconstruction continues to provide durable fixation at twenty years postoperatively. Wear-related complications continue to be the major mode of failure.

Revision of the acetabulum with a contemporary cementless component.

We evaluated the performance of a contemporary cementless acetabular component at a minimum of 5 years postoperatively. One hundred eighty-seven consecutive acetabular component revisions were performed using a hemispherical porous-coated component. Patients were followed prospectively with radiographs and Harris hip scores. Twenty patients died, leaving 158 patients (166 hips) available for follow-up at a mean of 91 months. No patients were lost. Eleven acetabular components (7%) required repeated revision, including 4 (2%) for aseptic loosening. Seven of the 145 unrevised acetabular components with radiographic follow-up (5%) were loose. The results of acetabular revision with this contemporary acetabular component were good but inferior to those of earlier-generation implants. This difference is likely multifactorial.

Revision of the acetabular component without cement. A concise follow-up, at twenty to twenty-four years, of a previous report.

We previously reported the results of the use of a cementless acetabular shell for revision total hip arthroplasty in 138 hips at a minimum of three, seven, and fifteen years postoperatively. The current report presents the long-term outcomes of this group at a minimum follow-up of twenty years. Since the last report, two additional hips required repeat revision, both for infection; no additional acetabular shell was loose. In the entire series to date, repeat acetabular revision was performed in twenty-one (15%) of the original 138 hips. Twenty of the twenty-one shells were well fixed at the time of repeat revision, and one had become aseptically loose. The most common reasons for repeat revision were infection (eight hips) and recurrent instability (eight hips). In the metal shells that were well fixed, an isolated liner change for polyethylene wear and/or osteolysis was performed in a total of six hips; four of these liner exchanges were performed since the time of our last report. A liner change had been recommended because of severe wear in four additional hips; thus, 18% of the fifty-six unrevised metal shells were associated with polyethylene wear-related problems. Survivorship, with revision of the shell for aseptic loosening or radiographic evidence of loosening as the end point, was 95% at twenty years (95% confidence interval, 83% to 98%). Reoperations for wear and osteolysis were first seen at approximately twelve years postoperatively. At the time of the present long-term follow-up, the reoperation rate for polyethylene wear and/or osteolysis had increased. We continue to use a hemispherical, titanium metal shell with multiple screws for fixation in the majority of acetabular revisions.

Preoperative testing for sepsis before revision total knee arthroplasty.

One hundred five consecutive painful knee arthroplasties were evaluated by a single surgeon for the presence of infection using a uniform protocol that included an erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), perioperative aspiration with synovial fluid white blood cell (WBC) count and differential, intraoperative frozen section analysis, and culture. A synovial fluid WBC count of greater than 3000 was the most precise test with a sensitivity of 100%, specificity of 98%, and accuracy of 99%. The preoperative use of an ESR and CRP proved to be an excellent screening modality with only one infection identified with both values being normal. A rational approach to perioperative testing for sepsis includes a screening ESR and CRP, and if elevated, aspiration with synovial fluid WBC count or an intraoperative frozen section.