A numerical model to reproduce squeaking of ceramic-on-ceramic total hip arthroplasty. Influence of design and material

BACKGROUND

Modern ceramic (CoC) bearings for hip arthroplasty (THA) have been used in younger patients who expect improved survivorship. However, audible squeaking produced by the implant is an annoying complication. Previous numerical simulations were not able to accurately reproduce in vitro and in vivo observations. Therefore, we developed a finite element model to: (1) reproduce in vitro squeaking and validate the model by comparing it with in vivo recordings, (2) determine why there are differences between in vivo and in vitro squeaking frequencies, (3) identify the stem's role in this squeaking, (4) predict which designs and materials are more likely to produce squeaking.

HYPOTHESIS

A CoC THA numerical model can be developed that reproduces the squeaking frequencies observed in vivo.

MATERIAL AND METHODS

Numerical methods (finite element analysis [ANSYS]) and experimental methods (using a non-lubricated simulated hip with a cementless 32mm CoC THA) were developed to reproduce squeaking. Numerical analysis was performed to identify the frequencies that cause vibrations perceived as an acoustic emission. The finite element analysis (FEA) model was enhanced by adjusting periprosthetic bone and soft tissue elements in order to reproduce the squeaking frequencies recorded in vivo. A numerical method (complex eigenvalue analysis) was used to find the acoustic frequencies of the squeaking noise. The frequencies obtained from the model and the hip simulator were compared to those recorded in vivo.

RESULTS

The numerical results were validated by experiments with the laboratory hip simulator. The frequencies obtained (mean 2790Hz with FEA, 2755Hz with simulator, decreasing to 1759Hz when bone and soft tissue were included in the FEA) were consistent with those of squeaking hips recorded in vivo (1521Hz). The cup and ceramic insert were the source of the vibration, but had little influence on the diffusion of the noise required to make the squeaking audible to the human ear. The FEA showed that diffusion of squeaking was due to an unstable vibration of the stem during frictional contact. The FEA predicted a higher rate of squeaking (at a lower coefficient of friction) when TZMF™ alloy is used instead of Ti6Al4V and when an anatomic press-fit stem is used instead of straight self-locking designs.

DISCUSSION

The current FEA model is reliable; it can be used to assess various stem designs and alloys to predict the different rates of squeaking that certain stems will likely produce.

LEVEL OF EVIDENCE

Level IV in vitro study.

Total knee replacement following intra-articular malunion

INTRODUCTION

There is a lack of data on the management of osteoarthritis of the knee associated with intra-articular malunion. The present study sought to analyze and report results of total knee replacement (TKR) in this indication, including complications and technical specificities.

HYPOTHESIS

TKR for osteoarthritis of the knee associated with intra-articular malunion entails an elevated risk of complication, with impaired functional results.

OBJECTIVES

To test this hypothesis in a retrospective series of 74 cases of osteoarthritis of the knee associated with intra-articular malunion.

PATIENTS AND METHODS

A multicenter retrospective series collated the records of 74 patients (mean age, 63 ± 14 years) who underwent TKR for post-traumatic osteoarthritis of the knee associated with intra-articular malunion between 2000 and 2008. Mean trauma-to-TKR interval was 21.8 ± 19 years (range 1 to 56 years). Patients were assessed clinically and radiologically at last follow-up, using the Knee Society score as modified by the Western France Orthopedic Society (Société orthopédique de l'Ouest).

RESULTS

At a mean overall follow-up of 4 ± 3 years (range 1 to 9 years), mean knee score improved from 25 ± 12 to 85 ± 7 (P<0.001) and mean functional score from 52 ± 13 to 66 ± 10 (P=0.004). Mean flexion gain was 6°: mean preoperative flexion, 104° ± 28° (10° to 150°), vs. 110° ± 19° (20° to 130°) at follow-up. Nineteen patients (26%) had complications, 13 of which were severe and liable to affect the functional result: three extensor system avulsions, four infections, five cases of stiffness and one of instability.

DISCUSSION AND CONCLUSIONS

The present results highlight an elevated rate of complications, with poorer clinical results than those found with osteoarthritis of the knee secondary to constitutional deformity. The initial trauma, with associated hemarthrosis, and sometimes iterative surgery to reduce and fix the initial fracture, induce fibrosis and synovial attachments, leading to stiffness and hindering exposure. The patient should be informed, and warned that postoperative flexion amplitude may be improved but is bound to remain limited, especially in case of initial stiffness.

LEVEL OF EVIDENCE

Level IV: non-comparative retrospective study.

Total knee replacement in post-traumatic arthritic knees with limitation of flexion

The objective of this study is to investigate the results of total knee arthroplasty (TKA) in traumatic osteoarthritis cases with flexion restriction and to describe the technical details of their management. A multicentre series comprising 40 patients with limitation of flexion less than or equal to 90° was selected from 152 cases of post-traumatic knee arthritis with malunion. We hypothesized that the arthroplasty complication rate would be higher than in other etiologies of limitation of flexion and would require specific management strategies.

PATIENTS

In 23 cases, intra-articular malunion was present, in 15 cases extra-articular, and in two cases combined. The mean flexion was 72±23°, extension was 6±6°, and total range of motion (ROM) 66±23°. Eight cases of flexion restriction were severe (flexion<50°), six intermediate (flexion, 50-70°) and 26 moderate. In 14 cases, the anterior tibial tuberosity was osteotomized (43% intra-articular malunion and 6% extra-articular malunion). Five simultaneous realignment osteotomies were necessary. In severe cases of limitation of flexion, five extensive quadriceps releases were associated.

RESULTS

Four mobilizations under general anesthesia were performed. In the cases of severe limitation of flexion, we noted three avulsions of the patellar tendon, two cases of cutaneous necrosis, one of which was associated with deep infection, and another case of deep infection. In the cases of moderate limitation of flexion, we noted one case of nonunion of the tibial tuberosity and two cases were revised for loosening, one aseptic and the other septic. With a mean follow-up of 5±4 years, the mean flexion was 99.4°±23 for a gain of 26.7±20°. The final flexion and the gain in flexion were correlated with preoperative flexion (r=0.62 and r=-0.47, respectively). The final amplitude was 99±27° for a gain of 33±21°. The flexion gains were comparable for both types of malunion, whether they were intra- or extra-articular.

DISCUSSION

Arthroplasty provided a substantial gain in flexion. Osteotomy of the tibial tuberosity and the realignment osteotomies should be performed if necessary, with no risk of compromising the result. Superior gains can be sought in severe cases of limitation of flexion by releasing the extensor apparatus, in absence of cutaneous scar tissue retractions and recent infection.

LEVEL OF EVIDENCE

Level 4. Noncomparative retrospective study.

Arthrodesis after failed total ankle replacement

We present a series of 16 patients treated between 1993 and 2006 who had a failed total ankle replacement converted to an arthrodesis using bone grafting with internal fixation. We used tricortical autograft from the iliac crest to preserve the height of the ankle, the malleoli and the subtalar joint. A successful arthrodesis was achieved at a mean of three months (1.5 to 4.5) in all patients except one, with rheumatoid arthritis and severe bone loss, who developed a nonunion and required further fixation with an intramedullary nail at one year after surgery, before obtaining satisfactory fusion. The post-operative American Orthopaedic Foot and Ankle Society score improved to a mean of 70 (41 to 87) with good patient satisfaction. From this series and an extensive review of the literature we have found that rates of fusion after failed total ankle replacement in patients with degenerative arthritis are high. We recommend our method of arthrodesis in this group of patients. A higher rate of nonunion is associated with rheumatoid arthritis which should be treated differently.

[Results of reimplantation for infected total knee arthroplasty: 107 cases]

PURPOSE OF THE STUDY

The purpose of this study was to assess the results of reimplantations of total knee arthroplasties complicated by infection. Outcome was assessed in terms of eradicated infection and function.

MATERIAL AND METHODS

This retrospective multicentric study included 107 cases of infected total knee arthroplasties treated by changing the implants. Seventy-seven patients had a two-stage revision and thirty had a one-stage procedure. Patients were reviewed with a minimal 2-year and an average 52-month follow-up.

RESULTS

Revision arthroplasty (one- or two-stage) eradicated infection in two out of three patients. With a two-year follow-up, revision arthroplasty was successful in 77% of patients without any sepsis risk factor, in 65% of patients with one risk factor and in 33% of patients with at least two risk factors. After reimplantation for total knee arthroplasty infection, overall function outcome was good (KS knee score: 74.8 after two-stage revision and 75.5 after one-stage revision, NS). After two-stage procedures, the knee outcome was excellent in one-third of patients, good in another third and fair or poor in the final third. After one-stage reimplantation, 40% of the knees had an excellent outcome, 30% a good outcome and 30% a fair or poor outcome. Regarding functional outcome, overall results were fair (KS function score 62.5 for one-stage and two-stage revisions). Functional outcome was fair or poor in 42% of patients with a two-stage procedure and in 55% of patients with a one-stage revision (NS).

DISCUSSION

Our study was unable to disclose any difference between one-stage and two-stage revision for eradicating infection. Unfavorable systemic and local conditions decreased the rate of success after revision total knee arthroplasty for infection. Length of infection before reimplantation, number of surgical procedures and bacterial virulence or resistance were not, in our series, predicting factors for failure of septic revision total knee arthroplasty. No difference was found for the clinical and functional results between one-stage and two-stage procedures. Functional outcome was fair or poor for half of the patients after septic revision total knee arthroplsty. The use of an external device between the two procedures for two-stage revision significantly decreased the functional outcome compared with the use of a spacer. Articulated spacers did not offered any advantage compared with a static spacer for functional outcome.

Understanding medicinal taste and odour formation in drinking waters

The formation of bromophenols during chlorination of phenol- and bromide-containing waters can be critical for taste and odour problems in drinking waters. The work performed has confirmed that flavour threshold concentrations of some bromophenols are in the ng/L range. In addition, under typical drinking water conditions, kinetic experiments and model simulations performed have shown that (1) bromination is the predominant reaction pathway, (2) bromophenol reaction kinetics are rapid leading to taste-and-odour episodes that last for short periods of 10-20 min, (3) increasing phenol concentration and pH tends to increase taste and odour intensity, (4) increasing chlorine or bromide concentrations tends to shorten the duration of the taste-and-odour episode.

Mobile versus fixed-bearing total knee arthroplasty: mid-term comparative clinical results of 216 prostheses

Since the late 1970s, mobile-bearing total knee designs have been advocated as having theoretical advantages over fixed-bearing total knee replacements. At present there is no consensus as to whether there are any differences in clinical results between the two designs. We present the results of two consecutive cohorts each of over 100 prosthesis. The first cohort underwent a fixed-bearing prosthesis, whilst the second cohort received the mobile bearing variant of the same prosthesis. Both groups were assessed pre- and post-operatively using the American Knee Society knee and function scores as well as range of movement and the presence or absence of anterior knee pain. No difference was found statistically significant between the groups, either for the knee score (P=0.068), the function score (P=0.26), the range of movement (P=0.11) or the proportions of anterior knee pain (P=0.06). It is our opinion that mobile bearing knee prosthesis have still to prove their theoretical advantages in clinical practice.

Polymorphism of the cell wall-anchoring domain of the autolysin-adhesin AtlE and its relationship to sequence type, as revealed by multilocus sequence typing of invasive and commensal Staphylococcus epidermidis strains

We sequenced the adhesin-cell wall-anchoring domain of the atlE gene of 49 invasive and commensal Staphylococcus epidermidis strains. We identified 22 alleles, which could be separated into two main groups: group 1 (alleles 1 and 6 to 16, 32/49 strains) and group 2 (alleles 2 to 5 and 17 to 22, 17/49 strains). Allele 1 (the type strain sequence) was by far the most prevalent (21 of 49 strains). Multilocus sequence typing showed a clear relationship between the atlE allele and the sequence type (ST), with the "nosocomial" ST27 clone and closely related STs expressing group 1 alleles.

Is anyone too old for a total knee replacement?

The decision on whether to perform a total knee replacement in extremely elderly patients is controversial. To assess the influence of age as an independent factor for early postoperative morbidity and mortality, we did a case-control study comparing a group of 22 patients 85 years or older that was matched for known predictive factors of nonsurgical postoperative complications with a younger control group. Both groups received the same perioperative and postoperative management. We then compared the number of postoperative complications. Standardized mortality ratios were performed to assess the influence of knee replacement on mortality. The 11 patients (50%) in the elderly group had one or more medical complications, which was similar to those of the five patients (23%) in the control group. Mortality in the elderly group who had knee replacements was almost (1/2) that of the general population (standardized mortality ratio, 0.53). We think age should not be a limitation for total knee replacements in elderly patients, although they should be given consideration for special care while in the hospital.

LEVEL OF EVIDENCE

Therapeutic study, Level III (Case control study). See the Guidelines for Authors for a complete description of levels of evidence.

La révision exhaustive biennale des arthroplasties : mythe ou réalité ?

In this article, we propose a simple calculation to project quantitatively the number of consultations implied by a systematic follow-up protocol for arthroplasty surgery. In France, this surveillance schedule has become mandatory and will have a pertinent impact on health care expenditures. The longevity of implanted prostheses as well as patient life expectancies can be used to estimate the number of consultations necessary for a regular follow-up. For example, a surgeon who performs 200 arthroplasty procedures per year will have to see 17 patients per week 20 years later.

Spinal and pelvic parameters in Marfan’s syndrome and their relevance to surgical planning

Spinal deformities are a common feature of Marfan’s syndrome and can be a significant cause of morbidity. The morphology of the scoliosis associated with this condition was previously described by Sponseller, but no correlation with the pelvic parameters has been seen. We performed a retrospective radiological study of 58 patients with scoliosis, secondary to Marfan’s syndrome and related the findings in the thoracolumbar spine to the pelvic parameters, including pelvic version (tilt), pelvic incidence and sacral slope. Our results showed marked abnormalities in the pelvic values compared with those found in the unaffected population, with increased retroversion of the pelvis in particular. In addition we found a close correlation between the different patterns of pelvic parameters and scoliosis morphology. We found that pelvic abnormalities may partially dictate the spinal disorders seen in Marfan’s syndrome. Our results supplement the well-established Sponseller classification, as well as stressing the importance of considering the orientation of the pelvis when planning surgery.

Reprise fémorale par tige cimentée et greffe morcelée compactée: analyse de la migration fémorale

PURPOSE OF THE STUDY

If the bone loss is significant, revision total hip arthroplasty can be most difficult. We present a series of 30 patients with major loss of bone stock treated with the X-change (Exeter) technique for revision total hip arthroplasty.

MATERIAL AND METHODS

This prospective consecutive series included 30 reconstructions performed between 1996 and 2001. Compacted grafts with cryopreserved bone were used. Mean follow-up was 42 months (range 24-80). According to the SOFCOT classification, bone loss was stage II in one patient, stage III in 14 and stage IV in 15. The technique described by Gie, Linder and Ling was rigorously applied: smooth stem, no force on the Merckel, cement in the impacted allograft, filling of femoral bone defects. Reinforcement with plates, mesh, or wire was used as necessary to bridge cortical defects. The Postel-Merle-d'Aubigné (PMA) score was used to assess clinical outcome. Digital x-rays were obtained before and after surgery and at last follow-up to assess implant position (vertical migration and frontal deviation), changes in bone stock, and the Pierchon classification. Thirty patients were seen at two years follow-up. Two patients were lost to follow-up after two years. Material had to be removed in two patients because of mechanical intolerance. There was one postoperative fracture at six months. One patient died more than two years after implantation. The PMA score improved from 11 to 17 at last follow-up. Radiographic results showed mean 7.3 mm stem migration and mean 2 degrees frontal deviation which were not correlated with clinical presentation. The Pierchon classification revealed 20 situations of corticalization and eight of trabeculation. Factors affecting migration were modalities of graft preparation and time to first weight bearing. Migration was unchanged after twelve months.

DISCUSSION AND CONCLUSION

The functional and radiographic results remained satisfactory in light of the initial bone loss. Implant migration did not affect outcome. We have modified the surgical technique in line with these results, particularly concerning preparation of the impacted bone graft. This technique has the advantage of filling bone defects and avoiding therapeutic escalation.

[Outpatient parenteral antimicrobial therapy (OPAT) in bone and joint infections]

The medical treatment of many bone and joint infections (including chronic osteomyelitis, prosthetic joint infection, and septic arthritis) requires prolonged intravenous antimicrobial therapy. For some patients, this treatment could be administered outside the hospital in a program that offers outpatient parenteral antimicrobial therapy (OPAT). In France, we have no registry of patients receiving OPAT. Initiation of this program requires specific criteria based on a patient evaluation and selection, and an interdisciplinary team of professionals committed to high-quality patient care. Various vascular access devices and infusion pump therapy are used to administer OPAT. The most common parenteral agents for OPAT are beta-lactams and glycopeptids (specifically vancomycin). Antimicrobial courses are stopped prematurely in 3 to 10% of the cases because of an adverse reaction or vascular access complications. Several published studies demonstrate the effectiveness of OPAT and higher patient satisfaction than hospital care. In addition, OPAT is clearly more cost-effective than intravenous therapy provided in the hospital setting. Some diagnoses, such as cellulites, community-acquired pneumonia, and endocarditis may be managed with OPAT.

Use of genotypic identification by sodA sequencing in a prospective study to examine the distribution of coagulase-negative Staphylococcus species among strains recovered during septic orthopedic surgery and evaluate their significance

A total of 212 coagulase-negative Staphylococcus strains recovered prospectively during 119 surgeries for proven or suspected bone and joint infection (BJI) were identified by sodA sequencing. These strains were identified as 151 Staphylococcus epidermidis isolates, 15 S. warneri isolates, 14 S. capitis isolates, 9 S. hominis isolates, 6 S. lugdunensis isolates, 5 S. haemolyticus isolates, 4 S. caprae isolates, 4 S. pasteuri isolates, 3 S. simulans isolates, and 1 S. cohnii isolate. Only S. epidermidis, S. lugdunensis, S. capitis, and S. caprae were found to be infecting organisms and were involved, respectively, in 35 (81.4%), 3 (7.0%), 3 (7.0%), and 2 (4.6%) cases of BJI.

[Tibia nonunion after intramedullar nailing for fracture: decortication and osteosynthesis by medial plating]

PURPOSE OF THE STUDY

Intramedullar nailing is now widely used for fractures of the tibia. Extension of nailing indications to proximal, distal, and comminuted fractures has led to a significant rate of complications. The purpose of this study was to analyze decortication and medial plating for the treatment of tibial nonunion after intramedullary nailing.

MATERIAL AND METHODS

Eighteen cases of aseptic tibial nonunion after nailing for fracture were treated in three women and fifteen men, mean age 39 years (19-57). The initial classification was open (n = 8), segmental (n = 3), single-focus (n = 15). The fracture site was inferior (n = 6), middle (n = 7), and superior (n = 2). Primary nailing used reaming in 15 cases (83%), unreamed in 3 (17%) static in 13 and dynamic in 5. Four plaster cabts were also applied. Complications were: infection (n = 1), compartmental syndrome (n = 2), tibial nerve palsy (n = 1), dysesthesia (n = 2), and protrusion of the nail into the knee (n = 1). Dynamization was performed in 11 patients, one with additional bone graft and fibulectomy. Repeated reamed nailing was performed in one patient. Seven nonunions were atrophic and 11 were hypertrophic. There were 13 malpositionings associated with the nonunion. Treatment of the nonunion was performed 300 days on average (90-900) after nailing: cancellous bone graft was associated with decortication in four cases because of bone loss (n = 3) or atrophic nonunion (n = 1).

RESULTS

Union rate was 94%. Mean time for union was 108 days (80-180) with no significant difference (Student t-test) between atrophic (119 days) and hypertrophic (103 days) nonunion. Correction of the malposition was incomplete in seven patients, with angular malunion of less than 6 degrees in five patients and greater than 10 degrees in two. One late infection occurred and finally healed after external fixation and antibiotic therapy. No skin necrosis occurred. Five patients had pain on the hardware. Removal was performed in one time and pain resolved. Improvement of knee and ankle stiffness was achieved in all patients.

DISCUSSION

This technique has been used in our department since 1967. Different studies have found a union rate ranging from 94% to 100% with this procedure. Intramedullary nailing, sometimes associated with bone graft or decortication, is also used for tibial nonunion with a good rate of union. The main problem of intramedulary nailing for nonunion, as for fracture, is the difficulty in avoiding malunion. Plating a nonunion, as a fracture, enables better reduction. Skin problems can occur with the medial plate if the soft tissues are damaged. This situation is very uncommon in secondary surgery.

CONCLUSION

Decortication and medial plating was a safe and efficient treatment for tibia nonunion after failure of intramedullary nailing and allows better reduction and repeated nailing.

Replacement arthroplasty in the weight-bearing shoulder of paraplegic patients

We review the early results of shoulder arthroplasty in the weight-bearing shoulder of long-term paraplegic patients. We have been unable to find previously published results of this subgroup of shoulder arthroplasty patients in the literature. Five paraplegic, female patients who had undergone shoulder arthroplasty were analyzed. All patients had been prospectively assessed with the American Shoulder and Elbow Surgeons (ASES) function score and the Constant score. The mean age at the time of surgery was 70 years. Three shoulders had full-thickness rotator cuff tears, and two were repaired at the time of shoulder arthroplasty. The mean preoperative Constant score was 30 out of 100, improving to 52 out of 100 at a mean follow-up of 30 months (range, 24-36 months). The mean preoperative ASES function score was 28 out of 55, improving to 37 out of 55. One patient was pain-free after surgery, and the mean postoperative pain score was 10 out of 15. There were no features of progressive radiolucency around the glenoid or the humeral components at last review apart from one case in which glenoid implant migration occurred. In view of the satisfactory improvement in terms of pain, mobility, and independence, we believe that it is reasonable to continue to offer this procedure to this subgroup of patients. We will, however, remain vigilant with regard to any further complications arising in these prostheses in the medium to long term as a result of increased loading.

Midterm results of the Salto Total Ankle Prosthesis

The Salto Total Ankle Prosthesis is noncemented with mobile bearings and is characterized by an anatomic design and a dual Ti-HA coating. Between 1997 and 2000, 98 consecutive Salto prostheses were implanted. At last followup, two patients were deceased, one patient was lost to followup, and two prostheses were removed in two patients. Ninety-three implants in 91 patients were available with a mean followup of 35 months (range, 24-68 months). Survivorship at 68 months, with the end point implant removal, then was 98% (favorable scenario) to 94.9% (unfavorable scenario). The American Orthopaedic Foot and Ankle Society score was 32.3 points preoperatively and 83.1 points at followup. Seventy-two patients are pain-free, 54 patients walk unlimited distances, and 25 patients have limitation but walk more than 1 km. Sixty-seven patients have no limp but seven need walking aids. Fifty-eight patients can walk on tiptoes, 49 patients can walk on uneven ground, 14 patients can run, 76 patients ascend stairs normally, and 63 patients descend stairs normally. Range of motion as measured on stress radiographs improved from 15.2 degrees preoperatively to 28.3 degrees at followup. Preliminary results of the Salto prosthesis are encouraging and validate the concept of anatomic replacement.

Public thresholds for chlorinous flavors in U.S. tap water

Considering this rapid growth in the purchasing of bottled water and home filtration devices, utilities are increasingly concerned about consumer dissatisfaction with tap water quality. This project aimed to characterize public perceptions of chlorinous flavors in drinking water, and how these impact customers' choices with respect to consumption of tap water alternatives. On-site taste tests at seven water utilities with 30 to 40 panelists at each site, were conducted using a forced-choice triangle test method (ASTM method E679-91) to measure public sensitivity to chlorine and chloramine in drinking water. The chlor(am)ine concentration increased from set to set. The best-estimate sensitivity limit for each panelist was the geometric mean of that concentration at which the last miss occurred and the next (adjacent) higher concentration. The measured sensitivity limit of average American populations to free chlorine (159 persons tested) and chloramine (93 persons tested) in tap water were 0.8 and 3.7 mg/L Cl2, respectively. These thresholds are much higher than those previously reported in the literature using trained FPA panels. No significant differences were observed between tap water users and users of tap water alternatives or between the various markets tested with respect to average sensitivity, though individual sensitivity varied widely.

Chlorinous flavor perception in drinking water

Chlorinous flavors at the tap are the leading cause of customers' complaints and dissatisfaction with drinking water. To characterize consumer perception and acceptance to chlorinous tastes, extensive taste testing was performed with both trained panelists and average consumers. Taste testing with trained panelists showed that chlorine perception is underestimated by disinfectant flavor thresholds reported in the literature. However, trained panelists significantly overestimate the average consumer's ability to perceive chlorine. In addition, consumer perception seems to be influenced by the chlorination practices of the country they live in. Among water quality characteristics that may influence chlorine perception, temperature was not found to induce any significant change. The influence of total dissolved solids (TDS) on chlorine perception remains unclear and, as reported elsewhere, background tastes such as musty, may significantly impact chlorine threshold.

[Use of combined gallium-technetium scintigraphy to determine the interval before second-stage prosthetic reimplantation in hip arthroplasty infection: a consecutive series of 30 cases]

PURPOSE OF THE STUDY

We report a series of 30 consecutive patients with chronically infected total hip replacement in a prospective treatment protocol that included two-stage revision surgery and scintigraphic monitoring. The serial bone scans were used to evaluate the course of infection, but not for diagnosis. Negative scintigraphic results were required before the second-stage prosthesis reinsertion after laboratory, clinical, and radiographic normalization were achieved.

MATERIAL AND METHODS

Between 1987 and 1997, we prospectively followed thirty patients, who had a chronically infected hip arthroplasty treated by the conventional two-stage revision procedure using scintigraphic verification. For the present series, negative bone scan results were achieved in the resected hip before reinsertion of the prosthesis in all patients except one. The labels used were in every case gallium-67 and technetium-99m MDP with early and late (after 30 hours) scans. A scintigraphic result was considered positive if more gallium than technetium was fixed at a site. Our conventional medical and surgical protocol consisted of an initial complete excision of all foreign bodies with systematic parenteral administration of two antibiotics after having searched for the causative organism. A spacer was never used. Tibial pin traction was always applied during the duration of drainage of the wound. The antimicrobial regimen was administered to all of these patients for 3 months. The prosthesis was reinserted when C-reactive protein (CRP) levels returned to normal and negative scintigraphic results were obtained after a period with no antibiotic therapy. Reimplantation of the prosthesis was always performed with preventive antibiotic therapy selected according to the susceptibility of the initial organisms and begun after collecting new intraoperative bacteriological culture specimens. This antibiotic therapy was pursued only for the duration of the postoperative drainage.

RESULTS

This follow-up based on combined technetium-gallium bone scans demonstrated two major advantages. First, no recurrence of infection was observed except in the single patient for whom the protocol was not observed. The second advantage was to permit nonarbitrary determination of the moment of reimplantation of the prosthesis, as there is no clear consensus regarding the interval before reinsertion in the literature. The patients underwent the second-stage of hip reconstruction after a mean interval of 9 months. The mean delay before negative scintigraphic results was 7 months.

DISCUSSION

This method, which determines the optimum delay before reimplantation reducing the risk of reinfection to a minimum, gave promising results in this prospective study of 30 patients.

[Original valgus tibial osteotomy by internal opening and without loss of bone contact. Technique and incidence of consolidation speed: a preliminary series of 33 cases]

PURPOSE OF THE STUDY

We propose an original open wedge medial osteotomy of the upper tibia. This new technique, unlike conventional open wedge osteotomies, allows a large bone contact surface without requiring graft filling.

MATERIAL AND METHOD

The new technique is based on two anterior and posterior hemi-osteotomies instead of the single osteotomy with the classical technique. The two hemi-osteotomies join laterally but start medially at very different heights on the tibia. The two hemi-osteotomies open a wedge but nevertheless lead to a very large bone contact due to the slippage in a frontal connecting frontal osteotomy. The technique uses a cutting guide to allow perfect orientation meeting the requirements of the operative plan. We studied prospectively the first 33 patients who underwent this new procedure in two centers (Jouvenet Clinic and Tenon Hospital, Paris). We report here the effect on healing time.

RESULTS

There was one failure (retarded healing and partial loss of correction) due to incomprehension of the postoperative instructions. The other 32 cases consolidated in 45 days. No graft filling was needed.

[Subcutaneous tenotomy of Achille's tendon in adults for ankle stiffness. A review of 80 cases]

PURPOSE OF THE STUDY

Lengthening of Achille's tendon is part of surgical program for ankle stiffness in equinus deformity. Usually this lengthening is done by opened surgery with all the well-knowned advantages in term of adjustment. We used a percutaneous method for Achille lengthening with a two stages tenotomy. The purpose of this study is to evaluate advantages, inconvenients and efficiency of the subcutaneous method versus the open method.

MATERIALS AND METHODS

We present a retrospective study of a 80 percutaneous lengthening of Achille's tendon in 78 patients done between August 85 and January 96. All patients who went to surgery during this period were reviewed. Mean age was 36 years old and there was 39 left sides and 41 right sides. We separated the extra-articular stiffness (48 cases) and the intra-articular stiffness (32 cases) because in extra-articular etiology the stiffness is a consequence of a primitive neuro-muscular disease as the ankle joint is healthy. 46 ankles had a past history of surgery. The kind of surgery was directely related to the etiology of the equinus. Most of the time, Achille lengthening was the last time of joint mobilisation. Only 15 times lengthening of the equinus tendon was done isolated. We looked at the early results for all patients and late results were only evaluated for the patients who had an isolated lengthening of the Achille tendon the for stastitical reasons.

RESULTS

Median follow-up is two and an half years. There was preoperatively 59 ankles equinus and correction was constantly obtained with surgery postoperative improvment was 12 degrees of dorsal ankle flexion. In sub population of isolated achillus lengthening mean gain is 17 degrees. Only one patient had a per-operative complication with an heel anesthesia. We had no late complication related to the method.

DISCUSSION

Results of this reviewal confirms efficency of the percutaneous technique in adult. Litterature is very poor concerning Achille's tendon lengthening in adult surgery. It is a very widelly spread method in children. Only few authors have published about it in adults mainly about hemiplegic patients. Our method saves tourniquet time in heavy ankle surgery. There are no painful and sticky scar. Morbidity is very low because we only had one complication related to the method. Healing up of tendon is very good, all patients being able to rase up on their toes.

CONCLUSION

A review of our cases showed us the real efficency of this technique. It's a very simple and quick method giving good results with low morbidity. For us there is no indication of open surgery for achille's tendon lengthening.

Osteoarthritis caused by Neocosmospora vasinfecta

We report the case of a patient who developed an ankle osteoarthritis due to the Ascomycete Neocosmospora vasinfecta, following accidental multiple trauma to his legs in whilst in Africa. Antifungal susceptibility testing was performed. Despite a low amphotericin B minimal inhibitory concentration, parenteral antifungal therapy failed and amputation was required to resolve the osteoarthritis. Possible reasons for the failure of this antifungal treatment are examined.

[Simple puncture versus trocar puncture biopsy for the bacterial diagnostic evaluation of osteoarticular infections. A prospective study of 54 cases]

PURPOSE OF THE STUDY

We have performed a prospective study in 54 patients with suspected osteoarticular deep infection. The purpose of the study was to compare notch needle-biopsy versus simple punction in term of bacteriological efficiency.

MATERIAL AND METHODS

Among 54 patients (32 males, 22 females), 16 cases of deep infections were proven. There was 29 hips, 17 knees, 6 ankles, 2 elbows and 1 shoulder. Each patient was investigated with simple punction and notch needle-biopsy. Diagnostic value of both methods were evaluated by comparison with results of surgical prelevement which was the gold standard for evaluating both tests. The study was made using usual diagnostic test criteria: sensitivity, specificity, positive predictive value, negative predictive value and also likelihood ratio method.

RESULTS

Sensibility for the simple punction was 31.25 per cent and sensibility for notch needle-biopsy was 69 per cent. Specificity for simple punction was 97 per cent but for notch needle-biopsy it was 100 per cent. Positive predictive value was respectively 83.33 per cent for simple punction and 100 per cent for notch needle-biopsy. Negative predictive value was 0.71 per cent for simple punction and 0.31 per cent for notch needle-biopsy. Likelihood ratios for simple punction was 11.87 and likelihood ratios for notch needle-biopsy was infinite.

DISCUSSION

Sensibility for notch needle-biopsy of 69 per cent is two time superior to sensibility of simple punction. Notch needle-biopsy had no false positive. It is a completely specific test. Methodology was valuable because all patients who had negative result of non invasive test had no preoperative antibiotherapy, and underwent surgery for bacteriological diagnostic only.

CONCLUSION

Notch needle-biopsy is always superior to simple punction. This study leads us to modify our practice. From now on we will never use again simple punction but we will only perform notch needle-biopsy which diagnostical efficiency is superior.

A floating prosthesis for radial-head fractures

We report our experience over seven years with a floating radial-head prosthesis for acute fractures of the radial head and the complications which may result from such injury. The prosthesis has an integrated articulation which allows change of position during movement of the elbow. We present the results in 12 patients with a minimum follow-up of two years. Five prostheses had been implanted shortly after injury with an average follow-up of 49 months and seven for the treatment of sequelae with an average follow-up of 43 months. All prostheses have performed well with an improved functional score (modified from Broberg and Morrey 1986). We have not experienced any of the complications previously reported with silicone radial-head replacement. Our initial results suggest that the prosthesis may be suitable for the early or delayed treatment of Mason type-III fractures and more complex injuries involving the radial head.

A FLOATING PROSTHESIS FOR RADIAL-HEAD FRACTURES

We report our experience over seven years with a floating radial-head prosthesis for acute fractures of the radial head and the complications which may result from such injury. The prosthesis has an integrated articulation which allows change of position during movement of the elbow.

We present the results in 12 patients with a minimum follow-up of two years. Five prostheses had been implanted shortly after injury with an average follow-up of 49 months and seven for the treatment of sequelae with an average follow-up of 43 months.

All prostheses have performed well with an improved functional score (modified from Broberg and Morrey 1986). We have not experienced any of the complications previously reported with silicone radial-head replacement. Our initial results suggest that the prosthesis may be suitable for the early or delayed treatment of Mason type-III fractures and more complex injuries involving the radial head.

Articulated radial head replacement and elbow release for post head-injury heterotopic ossification

This is a case report of the release of an elbow ankylosed by post-head-injury heterotopic ossification. An extensive bony resection and soft-tissue release was required. At surgery a pathological, osteoporotic fracture of the radial head was found that could not be preserved and thus was removed. In its place an articulated "floating radial head prosthesis" was used that allowed immediate rehabilitation and avoided the need for temporary joint distraction or stabilization. The initial excellent function achieved has been maintained, at a > 3-year follow-up and without the complications experienced with silicone radial head prostheses.

[Orthopaedic treatment of colles' fractures according to judet's method]

Revision of 109 Colles' fractures treated by Judet's method confirm the safety of that technic and the overall good results (73% of anatomical results). The authors show that the results are quite different in presence or in absence of metaphyseal comminution (50 to 90% of anatomical results) and when anterior cortex of the distal fragment has crossed the anterior cortex of the proximal fragment. They also emphasise the necessity of pre-operative Xrays under traction to assess that comminution, and sometimes to correct the wrong diagnosis of strictly extra-articular fractures.

[Spontaneous umbilical cord hematoma, a rare cause of acute fetal distress]

BACKGROUND

Spontaneous umbilical cord hematoma is a rare life-threatening gestational accident.

CASE REPORT

A 26 year-old primipara was examined at 38 weeks of gestation for fetal monitoring. There were a number of fetal decelerations with loss of baseline variability. Cesarean section performed for acute fetal distress resulted in a male infant with an Apgar score of 3 at 1 minute and 7 at 5 minutes and neonatal anemia (Hb: 11.6 g/l). Four umbilical cord hematomas were observed. Microscopic examination revealed a ruptured umbilical vein without other abnormality. Post natal evolution was marked by hypoxic-ischemic encephalopathy and death.

CONCLUSION

Spontaneous umbilical cord hematoma is rare (1/5,500 births) and often due to rupture of the umbilical vein. Risk factors are shortness or traction of the cord, post-maturity and infection. Umbilical cord hematomas are usually responsible for severe fetal distress or death.