Patellar resurfacing in total knee arthroplasty. A prospective, randomized, double-blind study with five to seven years of follow-up.

BACKGROUND: Whether to resurface the patella during a primary total knee arthroplasty performed for the treatment of degenerative osteoarthritis remains a controversial issue. Parameters that have been suggested as being useful in guiding this decision include patient height and weight, the presence of anterior knee pain preoperatively, and the grade of chondromalacia encountered intraoperatively. The purpose of this study was to determine whether these parameters were predictive of the clinical result following total knee arthroplasty with or without patellar resurfacing. METHODS: Eighty-six patients (118 knees) undergoing primary total knee arthroplasty for the treatment of osteoarthritis were enrolled in a prospective, randomized, double-blind study. All patients received the same posterior-cruciate-sparing total knee prosthetic components. Patients were randomized to treatment with or without resurfacing of the patella. Evaluations consisted of the determination of a Knee Society clinical score, the completion of a patient satisfaction questionnaire, specific questions relating to patellofemoral symptoms, and radiographs. Sixty-seven patients (ninety-three knees) were followed for a minimum of five years (range, sixty to eighty-four months; average, 70.5 months). RESULTS: With the numbers available, there was no significant difference between the groups treated with and without resurfacing with regard to the overall Knee Society score or the pain and function subscores. Obesity, the degree of patellar chondromalacia, and the presence of preoperative anterior knee pain did not predict postoperative clinical scores or the presence of postoperative anterior knee pain. CONCLUSIONS: The occurrence of anterior knee pain could not be predicted with any clinical or radiographic parameter studied. On the basis of these results, it seems likely that postoperative anterior knee pain is related either to the component design or to the details of the surgical technique, such as component rotation, rather than to whether or not the patella is resurfaced.

[C-reactive protein concentrations during initial (empiric) treatment of neonatal sepsis]. / Koncentracije C-reaktivnog proteina tokom pocetnog lecenja sepse kod novorodjenceta.

INTRODUCTION: Neonatal septicaemia is characterized by high mortality so that intravenous antibiotics must be administered on clinical suspicion. Initial antibiotic therapy, before the results of microbiological evaluation, is based on empirical data in regard to sensitivity of prevalent bacterial strains. In the past years, aetiological causes of neonatal sepsis have been changed with an increased bacterial resistance to the usual combination of initial antibiotics. AIM: We compared changes of serum C-reactive protein (CRP) concentrations in neonates with proven neonatal sepsis in response to initial antibiotic therapy (inappropriate or appropriate). Our hypothesis was that changes of CRP levels during the first 48 hours of treatment and before microbiologic results could be useful in evaluation of effectiveness of empiric antibiotics. METHODS: Our prospective study included all neonates with suspected sepsis referred to our Intensive Care Unit from January 1992 to December 1996. Neonates received ampicillin and gentamycin/or amikacin (during the first week of life), while infants older than 7 days of life were given combination of cloxacillin and aminoglycozides. In patients with late neonatal sepsis who also had meninigitis, cloxacillin was substituted with ampicillin. Microbiological identification was performed with routine bacteriological methods. Susceptibility of isolated bacterial strains to antibiotics was performed by Kirby-Bauer disc-diffusion method. Serum concentration of CRP was measured by immunoturbidimetry (Turbox CRP, Orion Diagnostica) and CRP concentration higher than 20 mg/l was regarded as elevated. Blood sampling for CRP measurements were taken before the treatment (CRP0), and during the first (CRP1) and second (CRP2) day of empiric therapy. The interval between sampling was from 12 to 24 hours. RESULTS: A total of 1520 neonates were evaluated during this study period and 47 patients fulfilled criteria for final analysis. In 14 of 47 patients initial antibiotic treatment was inappropriate. The most frequent resistant strains was KI. pneumoniae (6) followed with St. aureus (4), E. coli (2) and Pseudomonas (2). During initial evaluation six patients had concomitant meningitis while two had concomitant septic arthritis and two necrotizing enterocolitis, respectively. Seven (50%) of 14 patients with non-adequate initial treatment died. In 33 cases of adequately treated septicaemia the course was uncomplicated and no lethal outcome was observed. In the first group of 14 patients who received inappropriate treatment serum CRP concentations (mg/L; mean and +/- SD) were: CRP0 = 107.5 +/- 65.6; CRP1 = 155.3 +/- 75.7; CRP2 = 209.1 +/- 67.0, while in 33 repeated samples of the 33 patients in the second group who received adequate treatment the following results were recorded: CRP0 = 124.0 +/- 78.1; CRP1 = 133.8 +/- 63.5; CRP2 = 94.6 +/- 46.4. Increase in serum CRP concentration in the first group during the first 48 hours of initial non-adequate therapy was significantly higher (p = 0.015, two way ANOVA) than in the second group with appropriate treatment. During the first 24 hours of treatment increase in serum concentration of CRP was registered in 12 (85.7%) of 14 measurements in patients with non-adequate therapy and in 19 (56.7%) of 33 measurements in patients with adequate therapy. In the first group during the second day of treatment, in 11 (78.6%) of 14 cases an increase in serum CRP concentration was recorded while in 3 (14.3%) cases CRP concentration decreased. In 31 (91.2%) of 34 measurements in patients with adequate treatment CRP concentration decreased during the second day of treatment and in only 3 (8.8%) cases CRP concentration increased. With an increase in serum concentration of CRP more than 10 mg/L in the second day of antibiotic treatment, probability of non-adequate antibiotic therapy (positive predictive value) was estimated to be 77.0%. Any recorded decrease of serum CRP concentration may confirm appropriate choice of antibiotics during the second day of treatment with probability of 93.3% (negative predictive value). DISCUSSION: Measurement of serum CRP concentration is useful for diagnosis of severe neonatal sepsis. In our study all isolated bacterial strains were comparable in their ability to activate systemic inflammatory response and CRP production. It is known that serial CRP measurements during neonatal sepsis are useful in making decision to cease antibiotic treatment. The highest serum CRP concentrations were detected during the first day of illness but, in some cases even with appropriate treatment, CRP peak levels due to sustained pro-inflammatory action of interleukin-6 production could be detected even 24 hours after treatment was started. Our study showed that in patients with non-adequate initial antibiotic therapy of neonatal sepsis serum CRP concentrations increase further during the second day of treatment. By contrast, the use of appropriate antibiotic therapy in the same time period followed the significant decrease of serum CRP levels in our patients. Therefore, increase of CRP level during initial treatment, especially during the second day of treatment of neonatal sepsis should be taken as indication for replacement of initial antibiotics, even before sensitivity of microbiological causes to given antibiotics is known.

Resurfacing of the patella in total knee arthroplasty. A prospective, randomized, double-blind study.

During a two-year period, eighty-nine patients who were scheduled to have a total knee arthroplasty for the treatment of degenerative osteoarthrosis were randomly assigned to one of two groups: resurfacing of the patella or retention of the patella. All patients received the same posterior cruciate-sparing prosthesis, and all operations were performed by, or under the direct supervision of, one of us. Three patients died in the early postoperative period. The remaining eighty-six patients (118 knees; fifty-eight that had had resurfacing of the patella and sixty that had not) formed the study group. They were followed for a mean of thirty months (range, twenty-four to forty-four months). Evaluation was performed with use of the clinical scoring system of The Knee Society, a patient-satisfaction questionnaire, specific questions regarding patellofemoral symptoms and function, and radiographs. All clinical evaluations were performed by the same research nurse, without the involvement of a physician, in a blinded manner (neither the nurse nor the patient had knowledge of whether the patella had been resurfaced). Preoperatively, the mean Knee Society score, on a scale ranging from 0 to 200 points, was 89.7 points (range, 33 to 132 points); postoperatively, this score improved to a mean of 172.7 points (range, 98 to 200 points). With the numbers available for study, we could detect no significant difference between the knees that had had patellar resurfacing and those that had not with regard to the over-all score (p = 0.63), the subscore for pain (p = 0.56), or the subscore for function (p = 0.77). We also could detect no difference between the treatment groups, with the numbers available, with regard to patient satisfaction or the responses to questions involving the function of the patellofemoral joint, including the ability to exit from an automobile, to rise from a chair, and to climb stairs. Thirty-two patients had bilateral total knee replacement with resurfacing of the patella in one knee and retention of the patella in the other. These patients expressed no clear preference for either knee. Eight (13 per cent) of the sixty knees that had not had resurfacing were painful anteriorly compared with four (7 per cent) of the fifty-eight that had; this was not a significant difference (p = 0.38), with the numbers available. The anterior pain that was noted postoperatively was predominantly of new onset; it had not been observed preoperatively in three of the four knees that had had resurfacing or in four of the eight that had not. No additional treatment options were offered to the patients who had anterior pain in the knee after resurfacing. However, six (10 per cent) of the sixty knees that had not had resurfacing had it subsequently, because of anterior pain in the knee, after the twelfth postoperative month (range, fifteen to thirty-nine months). The pain decreased in four of these knees. Thus, total knee arthroplasty with retention of the patella yielded clinical results that were comparable with those after total knee arthroplasty with patellar resurfacing, but it was associated with a 10 per cent prevalence of the need for subsequent resurfacing. The prevalence of anterior pain after total knee arthroplasty was not influenced by whether or not the patella had been resurfaced. The postoperative clinical scores, the postoperative development of anterior pain, and the need for subsequent resurfacing were not predicted by the presence of preoperative anterior pain, obesity, or the grade of chondromalacia observed intraoperatively. Because of the short duration of follow-up, these results should be considered preliminary. Additional follow-up is planned.

Constituents of the endolymphatic tubules as demonstrated by three-dimensional morphometry.

The various constituents of the tubules of the human adult intraosseous endolymphatic sac were stained with lectins and Millon reaction to reveal some of the carbohydrate and protein-containing substances in the endolymph. The amount of each substance was determined by digitizing sequential temporal bone sections. Differing amounts of the various identified substances were found in sacs from patients with Meniere's disease, patients with labyrinthine fibrosis, and controls.

The in vivo performance of 250 internal fixation devices: a follow-up study.

The in vivo performance of 250 retrieved internal fixation plates was evaluated. The corrosion characteristics and metallurgical properties of each implant were assessed and correlated with respective clinical performance. Screw-plate interface corrosion and screw surface corrosion were graded; Rockwell hardness, grain size, thin inclusion content, and heavy inclusion content measurements were made. The devices studied included 169 bone plates, 59 Richards type hip screw-plates and 22 Jewett type hip nail-plates. The devices remained in situ for an average of 26.3 months, with in situ periods ranging from 1 to 192 months. The majority of the plates (50.4%) were removed due to cause-related reasons, while the remaining devices (49.6%) were removed on a routine asymptomatic basis. The primary symptomatic removal reasons consisted of implant related pain, nonunion or malunion, infection, loosening and implant breakage. Upon stereomicroscopic examination, 89% of all plates exhibited some degree of interface crevice corrosion, and 88% of all screws exhibited some degree of surface corrosion. Statistical analysis of corrosion gradings and metallurgical data revealed significant correlations between the two. As was suggested in our previous study of a limited number of implants, this study demonstrates that stricter manufacturing standards for metallurgical properties would serve to enhance corrosion resistance and improve the in vivo performance of stainless steel internal fixation devices. It is also suggested that the routine removal of all internal fixation plates after fracture healing has been achieved would reduce the occurrence of symptomatic complications, such as implant breakage, implant loosening and implant related pain.

A clinical and metallurgical analysis of retrieved Jewett and Richards hip plate devices.

The metallurgical properties of 61 retrieved 316L stainless steel (ASTM F138-76) hip plate devices used for the treatment of intertrochanteric fractures were examined. Surface and screw-plate interface corrosion characteristics were graded, and grain size, inclusion content, and hardness values were measured. These measurements were then correlated with the clinical performance of the devices. The devices studied included 21 Jewett nail-type and 40 Richards compression screw-type hip plates. The devices had been in situ an average of 26.7 months, with in situ periods ranging from 2.0 to 156.0 months. Cause-related reasons represented the majority of removals (89.8%), while only 10.2% of the hip plates were removed on a routine asymptomatic basis. The data suggest that surgeons consider this type of device as a permanent implant, with removal undertaken only for causative factors. Of all devices removed, 30.6% were retrieved from patients who presented with fracture nonunion. Upon microscopic examination, 97% of the retrieved implants exhibited some degree of either surface of interface corrosion. Statistical analysis revealed significant correlations between corrosion scores and the metallurgical properties of grain size and nonmetallic inclusion content. No statistically significant metallurgical or corrosion differences were discerned between the two types of devices studied. However, four implants of the Jewett design and four of the Richards design were found to be out of ASTM specification F-138-76. It should also be noted that four devices of the Jewett design (19%) fractured in situ, while none of the retrieved Richards designs had fractured. No correlation was observed between the plates' corrosion scores and in situ time.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and metallurgical analysis of retrieved internal fixation devices.

The clinical performance, corrosion characteristics, and metallurgical properties of 82 retrieved stainless-steel bone plates have been examined. The plates had been in situ for periods ranging from one to 169 months. Only 29% of these devices (24 of 82 plates) were removed on a routine asymptomatic basis, while 62% (51 of 82 plates) were removed for cause-related reasons such as implant-related pain, infection, nonunion or malunion, and so forth; seven plates were removed for unknown reasons. Although most patients who had plates removed for pain reported some improvement in symptoms, others felt no improvement after removal. On examination, over 89% of the recovered implants displayed some degree of either surface (pitting) or screw-plate interface (crevice and fretting) corrosion or both. Statistical analyses revealed that the metallurgical properties of grain size and nonmetallic inclusion content correlated significantly with the degree of both types of corrosion.

Retrieval and analysis of intramedullary rods. A follow-up study.

From 1980 to 1983, 16 AO intramedullary femoral rods were retrieved and analyzed clinically, radiographically, and metallurgically. Cracking and/or fracture was observed in four of the 16 specimens. All cracks occurred at the point of maximum stress at the end of the slot. In two cases a structurally weaker weld zone coincided with this location. The weld zone and slot were also found to coincide in five of the uncracked rods. Two of the four cracked rods were removed because of pain, while only three of the 12 uncracked rods caused pain. Structural and material characteristics (i.e., the location of the weld at a point of maximum stress and significant variability in microstructure), rather than surgical technique or time in situ, were found to be responsible for the implant mechanical failures. Improvements should be made in fabrication techniques and material properties. For the present, careful assessment of a painful intramedullary rod and routine removal after healing are advisable.

Retrieval and analysis of intramedullary rods.

UNLABELLED: We examined ten intramedullary rods of similar design after routine retrieval from patients. Of these ten rods, four were found to exhibit cracking around their proximal third. This behavior could not be attributed to the surgical techniques employed or to the length of time in vivo of these rods. Rather, the cracking was a function of both the metal alloy used and the method of manufacture, which occasionally allowed a weld zone to be located at the point of maximum stress with the result that cracking occurred. A change in alloy composition to a low-carbon form of 316 stainless steel probably would reduce the risk of cracking. CLINICAL RELEVANCE: In the treatment of orthopaedic disorders, it is important for the operating physician to appreciate the problems that may be encountered in using implants. One of the most important of these problems is the possibility of implant failure. The present report illustrates how a combination of both metallurgical and fabrication factors may cause such an event to occur.