Ipsilateral stress fracture of the proximal tibia after primary hybrid total hip arthroplasty.
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Absorptiometry, Photon↗
Biomedical subjects
Merrill A Ritter
Publications and source records attributed to Merrill A Ritter.
Urban legends of total knee arthroplasty.
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Arthroplasty, Replacement, Knee↗
Total hip arthroplasty with satin finish, tapered stems.
Subsidence of femoral hip prostheses with a rough surface has been associated with osteolysis and loosening. However, recent evidence has suggested that smooth-finish tapered stems may not incur these problems. An experimental monobloc satin finish, tapered femoral component was designed to subside within the cement. There were 49 femoral components implanted, and patients averaged a 1.8-mm subsidence at the prosthesis-cement interface with a follow-up of 6.76 years. There were no failures attributable to aseptic loosening at the cement-bone interface. This study supports the use of a satin finish, tapered femoral component in cemented total hip arthroplasty.
Aged↗
Predicting range of motion after revision total knee arthroplasty: clustering and log-linear regression analyses.
The purpose of this study was to determine which variables affected the range of motion following revision total knee arthroplasty. These variables included preoperative flexion, intraoperative flexion, preoperative alignment, patient demographics, type of posterior soft-tissue release, previous prosthesis type, and prosthesis type used for revision of 355 total knee arthroplasties. Clustering and log-linear regression analyses were used to determine which variables were significantly related to the postoperative flexion. The mean preoperative and postoperative flexion were 100.5 degrees and 104.6 degrees. Low preoperative (<103 degrees) and intraoperative flexion (<117 degrees), young age (<44 years), and constrained and hinged prosthesis types were associated with diminished flexion. Higher preoperative and intraoperative flexion resulted in higher postoperative flexion. When comparing the results of this study to the results of a similar study of primary total knee arthroplasties, flexion improved less following revision than following primary total knee arthroplasty.
Aged↗
Medial screws and cement: a possible mechanical augmentation in total knee arthroplasty.
The purpose of this study was to determine whether screws placed beneath the medial tibial plateau in cemented total knee arthroplasty helps prevent collapse of the medial tibia. A previous study found that the AGC all-polyethylene tibial component had a 14% rate of collapse of the medial subchondral region in the first postoperative year. Of 536 implanted AGC all-polyethylene tibial components, 20 had screws inserted beneath the medial tibial plateau. No AGC all-polyethylene tibial components with screws failed because of aseptic loosening or collapse of the medial tibial plateau. The study included 125 cemented metal-backed total knee arthroplasties with screws inserted beneath the medial tibial plateau. We also found 2 cases of collapse of the medial tibial plateau and 1 case of collapse on the lateral side. No revisions were performed. The placement of screws beneath the medial tibial plateau to fill large defects is an excellent precaution against collapse of the medial tibia.
Aged↗
The role of cemented sockets in 2004: is there one?
Cement fixation of the acetabular cup in total hip arthroplasty (THA) has evolved through multiple generations of cement technology. Whereas cement technology has produced improvements in cemented femoral fixation, the cemented socket still produces inconsistent results. Even with our current knowledge that cemented cups require exposure of cancellous bone, a clean and dry socket, and adequate bony coverage of the cup, surgeons such as myself are unable to control radiolucency at the bone-cement interface. The technical difficulty of cementing the acetabular cup has led to the increasing prevalence of cementless acetabular cups. Although cementless fixation has resulted in increased incidence of osteolysis, the surgical procedure is less technically demanding, and the long-term mechanical fixation results have been more consistent. Given the experiential learning curve that most orthopedic surgeons face with cemented fixation of the acetabular cup component, the role of the cemented socket in THA today is limited.
Acetabulum↗
Total knee arthroplasty in patients with angular varus or valgus deformities of > or = 20 degrees.
Of 8,014 surgeries between January 1986 and August 2000, 82 primary total knee arthroplasties (TKAs) were performed on 75 patients with severe preoperative varus or valgus deformity of greater than or equal to 20 degrees with a minimum 2-year follow-up time and a posterior cruciate retaining prosthesis. This study was designed to determine whether these patients (group A) could be as successful, using a Knee Society score (KSS) and alignment, as a matched control group (group B). There was no statistical difference in knee score, alignment, or revision. One revision was performed among the severely deformed. Knees that had severe angular deformities performed as well as deformity-free TKAs. Patients with excessive deformity should not be excluded from surgical correction solely based on this deformity.
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The effect of total hip arthroplasty surgical approach on gait.
This study examined the effect of the surgical approach used in total hip arthroplasty (THA) on gait mechanics six months following surgery. Quantitative gait analysis was performed on 29 subjects: 10 anterolateral (A-L) and 10 posterolateral (P-L) THA patients and nine able-bodied, velocity-matched subjects. Discriminant function analysis was used to determine the distinction of the groups with respect to sagittal plane hip range of motion, index of symmetry, trunk inclination, pelvic drop, hip abduction, and foot progression angles. The A-L group had the largest trunk inclination (3.0+/-2.4 degrees) and the smallest hip range of motion (34.0+/-7.4 degrees). Both THA groups demonstrated greater asymmetry as expressed by the smaller symmetry index (0.97+/-0.04 for A-L and 0.98+/-0.05 for the P-L) than the able-bodied group (0.99+/-0.01). The classification procedure correctly classified 89% of the control group cases, 90% of the A-L cases, and 50% of the P-L cases. These results support the conclusion that six months following surgery, the gait of the majority (85%) of THA patients has not returned to normal. The A-L patients displayed distinct gait patterns, while a small percentage (30%) of the P-L patients demonstrated normal gait. While these differences are statistically significant, the clinical significance is unknown and linked to the duration that they persist.
Aged↗
Long-term followup of posterior-cruciate-retaining TKR in patients with rheumatoid arthritis.
A consecutive series of 220 primary posterior-cruciate ligament-retaining total knee replacements were done in 148 patients with rheumatoid arthritis. From this group, 212 total knee replacements (141 patients) were followed up for an average of 10 years. Average knee scores at 5, 10, 15, and 20 years after operation improved to 86, 83, 88, and 89, respectively, and average function scores improved to 70, 72, 64, and 88, respectively. Five knees (2.4%) were revised for deep infection. Posterior instability, recurvaum, or mediolateral instability, combined or otherwise, occurred in 15% (32 knees; in 31 patients). Three tibial components (1.4%) were revised: one for suspected aseptic loosening and two for instability. Excluding infections and failed metal-backed patellas, Kaplan-Meier survival rates were 99.5%, 97.9%, and 96.5%, respectively. Favorable long-term results may be achieved with posterior-cruciate ligament-retaining total knee replacements in patients with rheumatoid arthritis. Concern remains, however, about rotational instability in certain cases associated with preoperative genu-valgum and ipsilateral planovalgus deformity.
Adult↗
Tibial component failure mechanisms in total knee arthroplasty.
The purpose of this study was to examine the failure mechanisms and factors associated with failure of a nonmodular metal backed cemented tibial component. Out of 3152 total knee replacements done for osteoarthritis, 41 tibial components had been revised (1.3%). Four distinct failure mechanisms were identified: 20 knees were revised for medial bone collapse, 13 for ligamentous imbalance, 6 for progressive radiolucencies, and 2 for pain. Factors associated with medial bone collapse were varus tibial component alignment more than 3.0 degrees , Body Mass Index higher than 33.7, and overall postoperative varus limb alignment. Ligamentous imbalance was more prevalent in knees with preoperative valgus deformity. There were no knees revised for tibial component polyethylene wear or osteolysis. We conclude that the dominant failure mechanisms for this component design are related to preoperative deformity, technical factors of component alignment, overall limb alignment, and ligamentous imbalance.
Adult↗
Minimum ten-year follow-up of a straight-stemmed, plasma-sprayed, titanium-alloy, uncemented femoral component in primary total hip arthroplasty.
BACKGROUND: The long-term results of total hip arthroplasty without cement have been reported only rarely. The purpose of the present study was to evaluate the minimum ten-year results of primary total hip arthroplasty performed with use of a proximally porous-coated, plasma-sprayed, straight-stemmed, titanium-alloy femoral component. METHODS: The clinical and radiographic results of a consecutive series of 105 total hip replacements in ninety-five patients were reviewed ten to twelve years postoperatively. The diagnosis was osteoarthritis for seventy-seven hips (73%). The clinical result was evaluated on the basis of the Harris hip score, complications, and thigh pain. A detailed radiographic analysis was performed at each follow-up visit. Kaplan-Meier analysis was performed to evaluate the survival of the femoral component. RESULTS: The average Harris hip score improved from 46 points preoperatively to 92 points postoperatively. The average pain score at the time of the most recent follow-up was 42 points, with eighty-three hips (79%) rated as pain-free. Thigh pain was identified in only two patients. All radiolucent lines were seen around the tip of the stem. All hips had some degree of femoral remodeling consistent with osseous ingrowth. No femoral component was revised, and no femoral component had evidence of loosening. Eight acetabular components were revised because of loosening and wear, and one was revised because of recurrent dislocation. One focal femoral osteolytic lesion was seen. CONCLUSIONS: This femoral component afforded durable fixation at ten to twelve years after primary total hip arthroplasty. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.
Adult↗
Total joint replacement in patients with dementia syndromes: a report of thirteen cases.
The hospital course and clinical outcomes of 14 joint replacement surgeries in 13 patients with dementia syndromes were evaluated. Eight patients were disoriented postoperatively. Complications included slow progress in physical therapy, getting out of bed unattended, aggressive behavior, pulling out an intravenous or Foley catheter, and falling out of bed. Three patients were unable to comprehend their movement restrictions, resulting in one dislocated hip from bending and twisting. Eleven of twelve joints available for follow-up were believed to be painless and functional. One patient was inactive due to fractures secondary to osteoporosis. Although complications arise from patients' disoriented status, total joint replacement relieves pain, and the patients' relatives indicated satisfaction with the results of the surgery. The family of a patient with dementia syndrome must be actively involved in all aspects of care after total joint replacement.
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Debate: simultaneous bilateral knee replacements: the outcomes justify its use.
The purpose of this paper is to assess the morbidity, mortality, and clinical outcome of simultaneous bilateral total knee arthroplasty. We reviewed 4100 simultaneous bilateral total knee replacements. The knees were subjected to two Kaplan-Meier survival analyses, with failure equal to revision for aseptic loosening and failure equal to patient death. Complications and Knee Society scores were considered. The average Knee Society knee score was 90 points 3 years postoperatively and 87 points 10 years postoperatively. The complication rates were as follows: deep infection (0.8%), superficial infection (0.3%), cardiac (6 arrhythmia, 5 congestive heart failure, 1 cardiac insufficiency, 3 complete heart block, 2 myocardial infarction and cardiac arrest, and 14 myocardial infarction only) (1.5%), intestinal ileus (0.5%), gastrointestinal ulcer (0.4%), thrombophlebitis (0.9%), cerebrovascular accident (0.3%), and urinary (1 BPH-obstruction, 4 renal failure, 2 transurethral resection of the prostate, 16 urinary tract infection, and 2 urinary retention/incontinence) (1.2%). The 10-year prosthesis survival probability was 98.3%. The 10-year patient survival probability was 78.6%. Twenty-five (1.2%) patients died within the first postoperative year. The patients who died within 1 year postoperatively were older than the rest of the group. Higher age and male gender were factors related to increased mortality. The complication rates and clinical outcomes were similar to unilateral total knee arthroplasty. With regard to death early in the postoperative course, simultaneous bilateral total knee arthroplasty may pose a greater risk to the patient than a unilateral procedure. However, the early deaths may be related to older age at the time of surgery.
Aged↗
Excisional arthroplasty for patellar loosening in total knee arthroplasty.
Four thousand two hundred eighty-seven cases of Anatomic Graduated Components total knee replacements with a cemented, single-peg, all-polyethylene patellar component were performed at our institution over the past 15 years. One hundred eighty cases of patellar component loosening were found. Eleven knees (0.3%) in 11 patients required isolated patellar component reoperation. In all cases, the patellar component was excised and not reimplanted. The average follow-up for the 11 patients was 2.2 years. Five had a complete minimum follow-up of 2 years following reoperation. Pain and function were improved. Complications included infection in 3 knees and extensor lag in 1 knee. Because of the complication rate associated with isolated patellar component excision caused by a loose patellar component, we recommend surgical removal of the patellar component only in cases of severe pain and/or prominence of the component.
Arthroplasty, Replacement, Knee↗
Total joint arthroplasty in the extremely elderly: hip and knee arthroplasty after entering the 89th year of life.
The goal of this study was to evaluate the complications and efficacy of total joint arthroplasty in the extremely elderly and compare the survival with the normal age-matched population. One hundred one joint arthroplasties (45 total knee arthroplasties [TKAs], 56 total hip arthroplasties [THAs]) were performed in 83 patients 89 years old and older. Over an average follow-up period of 2.5 years, 26 (31%) of the patients died. Three patients (3.6%) died within the first 2 months' postoperatively. The perioperative medical complication rate (excluding deaths) was 14%. Significant improvements were noted in pain scores, Harris Hip Scores, and Knee Society Scores. The survival of patients in their nineties who undergo total joint arthroplasty is at least equal to the survival of an age-matched population for 2.5 years following surgery. With careful patient selection and patient care to minimize medical complications, total joint arthroplasty can be an excellent option for patients who are age 89 and older.
Age Factors↗
Acetabular options.
Cemented acetabular options have failed anywhere between 10% and 23% over the years and have not improved with increasing cement technology. Cementless technology, however, has basically stopped the problems of prosthesis loosening; however, wear has become a major concern. With present day cement techniques, no radiolucent lines, and a compression-molded polyethylene acetabular component, there is less than a 1% failure rate. The question is, however, whether cementing is technically feasible. Even for experienced surgeons, there is at least a 10% chance of a radiolucent line. Therefore, clinicians should work to develop better bearing surfaces so that cementless technology can be used extensively.
Acetabulum↗
Genu recurvatum in total knee replacement.
Genu recurvatum deformities are unusual before total knee arthroplasty (TKA), occurring in less than 1% of patients. Because of its rarity, concern may exist regarding the recurrence of the deformity and the potential for instability after TKA. Recurvatum may be associated with a severe osseous deformity, including genu valgum, capsular or ligamentous laxity, and, rarely, neuromuscular disease. In the presence of the latter, a plantarflexion contracture of the ankle also may be present. Therefore, specific attention should be given preoperatively to evaluation of the quadriceps, hamstrings, and gastrocnemius complex. Because genu recurvatum is known to recur in patients with certain neuromuscular disorders, the etiology of the hyperextension deformity must be elucidated thoroughly before surgery. In the absence of neuromuscular disease, however, hyperextension deformities tend not to recur after TKA. Care should be taken to avoid even mild degrees of residual instability in the coronal plane at surgery because this is associated with increased extension in the postoperative period.
Arthroplasty, Replacement, Knee↗
Total knee replacement in patients with diabetes mellitus.
The purpose of the current study was to review the results of total knee replacement (TKR) in patients with diabetes mellitus and to test the hypothesis that patients with diabetes achieve inferior results after TKR. From a consecutive series of 5220 primary cemented TKRs, 363 were done in 291 patients with diabetes mellitus. Cefuoxime-impregnated cement was used routinely. The results in the study group were compared with the results in the patients without diabetes who had TKR during the same period. The followup averaged 52 months. Knee scores were higher in patients with diabetes preoperatively (47 versus 38) and postoperatively up to 7 years (80 versus 75). The average preoperative and postoperative pain scores also were higher in patients with diabetes. Four deep infections (1.2%) occurred in patients with diabetes versus 35 deep infections (0.7%) in patients without diabetes. The revision rate (including infections) was greater in patients with diabetes (3.6% versus 0.4 %). Knee and pain scores were similar in patients with insulin-dependent and noninsulin-dependent diabetes. Postoperative function scores, however, were lower in patients with insulin-dependent diabetes. In the study group, all deep infections occurred in patients with insulin-dependent diabetes.
Adult↗