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Biomedical subjects

Richard D Scott

Publications and source records attributed to Richard D Scott.

At least 19 recordsLinked to original sources
PubMed2006

The effect of distal femoral resection on passive knee extension in posterior cruciate ligament-retaining total knee arthroplasty.

Full passive extension in total knee arthroplasty is predicated on creating a large enough extension gap to accommodate any given combined thickness of femoral and tibial components. Additional distal femoral resection can achieve more passive knee extension. The predictable effect of further distal femoral resection has never been studied. We designed a simple institutional review board-approved, intraoperative study to quantify this effect. Routine posterior cruciate ligament-preserving total knee arthroplasty was performed with measured femoral and tibial resections, yielding full passive extension with trial components. Distal femoral augments were then sequentially applied to the back of the femoral trial component, and passive knee extension was measured. The data show that an average value of 9 degrees of femoral contracture is corrected for every 2 mm of distal femoral resection.

Aged↗
PubMed2006

The effect of patellar thickness on intraoperative knee flexion and patellar tracking in total knee arthroplasty.

We designed a simple IRB-approved study to evaluate the intraoperative effect of patellar thickness on knee flexion and patellar tracking during total knee arthroplasty. Routine PCL-retaining total knee arthroplasty was performed in 31 consecutive knees. With clinical balance and congruent patella tracking established, custom trial patellar components that were thicker than the standard trial by 2-mm increments (2-8 mm) were sequentially placed and trialed. Passive flexion was recorded to the nearest 5 degrees with an intraoperative goniometer and gross mechanics of patellofemoral tracking were visually assessed. On average, passive knee flexion decreased 3 degrees for every 2-mm increment of patellar thickness. Furthermore, for the knee system used in this study, increased patellar thickness had no gross effect on patellar subluxation or tilt.

Aged↗
PubMed2006

Comparative flexion after rotating-platform vs fixed-bearing total knee arthroplasty.

A retrospective review of rotating-platform (n = 113) and fixed-bearing (n = 100) total knee arthroplasties at a minimum 2-year follow-up was performed. All patients in both groups in this study had osteoarthritis and underwent surgery by 1 of the 2 senior authors at 1 of 2 institutions. A cruciate-retaining total knee arthroplasty was implanted with patellar resurfacing in all cases. The only difference between the 2 groups was the design of the tibial bearing and its tibial tray. Through minimization of confounding variables relating to pathology, surgeon, institution, soft-tissue balancing, and type of prosthesis, this study isolates articular design as a variable. We could not demonstrate any significant difference in knee flexion after either fixed-bearing or rotating-platform cruciate-retaining total knee arthroplasty.

Aged↗
PubMed2006

Conversion of failed unicompartmental knee arthroplasty to TKA.

UNLABELLED: As the number of unicompartmental knee arthroplasties performed continues to rise, so too will the number of failures. In order to justify its continued use, conversion to total knee arthroplasty must be evaluated. From 1993-2004, 22 consecutive knees from 18 patients with a failed unicondylar knee arthroplasty underwent conversion to total knee arthroplasty. The most common modes of failure were polyethylene wear (12 patients), loosening of the femoral (4 patients) or tibial component (3 patients), and osteoarthritis progression (3 patients). All patients were converted to primary cruciate retaining components. Twenty-seven percent of patients had contained defects on the femoral condyle that required bone graft. No femoral stems or metal augmentation were required. Forty-five percent of patients had contained defects on the tibia that required bone graft. Metal wedge augmentation was required in five knees (23%), and stems were used in two patients. Sixteen of 22 knees (73%) were followed for an average of 64.5 months. Knee Society knee scores and functional scores at latest followup were 93 and 78, respectively. Conversion of a failed unicondylar knee arthroplasty to a total knee arthroplasty is technically demanding, but may be done successfully with careful preoperative planning and possible need for revision techniques. LEVEL OF EVIDENCE: Therapeutic study, level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2006

Unicompartmental knee arthroplasty in octogenarians: survival longer than the patient.

The unicompartmental knee arthroplasty continues to gain popularity as a viable treatment option for disease isolated to one compartment. It has been reported to provide decreased perioperative morbidity, faster recovery, and excellent long- term survival. We hypothesized that the unicompartmental knee arthroplasty is durable enough to benefit octogenarians, and may be a viable alternative to total knee arthroplasty as the definitive treatment of localized arthritis in this age group. From 1978 to 1990, 28 consecutive patients (38 knees) 80 years or older had unicompartmental knee arthroplasties. Knee Society knee and function scores improved at an average of 4 years followup (range, 2-9 years). Family members reported 90% patient satisfaction regarding expectations and desire to have the surgery again. The mean postoperative survival was 11.9 years, and only two of the 38 knees (5%) required surgical intervention. At final followup, 25 patients had died with all but one patient having the index unicompartmental knee arthroplasty in place and functioning well. Of the three living patients, one required surgery for femoral component fracture 10 years after the index procedure. The unicompartmental knee arthroplasty can be expected to provide reliable and durable results in certain octogenarians, and should be regarded as a definitive treatment option in appropriated selected patients of this age group.

Age Factors↗
PubMed2006

McKeever hemiarthroplasty of the knee in patients less than sixty years old.

BACKGROUND: Knee arthritis in the young patient is a challenging problem that may necessitate surgical treatment. We continue to perform hemiarthroplasty with a metallic tibial implant in selected young patients who, for various reasons, are not candidates for osteotomy, unicompartmental arthroplasty, or total knee arthroplasty. The purpose of the present study was to determine the minimum twelve-year results of this procedure in young patients. METHODS: The original study group consisted of a consecutive series of twenty-four patients (twenty-six knees) who were managed with McKeever tibial hemiarthroplasty for the treatment of unicompartmental osteoarthritis of the knee. All patients were younger than sixty years of age at the time of the index procedure (average age, 44.6 years). During the study period, two patients died and one was lost to follow-up, leaving twenty-one patients (twenty-three knees) available for review. All patients were followed clinically for a minimum of twelve years or until revision. Knee Society knee and functional scores and Tegner scores were determined, and seven of the ten implants were evaluated radiographically. RESULTS: Thirteen knees were revised at an average of eight years after the index procedures. All thirteen knees had an uncomplicated revision to either a unicompartmental arthroplasty or total knee arthroplasty. Ten retained implants were available for clinical review after an average duration of follow-up of 16.8 years. The mean Knee Society knee scores, functional scores, and Tegner scores, available for nine of these ten knees, were 80, 97, and 4.2, respectively. CONCLUSIONS: We believe that the McKeever tibial hemiarthroplasty continues to be a reasonable surgical option for patients who are not candidates for osteotomy and are too young or too active for a unicompartmental or total knee arthroplasty.

Adult↗
PubMed2006

Three decades of experience with unicompartmental knee arthroplasty: mistakes made and lessons learned.

Unicompartmental arthroplasty results and survivorship will continue to improve with time. The future will refine patient selection and bring better surgical techniques and prosthetic designs. Improved polyethylene will increase longevity of the arthroplasty, and mobile-bearing articulations also may improve longevity by decreasing wear and allowing a metal-backed component with relatively thin polyethylene inserts for a conservative arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2006

Surgical technique tips and pearls in rotating-platform knee arthroplasty.

Rotating-platform mobile-bearing knee arthroplasties have potential advantages over fixed-bearing knee prostheses that may lead to better long-term wear of the polyethylene articulation. Their potential disadvantages include bearing spin-out that is usually the result of a tight posterior cruciate ligament in need of release. The "slide-back test" can help determine this need during placement of the trial components. Clearing polymerized cement from the back of the knee can be difficult during rotating-platform knee arthroplasty unless cementing is completed using a trial tibial insert without a stem. Exchanging a rotating-platform insert at a future arthrotomy can be facilitated by the use of a shim that provides exposure to the polyethylene tibial post that articulates within the stem of the tibial tray. Severing the post allows extraction of the polyethylene plateau and access to the post within the tray.

Arthroplasty, Replacement, Knee↗
PubMed2005

Bony ankylosis following total knee arthroplasty: a case report.

While bony ankylosis secondary to heterotopic ossification (HO) following total hip arthroplasty (THA) is well known to produce disability in the hip, much less has been written about the development of heterotopic ossification about the knee after total knee arthroplasty (TKA). Additionally, to our knowledge, there has been no published case of complete bony ankylosis of the knee following total knee arthroplasty. We present such a case in a 53 year old male who underwent a primary total knee arthroplasty after resolution of septic arthritis.

Ankylosis↗
PubMed2005

Zone 4 femoral radiolucent lines in hybrid versus cemented total knee arthroplasties: are they clinically significant?

UNLABELLED: Aseptic loosening of the femoral component is an infrequent but important cause of failure in total knee arthroplasties. Inadequate support in the posterior femoral condylar region (radiographic Zone 4) has been associated with loosening. This zone also has been implicated as a site for ingress of wear debris particles leading to osteolysis. We determined the prevalence of Zone 4 radiolucent lines using fluoroscopy to obtain true lateral radiographs in a series of patients who had bilateral simultaneous total knee arthroplasties with a cemented femur on one side and a cementless porous ingrowth femur on the other. We hypothesized that cementless fixation would yield fewer Zone 4 radiolucent lines than cemented fixation. At an average 7.6 +/- 4.4 years followup, 11 of 16 patients (69%) with cemented femoral fixation had Zone 4 radiolucent lines, whereas none of the patients with cementless prostheses had radiolucent lines. Three of 11 radiolucent lines (27%) were progressive. Knee Society scores were similar for both groups. No femoral components in either group were clinically loose. When excellent initial stability was obtained, cementless femoral fixation yielded fewer Zone 4 radiolucent lines compared with cemented fixation. LEVEL OF EVIDENCE: Therapeutic study, Level III (retrospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2005

The Knee Society system of standardized abbreviations for surgery of the arthritic knee.

A new standardized system of abbreviations has been adopted by the Knee Society to bring clarity and brevity to scientific reports involving the arthritic knee. This system works by using a set of core abbreviations that are modified with prefixes, suffixes, and superscript notations to indicate succinctly the surgical approach, the procedure used, and the type of prosthesis implanted.

Abbreviations as Topic↗
PubMed2005

Determination of neutral tibial rotational alignment in rotating platform TKA.

UNLABELLED: Use of a fixed anatomic landmark to set rotation of the tibial component may lead to rotational malalignment. Post wear in stabilized components, backside wear in any conforming modular system, and patellar maltracking may result from tibiofemoral rotational incongruence. We aimed to quantify tibial rotational alignment in 109 primary rotating platform TKAs. After trial components were inserted with the knee properly balanced, we recorded the neutral point of the rotating tibial insert, in extension, relative to the most medial aspect of the tibial tubercle. We hypothesized that all neutral points would lie within 10 degrees of the mean. Divergence of the neutral point was recorded as being internal or external to the medial border of the tibial tubercle to the nearest 5 degrees increment. Our results showed a mean divergence of 5 degrees +/- 5 degrees external to the medial border of the tubercle. Five percent of knees, however, had neutral points > or = 10 degrees from the mean. Surgeons who use fixed-bearing modular components with any rotational constraint must be cautious in choosing a fixed anatomic tibial landmark to determine the rotational alignment of the tibial component. Doing so may create tibiofemoral rotational malalignment in full extension that may lead to suboptimal outcomes. LEVEL OF EVIDENCE: Diagnostic study, Level II-3. See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2005

Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. A study of patients followed for a minimum of fifteen years.

BACKGROUND: There have been a limited number of studies of total knee arthroplasties with durations of follow-up of fifteen years, but we are not aware of any involving modular fixed-bearing posterior cruciate-retaining prostheses. METHODS: A consecutive series of 139 total knee arthroplasties in 109 patients (average age, sixty-seven years), performed by one surgeon using a nonconforming posterior cruciate-retaining prosthesis, was followed for fifteen years or longer. Forty-five patients (fifty-nine knees) were examined at a minimum of fifteen years postoperatively, fifty-seven patients (seventy knees) had died, five patients (eight knees) were too ill to return for assessment, and two patients (two knees) were considered lost to follow-up. The patients were assessed clinically with use of the Knee Society clinical rating system, and the knees were assessed radiographically. Survivorship analysis was performed with use of worst-case-scenario analysis and with failure defined as a reoperation for any reason. RESULTS: There were five reoperations, four of which were performed because of wear of the polyethylene insert. In addition, one loose cemented femoral component was revised at fifteen years. The survival rate without revision or a need for any reoperation was 92.6% at fifteen years. The mean Knee Society score and functional score at fifteen years were 96 and 78 points, respectively. The prevalence of radiolucent lines was 13%, with 2% around the femur, 11% around the tibia, and none around the patella. None of these lines were clinically relevant. There was no evidence of progressive radiolucent lines, and there was one case of asymptomatic femoral osteolysis. CONCLUSIONS: In this single-surgeon series, modular fixed-bearing posterior cruciate-retaining total knee arthroplasties had good clinical and radiographic results with excellent survivorship for up to fifteen years. These results are comparable with those in long-term studies of posterior stabilized implants and of prostheses with mobile-bearing and nonmodular tibial inserts.

Adolescent↗
PubMed2005

Lateral unicompartmental replacement: a road less traveled.

Lateral unicompartmental replacement is performed less frequently than medial replacement and is technically more difficult. The ratio of medial to lateral arthroplasties is approximately 10:1. Differences in technique include the following: The patella is more vulnerable to impingement on the leading edge of the femoral component and must be carefully recessed. Because the wear pattern in lateral disease is more posterior than in medial disease, there often is residual cartilage on the distal femoral condyle. This is also the case when UKA is performed for the sequella of a lateral plateau fracture. To avoid this impingement, residual cartilage should probably be removed from the distal condyle before its resection and the femoral component should be undersized anteriorly. Initial tibial resection should be very conservative to avoid the need for very thick tibial components to restore alignment and stability. Err toward shifting the femoral component laterally and the tibial component medially to maximize mediolateral congruency. Consider a medial parapatellar approach (avoiding the anterior horn of the medial meniscus) to facilitate visibility and component alignment. Avoid excessive posterior tibial slope.

Arthroplasty, Replacement, Knee↗
PubMed2004

The correction of severe varus deformity in total knee arthroplasty by tibial component downsizing and resection of uncapped proximal medial bone.

The clinical and radiologic outcome of 10 patients (12 knees) with a mean varus deformity of 24 degrees (range, 20 degrees to 40 degrees ) treated with total knee arthroplasty (TKA) is presented. We describe a technique of downsizing and lateralizing the tibial component with subsequent removal of the proximal medial tibia flush with the downsized component. At a mean follow-up of 42 months (range, 12 to 64 months), the mean preoperative Knee Society and function scores had improved from 24 and 34 to 94 and 85, respectively, at follow-up. No implant has been revised. At follow-up evaluation, no evidence of osteolysis or radiographic loosening was seen and the mean tibiofemoral angle was 4 degrees of valgus. This technique provides mid-term stable correction and excellent clinical and radiographic results in patients with severe varus deformity.

Aged↗
PubMed2004

A simple capsulorrhaphy in a posterior approach for total hip arthroplasty.

In an attempt to decrease a 4% incidence of posterior hip dislocation following a posterior approach, a simple capsulorrhaphy was utilized in 255 consecutive primary total hip arthroplasties performed by 1 surgeon. All patients were reviewed at a minimum of 2 years' postoperatively, and no patient was lost to follow-up. One patient sustained a posterior hip dislocation, whereas there were no anterior hip dislocations. The dislocation rate of 0.4% is equal to or less than the rates of dislocation reported in the literature using other posterior repairs. This technique differs from other reported methods because of its simplicity and ease of repair. Only the capsule (and not the rotators) is sutured to the medius tendon (not to bone), creating an elastic endpoint that is less likely to disrupt during the healing process.

Arthritis, Rheumatoid↗
PubMed2004

Revision surgery for patellar dislocation after primary total knee arthroplasty.

This study evaluated risk factors for patellar dislocation after primary total knee arthroplasty and determined functional outcomes in patients following revision. Thirty-nine knees in 39 patients averaging 68 years (range, 27-91 years) at the time of revision were evaluated at a mean of 3.2 years (range, 2-7 years). Mean Knee Society and Function scores significantly improved from 34 and 35 to 77 and 54, respectively. Patellar dislocation most commonly resulted from errors in technique such as soft-tissue imbalance and malaligned components that led to poor tracking of the patella. Patellar tracking only improved after soft-tissue realignment in combination with revision of malaligned or loose components. Although revision significantly improved active knee extension and Knee Scores, two thirds of the patients had residual disabilities and pain.

Adult↗