Clinical and objective gait outcomes remained stable seven years after total knee arthroplasty: A prospective longitudinal study of 28 patients

BACKGROUND

There is a paucity of data on mid to long-term gait outcomes after total knee arthroplasty. The aims of this longitudinal study were: to assess the evolution of both clinical and gait outcomes before and up to seven years after primary total knee arthroplasty (TKA) in a cohort of patients with knee osteoarthritis.

METHODS

This study included 28 patients evaluated before and up to seven years after primary TKA with both gait analysis and patient reported outcomes; of these, 20 patients were evaluated one year after surgery as well. Kinematic outcomes during gait (gait velocity, dimensionless gait veolicity, maximal knee flexion and knee range of motion), pain relief, Western Ontario and MacMaster Osteoarthritis Index (WOMAC), quality of life and patient satisfaction were assessed and compared at each visit with the paired Wilcoxon signed rank test (p < 0.05).

RESULTS

The significant improvement achieved at one year after TKA was stable up to seven years after surgery, with all clinical and kinematic outcomes unchanged, except for gait velocity, with a significant decrease over time (1.3 (1.1-1.4) m/s one year after TKA versus 1.0 (0.9-1.1) m/s, p < 0.05 up to seven years after).

CONCLUSION

Patients with knee osteoarthritis significantly improve their clinical and kinematic outcomes at one year postoperatively and maintain the gain up to seven years after primary TKA, except for gait velocity which decreases over time, most likely along with ageing.

History of previous surgery is associated with higher risk of revision after primary total knee arthroplasty: a cohort study from the Geneva Arthroplasty Registry

Background and purpose - Prior to primary total knee arthroplasty (pTKA), 6-34% of patients have undergone surgical procedure(s) of their knee. We investigated whether history of previous surgeries influences the risk of revision of pTKA, the risk according to the type of previous surgery, and how previous surgery influences specific causes of revision and the time of revision.Patients and methods - This is a prospective cohort study from the Geneva Arthroplasty Registry. All pTKA between 2000 and 2016 were included and followed until December 31, 2019. Outcomes were risk of revision, evaluated using Kaplan-Meier survival and Cox and competing risks regression, the specific causes, and time of revision.Results - Of 3,945 pTKA included (mean age 71 years, 68% women), 21% had a history of previous surgery, with 8.3% revisions vs. 4.3%, at 3-20 years' follow-up (mean 8.6). 5- and 10-year cumulative failure by previous surgery (yes vs. no) were 6.6% (95% CI 5.1-8.5) vs. 3.3% (CI 2.7-4.0), and 8.4% (CI 6.6-10.6) vs. 4.5% (CI 3.8-5.4). Baseline differences explained only part of the higher risk (adjusted HR 1.5, CI 1.1-2.1). The risk of failure was higher for all causes of revision considered. Patients in the previous surgery group had a higher risk of an early revision.Interpretation - A history of previous surgery adversely affected the outcome with a 1.5 times higher cumulative risk of all-cause revision over the course of up to 20 years after index surgery. The increased risk was seen for all causes of revision and was highest in the first years.

Gait Analysis 1 Year after Primary TKA: No Difference between Gap Balancing and Measured Resection Technique

Mechanical alignment in total knee arthroplasty (TKA) can be achieved using dependent bone cuts. The hypothesis is that patients have a better balanced TKA, as a result. The aim of this study was to determine if this technique is superior to an independent bone cut technique in terms of gait parameters, patient-reported outcome measures (PROMs), and satisfaction assessed before surgery and at 1-year follow-up. A total of 58 patients were evaluated before and 1 year following TKA, using the Press Fit Condylar (PFC) Sigma posterior stabilizer (PS) design; 39 (70 ± 8 years; 27 women) with independent bone cuts and 19 (71 ± 7 years; 12 women) with dependent bone cuts using the Specialist TRAM. Gait was evaluated with a three-dimensional motion analysis system for spatiotemporal and kinematics parameters. Pain and functional levels were assessed using the Western Ontario and McMaster Universities arthritis index (WOMAC); general health was assessed by the short form (SF)-12. Global satisfaction, as well as patient satisfaction, related to pain and functional levels were assessed using a five-point Likert's scale. No significant difference was found between both groups in terms of age, body mass index, pain, and functional levels at baseline. At 1-year follow-up, despite an overall improvement in gait, WOMAC, SF-12 physical score and pain, none of the patients showed gait parameters comparable to a healthy control group. No surgical technique effect was observed on gait, clinical outcomes, and satisfaction level. While observing an overall improvement at 1-year follow-up, we did not find any significant difference between the two surgical techniques in terms of gait parameters, patients' outcomes, and satisfaction.

Walking Speed and Maximal Knee Flexion During Gait After Total Knee Arthroplasty: Minimal Clinically Important Improvement Is Not Determinable; Patient Acceptable Symptom State Is Potentially Useful

BACKGROUND

Total knee arthroplasty (TKA) is the operation of choice in patients with end-stage knee osteoarthritis (OA). Up to 1 in 5 patients still encounter functional limitations after TKA, partly explaining patient dissatisfaction. Which gait ability to target after TKA remains unclear. To determine whether Minimal Clinical Important Improvement (MCII) or Patient Acceptable Symptom State (PASS) values could be derived from gait parameters recorded in patients with TKA. And, if so, to define those values.

METHODS

In this ancillary study, we retrospectively analyzed gait parameters of patients scheduled for a unilateral TKA between 2011 and 2013. We investigated MCII and PASS values for walking speed and maximal knee flexion using anchor-based methods: 5 anchoring questions based on perceived body function and patients' satisfaction.

RESULTS

Over the study period, 79 patients performed a clinical gait analysis the week before and 1 year after surgery, and were included in the present study. All clinical and gait parameters improved 1 year after TKA. Nevertheless, changes in gait outcomes were not associated with perceived body function or patients' satisfaction, precluding any MCII estimation in gait parameters. PASS values, however, could be determined as 1.2 m/s for walking speed and 50° for maximal knee flexion.

CONCLUSION

In this study, we found that MCII and PASS values are not necessarily determinable for gait parameters after TKA in patients with end-stage OA. Using anchor questions based on perceived body function and patient's satisfaction, MCII could not be defined while PASS values were potentially useful.

LEVEL OF EVIDENCE

Level III.

Associations between gait analysis parameters and patient satisfaction one year following primary total knee arthroplasty

BACKGROUND

The purpose of this prospective study was to understand the relation between gait outcomes and patient satisfaction one year after total knee arthroplasty (TKA).

METHODS

Seventy-nine patients were evaluated before and one year after TKA using clinical gait analysis. Specific gait outcomes were analyzed: gait speed, stance phase, range of motion (ROM) knee flexion and maximal knee flexion. The parameters of interest selected for the statistical analysis were: gait speed and maximal knee flexion during gait. The Western Ontario and MacMaster Osteoarthritis Index (WOMAC) and patient satisfaction were also assessed. The satisfaction was evaluated using a questionnaire and was splited in five categories: very unsatisfied, unsatisfied, neutral, satisfied or very satisfied. To assess associations between patient satisfaction and maximal knee flexion during gait and gait speed, an unadjusted ordinal logistic regression analysis was used. The analysis was then adjusted for covariates: age and Body Mass Index (BMI) before surgery and WOMAC pain one year after surgery.

RESULTS

All gait outcomes after TKA had significantly improved. The ordinal logistic regression analysis found significant associations between patient satisfaction and maximal knee flexion after TKA (unadjusted and adjusted) but not for gait speed.

CONCLUSION

These findings show that all patients improved their gait outcomes one year after TKA but only a higher maximal knee flexion during gait may influence the level of patient satisfaction.

Total knee arthroplasty in achondroplasia without deformity correction: A case report with 11 years' follow-up

Knee osteoarthritis in patients with achondroplasia is rare. Bowleg deformity is typical but corrective surgery is limited. Thus, primary total knee arthroplasty (TKA) might be challenging due to the particular anatomy. We report on a patient with 11 year's follow-up after a TKA performed maintaining bowleg alignment, using a posterior stabilized, fixed-bearing design. Sequential X-rays showed radiolucencies on the femoral component within two years postoperatively, slightly increasing over time but stable at last follow-up. The Oxford Knee Score showed an excellent result at 11 years. Despite the peculiarities of a case report, TKA without concomitant osteotomies might be an option for such patients. Nevertheless, a thorough discussion about pros and cons is paramount.

The impact of body-mass index on the frontal knee alignment estimation using three-dimensional reconstruction based on movement analysis

BACKGROUND

We evaluated the influence of the body-mass index (BMI) on the estimation of the static frontal knee alignment (FKA) using three-dimensional (3D) reconstruction method based on movement analysis.

METHODS

Two-hundred nineteen knees (120 individuals with end-stage osteoarthritis) were analyzed. The validity of the 3D method was evaluated under comparison with a reference method based on weight bearing full-leg length radiography. Extensive statistical analyses (Pearson's correlation, one-way ANOVA, linear regression, boxplot diagram) over four groups of BMI (normal, overweight, obese class I and obese classes II and III) were performed.

RESULTS

For BMI below 25 kg/m², the validity of the 3D method was confirmed. For BMI over 25 kg/m², there was an increasing error of the 3D method, especially for the obese groups affected with a large varus alignment.

CONCLUSIONS

In a biomechanical context of movement analysis, the results of the study suggest that the 3D method may represent a satisfying alternative to the full-leg radiograph method with limitations regarding to BMI over 25 kg/m².

Influence of Body Mass Index on Sagittal Knee Range of Motion and Gait Speed Recovery 1-Year After Total Knee Arthroplasty

BACKGROUND

The purpose of this prospective study was to investigate the influence of body mass index (BMI) on gait parameters preoperatively and 1 year after total knee arthroplasty (TKA).

METHODS

Seventy-nine patients were evaluated before and 1 year after TKA using clinical gait analysis. The gait velocity, the knee range of motion (ROM) during gait, their gains (difference between baseline and 1 year after TKA), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), quality of life, and patient satisfaction were assessed. Nonobese (BMI <30 kg/m²) and obese patients (BMI ≥30 kg/m²) were compared. Healthy controls were also assessed. Univariate and multivariate linear regression analyses were used to assess the association between gait speed and ROM gains. Adjustment was performed for gender, age, and WOMAC pain improvement.

RESULTS

At baseline, gait velocity and knee ROM were significantly lower in obese compared with those in the nonobese patients (0.99 ± 0.27 m/s vs 1.11 ± 0.18 m/s; effect size, 0.53; P = .021; and ROM, 41.33° ± 9.6° vs 46.05° ± 8.39°; effect size, 0.52; P = .022). Univariate and multivariate linear regressions did not show any significant relation between gait speed gain or knee ROM gain and BMI. At baseline, obese patients were more symptomatic than nonobese (WOMAC pain: 36.1 ± 14.0 vs 50.4 ± 16.9; effect size, 0.9; P < .001), and their improvement was significantly higher (WOMAC pain gain, 44.5 vs 32.3; effect size, 0.59; P = .011).

CONCLUSION

These findings show that all patients improved biomechanically and clinically, regardless of their BMI.

Body mass and weight thresholds for increased prosthetic joint infection rates after primary total joint arthroplasty

BACKGROUND AND PURPOSE

Obesity increases the risk of deep infection after total joint arthroplasty (TJA). Our objective was to determine whether there may be body mass index (BMI) and weight thresholds indicating a higher prosthetic joint infection rate.

PATIENTS AND METHODS

We included all 9,061 primary hip and knee arthroplasties (mean age 70 years, 61% women) performed between March 1996 and December 2013 where the patient had received intravenous cefuroxime (1.5 g) perioperatively. The main exposures of interest were BMI (5 categories: < 24.9, 25-29.9, 30-34.9, 35-39.9, and ≥ 40) and weight (5 categories: < 60, 60-79, 80-99, 100-119, and ≥ 120 kg). Numbers of TJAs according to BMI categories (lowest to highest) were as follows: 2,956, 3,350, 1,908, 633, and 214, respectively. The main outcome was prosthetic joint infection. The mean follow-up time was 6.5 years (0.5-18 years).

RESULTS

111 prosthetic joint infections were observed: 68 postoperative, 16 hematogenous, and 27 of undetermined cause. Incidence rates were similar in the first 3 BMI categories (< 35), but they were twice as high with BMI 35-39.9 (adjusted HR = 2.1, 95% CI: 1.1-4.3) and 4 times higher with BMI ≥ 40 (adjusted HR = 4.2, 95% CI: 1.8-9.7). Weight ≥ 100 kg was identified as threshold for a significant increase in infection from the early postoperative period onward (adjusted HR = 2.1, 95% CI: 1.3-3.6).

INTERPRETATION

BMI ≥ 35 or weight ≥ 100 kg may serve as a cutoff for higher perioperative dosage of antibiotics.

[Community-acquired bacterial septic arthritis in adults: diagnosis and treatment]

The diagnosis of acute native joint bacterial infection can be difficult, because of its non- specific clinical and biological manifestation. Its management is often an emergency. Following a joint puncture, early joint lavage is performed, either by surgical drainage or by repeated arthrocentesis; and accompanied by systemic antibiotics, of which the ideal duration and route of administration remains unknown. The postoperative care is characterized by joint mobilization to avoid joint stiffening.

No regeneration of the human acetabular labrum after excision to bone

BACKGROUND

Treatment options for a symptomatic, torn, irreparable, or completely ossified acetabular labrum are limited to either excision and/or reconstruction with grafts. In a previous animal model, regeneration of the acetabular labrum after excision to the bony rim has been shown. In humans, less is known about the potential of regeneration of the labrum. Recent studies seem to confirm labral regrowth, but it is still unclear if wide excision might be a surgical option in cases where repair is not possible.

QUESTIONS/PURPOSES

The purposes of this study were (1) to determine the extent of acetabular labrum regeneration after excision to the bony rim; and (2) to determine whether this procedure results in higher hip scores.

METHODS

We reviewed all patients treated with surgical dislocation for symptomatic femoroacetabular impingement by a single surgeon at one institution between 2003 and 2008, of whom 14 underwent wide labral excision (of at least 60°) down to bone; we used this approach when there was an absence of reparable tissue. Of these 14, nine were available for voluntary reexamination. The mean age at surgery was 38 ± 9 SD years and the mean followup was 4 ± 1 SD years. All patients consented to a physical examination and an MRI arthrogram, which was evaluated for evidence of new tissue formation by four observers. A modified Harris hip score and the UCLA were recorded.

RESULTS

Regrowth of a structure equivalent to normal labrum was not observed on the MRI arthrograms. Six of nine hips had segmental defects, bone formation was found in five, and the capsule was confluent with the new tissue in six. The mean Harris hip score at latest followup was 83 ± 14, and the mean UCLA score was 6 ± 2.

CONCLUSIONS

Resection of a nonreparable acetabular labrum down to a bleeding bony surface does not stimulate regrowth of tissue that appears to be capable of normal function by MR arthrography, and patients who underwent this procedure had lower hip scores at midterm than previously reported from the same institution for patients undergoing labral repair or sparse débridement. Based on these results, we believe that future studies should evaluate alternatives to reconstructing the labrum, perhaps using ligamentum teres, because resection seems neither to result in regrowth nor the restoration of consistently high hip scores.

[Management of malignant bone tumors around the knee]

Primary bone tumors arise mostly around the knee. A treatment strategy issued from a multidisciplinary team is the key factor for an optimal management of such patients. Many durable options for reconstructing a functional limb are available, as an alternative to amputation, without lowering patients' survival. Nevertheless complications are frequent and any decision for one technique or the other should be made with the patient, appreciating the specificity of each single case. We discuss here the different techniques with their advantages and drawbacks, including long term results.

Sports and Activity Levels After Open Surgical Treatment of Femoroacetabular Impingement

BACKGROUND

Several studies indicate that professional athletes can successfully return to competition after surgical treatment of femoroacetabular impingement (FAI). However, little is known about sports and activity levels after FAI surgery in the general patient population.

HYPOTHESIS/PURPOSE

The purpose was to determine the sports behavior, satisfaction with sports ability, and activity levels in a consecutive cohort of patients with FAI who were treated by surgical hip dislocation. The hypothesis was that the majority of patients (>75%) would be active in sports at follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This retrospective study included 153 patients (mean age, 30.0 years; 40.5% female) with 192 hips treated. Sports behavior and satisfaction were determined at a mean follow-up of 59.4 months with the use of a questionnaire. Activity levels at follow-up were assessed by the Hip Sports Activity Scale (HSAS) and the University of California, Los Angeles (UCLA) activity scale.

RESULTS

Of 126 patients who were regularly active in sports before surgery, 107 (85%) were so at follow-up. Nineteen patients (12.4%) stopped participating in regular sports, and 8 (5.2%) commenced with sports after the operation. The most popular activities before surgery were skiing (22%), cycling (22%), jogging (20%), and soccer (13%). At follow-up, most patients were engaged in cycling (23%), fitness/weight training (20%), skiing (18%), and jogging (11%). Of all patients, 75% were satisfied with their sports ability, and 25% were not. Moreover, 60.3% stated that their sports ability had improved after surgery, 20.5% declared no change, and 19.2% were subjectively deteriorated. The mean pain level during sports was rated to be 2.1 according to the visual analog scale. The mean HSAS score was 3.5 (range, 0-8), and the mean UCLA score was 7.7 (range, 3-10); male patients reported significantly higher scores than did female patients on the HSAS (4.1 vs 2.7, respectively) and UCLA scale (8.2 vs 7.0, respectively).

CONCLUSION

The vast majority of patients with FAI who are treated by surgical hip dislocation return to sports activities, and most patients are satisfied with their sports ability at midterm follow-up. Activity levels are significantly higher in male patients, but this does not yield higher satisfaction rates.

Midterm results of surgical hip dislocation for the treatment of femoroacetabular impingement

BACKGROUND

Surgical treatment of femoroacetabular impingement (FAI) includes both open and arthroscopic procedures. Encouraging results have been reported for the majority of patients after surgical hip dislocation; however, most of these reports were short term and included only small cohorts.

PURPOSE

To determine the results of surgical hip dislocation in a large cohort of FAI patients at a midterm follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective study including 185 consecutive patients (mean age, 30 years; 40% female) with 233 hips treated was conducted. We determined clinical outcomes in terms of range of motion and analyzed radiographs for several criteria including the alpha angle preoperatively and at 1 year postoperatively. At latest follow-up, on average 61 months postoperatively, patient satisfaction, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Hip Outcome Score, SF-12, and University of California, Los Angeles (UCLA) activity scale scores were determined. All revisions and conversions to total hip arthroplasty (THA) were recorded.

RESULTS

Both hip flexion and internal rotation improved from preoperatively to postoperatively. Alpha angles decreased from 65.1° ± 14.2° to 42.4° ± 4.9°. At 5 years, 82% of the patients were satisfied or very satisfied with the results of surgery, and 81% would undergo the same surgery again. There were 83% who rated their overall hip function as normal or nearly normal. Mean scores for the WOMAC pain, stiffness, and function subscales were 10.3 ± 15.8, 15.9 ± 17.4, and 9.6 ± 13.0 points; for Hip Outcome Score activities of daily living and sport subscales were 89.0 ± 13.1 and 75.6 ± 23.0 points; and for the SF-12 Physical Component Scale and Mental Component Scale were 47.4 ± 6.3 and 52.3 ± 7.4 points, respectively. The mean UCLA activity level was 7.7 ± 1.9. Conversion to THA was performed in 7 hips (3%). Seven hips (3%) underwent other major revisions, and 11 (4.7%) underwent minor revisions. Female patients had a significantly increased risk for conversion to THA (odds ratio, 13.3; 95% confidence interval [CI], 1.3-92.6) and major revision (odds ratio, 19.2; 95% CI, 2.4-152.9). The mean body mass index was significantly lower in those patients who underwent conversion to THA. The need for microfracture because of residual full-thickness cartilage defects after rim trimming was a significant (P = .04) predictor of subjective dissatisfaction.

CONCLUSION

This study demonstrates that surgical hip dislocation is a successful procedure for the treatment of FAI. A majority of patients were satisfied with the results of surgery at a midterm follow-up. Older and slim female patients were at an increased risk for a less successful outcome in terms of conversion to THA and revision surgery.

Surgical hip dislocation for the treatment of femoroacetabular impingement in high-level athletes

BACKGROUND

Midterm outcome studies show that symptomatic femoroacetabular impingement (FAI) can be successfully treated by addressing the underlying pathomorphology with open or arthroscopic surgery. Although athletes may be vulnerable to hip injury from impingement, limited information is available regarding the results of open surgery in this group.

HYPOTHESIS

High-level athletes with FAI can resume their sports after surgical hip dislocation and continue professional careers for a significant period.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-two professional male athletes (19.7 ± 2.2 years) were evaluated by postal survey at a mean of 45.1 months (range, 12 to 79) after treatment by surgical hip dislocation (30 hips, cam- or mixed-type FAI; mean α angle, 69.3°; 14 ice hockey players). Evaluation included types and level of sports, subjective ratings, and CLINICAL OUTCOMES: Hip Outcome Score, SF-12, UCLA (University of California, Los Angeles) activity scale, Hip Sports Activity Scale, visual analog scale for pain. The primary outcome variable was return to professional sports; the clinical result was the secondary outcome variable.

RESULTS

At follow-up, 21 of 22 patients (96%) were still competing professionally: 19 at their previous level and 2 in minor leagues. Eighteen (82%) were satisfied with their hip surgery and 19 (86%) with their sports ability. Mean activity levels were 9.8 per the UCLA scale and 7.6 per the Hip Sports Activity Scale. Mean scores of the Hip Outcome Score-Activities of Daily Living and Sport subscales were 94.5 and 89.1. Mean scores of the SF-12 physical and mental component summaries were 51.1 and 54.3. Pain levels during sports were 1.8 per the visual analog scale.

CONCLUSION

Surgical hip dislocation for the treatment of FAI allows athletes to resume sports and continue professional careers at the same level for several years. Clinical outcomes in terms of subjective ratings and scores were favorable.

The German Hip Outcome Score: validation in patients undergoing surgical treatment for femoroacetabular impingement

PURPOSE

To cross-culturally adapt and validate the Hip Outcome Score (HOS) for use in German-speaking patients undergoing surgical treatment for femoroacetabular impingement.

METHODS

After cross-cultural adaptation (German-language version of the HOS [HOS-D]), the following metric properties of the questionnaire were assessed in 85 consecutive patients (mean age, 33.4 years; 36 women) undergoing hip arthroscopy or surgical hip dislocation: feasibility, reliability, internal consistency, and construct validity (correlation with Western Ontario and McMaster Universities Arthritis Index, Oxford Hip Score, Short Form 12, and University of California, Los Angeles activity scale). We calculated floor and ceiling effects taking the minimal detectable change into account.

RESULTS

The activities of daily living subscale of the HOS-D could be scored in all cases and the sport subscale in all but one. The HOS-D scores were highly reproducible with intraclass correlation coefficients of 0.94 for the activities of daily living subscale and 0.89 for the sport subscale. Internal consistency was confirmed by Cronbach α values >0.90 for both subscales. Correlation coefficients with the other measures ranged from -0.08 (Mental Component Scale of Short Form 12) to -0.90 (Western Ontario and McMaster Universities Arthritis Index function subscale).

CONCLUSIONS

The HOS-D is a reliable and valid self-assessment tool for patients undergoing surgical femoroacetabular impingement treatment. By use of the HOS, comparisons between studies and treatment regimens involving either German- or English-speaking patients are now possible.

LEVEL OF EVIDENCE

Level I, testing of previously developed diagnostic criteria in a series of consecutive patients with universally applied gold standard.

Late repair of abductor avulsion after the transgluteal approach for hip arthroplasty

The abductor release sometimes does not heal after a transgluteal approach for hip arthroplasty. Factors influencing the success of subsequent repair are unclear. We used magnetic resonance imaging (MRI) to compare the condition of the gluteus medius with clinical outcome after late repair of abductor dehiscence in 12 total hip patients. Evaluation included a pain rating, gait evaluation, Trendelenburg test, strength grading, and Harris Hip Score. Most had both prerepair and postrepair MRI studies to assess the repair and to grade abductor muscle fatty degeneration. Two repairs without MRI were explored surgically. Although average pain, limp, and strength scores improved significantly, rerupture occurred in 4 subjects and fatty degeneration in the gluteus medius did not improve, even with intact repair. Nine patients were satisfied; 7 of these had an intact repair. Magnetic resonance imaging and operative observations suggest that chronic degeneration in the abductor mechanism is the major impediment to successful repair.

Effects of removal of the acetabular labrum in a sheep hip model

OBJECTIVE

The aim of this study was to learn whether partial resection of the acetabular labrum would lead to degenerative arthritis in an ovine model.

METHODS

A 2 cm segment of labrum was removed from one hip in 18 mature Swiss Alpine sheep and a sham procedure was performed on the opposite side. Animals were permitted ad lib activity until sacrifice at 6, 12 or 24 weeks. The hip joint was removed en bloc, and loaded with a force of one body weight, using a custom device designed to recreate a physiologic joint reaction force. While under load, the joint was plunge frozen, and then fixed by freeze substitution using aldehydes in methanol/acetone solvents. The entire joint was embedded in methacrylate and sectioned in a standardized frontal plane following the reaction force and including the femoral neck and the acetabular fossa. The sections were evaluated for concentricity and evidence of arthrosis. Six hip joints of three sheep with no surgical procedure were loaded with high or low loads and served as non-surgical controls.

RESULTS

Degenerative changes were present in all surgical hips, but the changes were symmetrical and mild. In 16 of 18 hips, the labrum regenerated to the extent that dense fibrous scar extending from the surgically denuded origin filled the defect.

CONCLUSION

Resection of the labrum does not cause rapid degeneration or altered stability of the sheep hip.

Fluid resuscitation in infantile hypertrophic pyloric stenosis

The purpose of this analysis was to investigate biochemical disturbances at presentation and initial fluid resuscitation before surgery in infantile pyloric stenosis. The charts of 139 consecutive infants (113 boys and 26 girls) between 7 d and 20 wk of age with hypertrophic pyloric stenosis were reviewed. The infants were treated at the Department of Pediatric Surgery, University of Bern, Switzerland, in the period between 1987 and 1997. A trend towards hypokalaemia (13 of the 139 patients), hypochloraemia (39 patients) and especially metabolic alkalosis (98 patients) was frequently noted on admission. In 84 patients, data on fluid management and on circulating sodium, potassium, chloride and the acid-base balance immediately before surgery were also available. In these patients a significant correlation was found between the parenteral chloride dose given for fluid repair (y = 0.310 x; r = 0.54; p < 0.001) and the changes in plasma bicarbonate. The equation indicates that a chloride dose of 10 mmol/kg body weight is required to reduce plasma bicarbonate on average by 3 mmol/.

CONCLUSION

Since assessment of the fluid volume stated by physical examination and history is inaccurate in infants with vomiting, the severity of metabolic alkalosis helps to define the amount of fluid required for repair.