Hydroxylapatite ossicular replacement prostheses: a four-year experience.

Between 1987 and 1991, I have used 215 hydroxylapatite middle ear implants, in various styles, for hearing reconstruction. The first such implants were composed entirely of hydroxylapatite. Because of intraoperative difficulties in shaping and trimming these prostheses, hybrid prostheses using Plasti-Pore were developed. For each of four implant designs (incus, incus-stapes, PORP, and TORP), the head is constructed from hydroxylapatite and the shaft from Plasti-Pore. Extrusion rate for the hybrid prostheses is low (4.3%). Hearing results from 47 patients with the hybrid hydroxylapatite prostheses, 140 patients with total hydroxylapatite prostheses, and 75 control group patients with homograft bone or Plasti-Pore prostheses were compared. A "successful" hearing result was achieved in 51.1%, 51.4%, and 60.0% of the three groups, respectively. Surgical technique for use of the new hybrid hydroxylapatite prostheses is described.     

Failures with Plasti-Pore ossicular replacement prostheses

Plasti-Pore ossicular prosthesis failures found in our series of 246 patients with regular follow-up are reported and analyzed. Extrusions as well as poor functional results (postoperative air-bone gap greater than 25 dB) of the prostheses with and without cartilage on top have been reviewed. The overall extrusion rate was 9.3%: a higher extrusion rate occurred with prostheses without cartilage (18.4%) than with cartilage (4.4%). Thirty-six patients among those with poor postoperative hearing improvement have undergone revision surgery: the main causes of failure were a short prosthesis, a fixed stapes or footplate, adhesions of the prosthesis to surrounding structures, and the displacement of the prosthesis.     

The motion of conventional and novel total ossicular replacement prostheses during changes in static pressure.

PURPOSE: To investigate the motion of prostheses used to reconstruct ears with an absent stapes arch. STUDY DESIGN: We have studied the motion of conventional total ossicular replacement prostheses (TORPs) and a novel incus-stapes replica prosthesis (ISRP), which connects the malleus head to the footplate, during changes in middle ear pressure (+400 to -400 dPa) in fresh human temporal bones using digital video clips and photographs. The pressure in the (sealed) external auditory meatus was varied using a manual tympanometer. The displacements of the prostheses in the medial to lateral plane have been measured using the dimensioning tool of Corel Draw. RESULTS: During changes in static pressure, TORPs move more in the lateral to medial plane than ISRPs. The motion of ISRPs is similar to that of the intact ossicular chain. CONCLUSION: The ISRP design is less likely to damage the cochlea during changes in static pressure than a conventional TORP, but the maximum medial displacement of the TORPs studied was less than 0.1 mm.     

Evaluation of hydroxyapatite ossicular chain prostheses.

Hydroxyapatite (HA) middle ear prostheses have gained popularity as an alternative to human autografts and homografts. This study reports on 3 HA prostheses types: total ossicular chain prostheses, used for grafting the stapes footplate to the tympanic membrane; partial ossicular chain prostheses, used for grafting the stapes superstructure to the tympanic membrane; and Kartush incus struts (Smith & Nephew Richards Inc), used for grafting the stapes superstructure to the undersurface of the malleus. This single-surgeon study of 33 consecutive cases revealed a statistically significant difference in mean postoperative air-bone gap and airbone gap closure between incus struts (14/26 dB) or partial (22/11 dB) or total (25/10 dB) ossicular chain prostheses (t test: P<0.05). Prognostic risk factors graded by the Middle Ear Risk Index indicate a tendency for worse postoperative hearing with increasing Middle Ear Risk Index. This study supports the use of HA ossicular prostheses and, in particular, the use of the malleus for ossicular chain construction.     

BMP-HA人工听骨在显微外科鼓室成形术中的应用

目的探时骨形态发牛蛋白(BMP)复合多孔羟基磷灰石(HA)人工听骨在鼓室成形术的应用效果，以寻找较理想的听骨链重建材料。方法回顾分析1999至2001年间采用BMP复合HA人工听骨行鼓室成形术63例(69耳)，其中45耳用部分听骨赝复物(PORP)，24耳用全听骨赝复物(TORP)、结果术后听力提高超过15dB HL者65耳(94．2％)，气骨导差小于20dB HL者48耳(69．6％)，听力达应用水平者55耳(79．7％)，尢排斥反应，无听骨脱出，无中耳炎复发。结论BMP／HA人工听骨生物相容好，是一种理想的中耳传音结构重建材料     

A universal ossicular replacement prosthesis: clinical trials of 152 cases

An ossicular replacement prosthesis is described that advances implant design in several respects. The head is a flattened egg shape, which eliminates pressure points against the pars tensa and provided balance on the stapes. Dense hydroxylapatite ceramic provides maximal biocompatibility. The shaft, of either Teflon or Plastipore, is easily cut to size and is replaceable to minimize wastage. Interchangeable partial or total shaft variants are provided. Trials in more than 200 patients have produced optimal results. Among 152 mature patients in 85% of the good-risk cases, the air-bone gap closed to within 20 dB and in 65% to within 10 dB; in 69% of all cases the gap closed to within 20 dB. Extrusion rates were 5% in good-risk cases and 7% overall. Long-term extrusions have not occurred. Inasmuch as cartilage interpositioning is unnecessary, the prosthesis is rapidly prepared and implanted by an easily mastered technique.     

Synthetic meniscus replacement: a review

The number of meniscus-related operations continues to rise due to the ageing and more active population. Irreparable meniscal lesions generally require (partial) meniscectomy. Although a majority of the patients benefit from pain relief and functional improvement post-meniscectomy, some remain symptomatic. As an alternative to a meniscal allograft, which is only indicated for the severely damaged meniscus, most patients can nowadays be treated by implantation of a synthetic meniscal substitute. Currently three of these implants, two partial and one total replacement, are clinically available and several others are in the stage of preclinical testing. Grossly, two types of meniscal substitutes can be distinguished: porous, resorbable implants that stimulate tissue regeneration and solid, non-resorbable implants that permanently replace the whole meniscus. Although the implantation of a porous meniscus replacement generally seems promising and improves clinical outcome measures to some degree, their superiority to partial meniscectomy still needs to be proven. The evaluation of new prostheses being developed requires a wider focus than has been adopted so far. Upon selection of the appropriate materials, preclinical evaluation of such implants should comprise a combination of (in vitro) biomechanical and (in vivo) biological tests, while up to now the focus has mainly been on biological aspects. Obviously, well-defined randomised controlled trials are necessary to support clinical performance of new implants. Since the use of a meniscus replacement requires an additional costly implant and surgery compared to meniscectomy only, the clinical outcome of new products should be proven to surpass the results of the conventional therapies available.     

Tracheal replacement: a critical review

This review discusses the need for tracheal replacement, distinct from resection with primary anastomosis, the requirements for replacement, and the many efforts over the past century to accomplish this goal experimentally and clinically. Approaches have included use of foreign materials, nonviable tissue, autogenous tissue, tissue engineering, and transplantation. Biological problems in each category are noted.     

Anterior cruciate ligament replacement: a review

The anterior cruciate ligament (ACL) is the major intra-articular mechanical element that limits motion of the tibia with respect to the femur. It is a multi-fasciculated structure composed of crimped aligned collagen fibers. The purpose of this paper is to review the literature on ACL structure and mechanical properties in an effort to stimulate the development of a new generation of more effective replacement devices. Replacement of the ACL is achieved using biologic and synthetic grafts. Biologic grafts include illiotibial band, semitendinosus and gracilis tendons, patellar tendon, and meniscus. Bone-patellar-bone complexes used to replace the ACL are revascularized and ultimately replaced by neo-ligament. Synthetic implants including the Integraft, Leads-Keio ligament, Gore-Tex? ligament and Kennedy Ligament Augmentation Device (LAD) have either not been approved or approved by the FDA for limited use as a replacement for the ACL. The Kennedy LAD has been found to increase the strength of autogenous tissue during revascularization. Based on the success of autografts and the Kennedy LAD, we conclude that the next generation of ACL replacement devices will consist of a scaffold and a biodegradable augmentation device. The scaffold will have a structure that mimics the normal ACL as well as stimulates revascularization and healing. A biodegradable augmentation device will be employed to mechanically reinforce the scaffold without stress shielding the neo-ligament. By combining the advantages of autografts and a biodegradable augmentation device, a new generation of ACL replacements will be achieved.     

Titanium fibermetal segmental replacement prostheses. A radiographic analysis and review of current status

Thirteen patients with titanium fibermetal segmental bone/joint prostheses at a minimum follow-up period of six months were reviewed. Detailed radiographic data were analyzed quantitatively in terms of stem/bone interface radiolucency and bone bridging over the segmental portion of the prosthesis at predefined zones. Although stem radiolucent lines were common in this series, only one case had clinical loosening and required reoperation. There were two cases of stem fracture; one achieved extracortical bone union without revision, and the other case required implant removal and revision. Analysis of the retrieved specimen revealed histologic evidence of bony ingrowth. The use of a long side plate for initial implant fixation might have been partially responsible for this complication because of inhibition of new bone formation over the porous-coated segment. Sequential study of radiograms at different follow-up time periods with the same zonal analysis criteria revealed that no progression of radiolucency occurred at the bone/prosthesis interface, and bone formation over the segmental portion either increased or stabilized with time. The patients' functional results and implant performance seemed to indicate that the porous-coated segmental prosthetic system was effective in bridging skeletal/joint defects. However, further improvements are needed in prosthetic design and implant quality control in order to minimize device-related complications.     

全踝关节置换假体设计的研究进展

全踝关节假体至今经历了50余年,已从第一代发展到了第三代。近年来,随着假体设计和假体材料的改进以及截骨定位导板的应用,假体稳定性更好,置入更加精确,使得全踝关节置换的适应证近年来也在逐步扩大。本文对人工全踝关节假体设计的研究进展进行了综述。     

Long-term performance of prostheses in mitral valve replacement

The long-term performance of prostheses in mitral valve replacement (MVR) is now available with representatives of current generation prostheses to 15 years. Mechanical prostheses have been implanted for 33 years and bioprostheses for 22 years. The predominant complication of mechanical prostheses is hemorrhage from anticoagulation and reoperation for late structural valve deterioration of bioprostheses. Mitral valve (MV) reconstruction, over MVR, is recommended whenever possible, especially with the advancement of atrial fibrillation ablation techniques. The current indications for MVR are those valvular lesions that are unlikely to be repaired by most surgeons or which long-term results are suboptimal with reconstruction. Reconstruction is more common for degenerative disease, replacement for rheumatic disease and variable for advanced ischemic and infective disease. The recommendations for MVR for mitral stenosis (MS) are moderate to severe MS with advanced functional status and severe pulmonary hypertension when percutaneous balloon valvotomy or mitral reconstruction is not feasible. MVR is recommended in non-ischemic severe mitral regurgitation (MR) and for non-reparable acute symptomatic MR, advanced symptomatic status, systolic dysfunction and/or ventricular dysfunction. The recommendations for MV surgery in ischemic MR are acute post-infarction MR with cardiogenic shock, unstable angina with persistent moderate-severe and severe MR and chronic, dilated ischemic cardiomyopathy with moderate-severe and severe MR.     

Our knee joint prostheses with patellar replacement

In the 13 years since the first Blauth total knee joint replacement was implanted, in August 1972, it has proved highly successful. This is borne out by the results of a prospective long-term study. Out of 488 patients who had been provided with such a prosthesis up to the beginning of 1984, 398, or 82%, were included in the study. Sixty patients had meanwhile died, and 24 could not be contacted. Six prostheses had to be removed. The follow-up quota of the surviving patients corresponded to 94%. The mean duration of observation was 40 months, with a minimum of 12 and a maximum of 144 months. Of the patients, 35% suffered from rheumatoid polyarthritis, and 61% from gonarthrosis. The mean postoperative flexion and extension values were 98-3-0 degrees. About 10% of the patients still claimed to suffer appreciable pain when starting to move and when bearing weight, as compared to approx. 95% preoperatively. Severe complications were 9 deep infections (2.3%) and 5 cases of aseptic loosenings (1.3%). There were no stress fractures or breakages of the prosthesis material in the patients follow up. A retropatellar pain syndrome was found in 8.3% of the patients, i.e., definite pain when standing up, on stairs, or when starting to move. For this reason the original design of the prosthesis was developed further and complemented, inter alia, by an artificial patella. The principal modifications are as follows: -The femoral section was given a concave shape in the sliding bearing of the kneecap and elongated proximally.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bent and broken femoral prostheses following total hip replacement: a case report.

The case of a 56-year-old man with a bent heavy, and a broken standard, Charnley femoral prosthesis, following total hip replacement, is presented. Both of these complications are uncommon, and as far as is known this is the first bent Charnley heavy prosthesis recorded. It is suggested that patients in the younger age group following total hip replacement should not expect to be able to lift excessively heavy weights, or to jump from any height.