Broken Stem Research Articles

What Are the MSTS Scores and Complications Associated With the Use of Three-dimensional Printed, Custom-made Prostheses in Patients Who Had Resection of Tumors of the Hand and Foot?

There are a few good options for restoring bone defects in the hand and foot. 3D-printed implants have been used in the pelvis and elsewhere, but to our knowledge, they have not been evaluated in the hand and foot. The functional outcome, complications, and longevity of 3D-printed prostheses in small bones are not well known. (1) What are the functional outcomes of patients with hand or foot tumors who were treated with tumor resection and reconstruction with a 3D-printed custom prosthesis? (2) What complications are associated with using these prostheses? (3) What is the 5-year Kaplan-Meier cumulative incidence of implant breakage and reoperation? Between January 2017 and October 2020, we treated 276 patients who had tumors of the hands or feet. Of those, we considered as potentially eligible patients who might have extensive loss in their joint that could not be fixed with a bone graft, cement, or any prostheses available on the market. Based on this, 93 patients were eligible; a further 77 were excluded because they received nonoperative treatment such as chemoradiation, resection without reconstruction, reconstruction using other materials, or ray amputation; another three were lost before the minimum study follow-up of 2 years and two had incomplete datasets, leaving 11 for analysis in this retrospective study. There were seven women and four men. The median age was 29 years (range 11 to 71 years). There were five hand tumors and six tumors of the feet. Tumor types were giant cell tumor of bone (five), chondroblastoma (two), osteosarcoma (two), neuroendocrine tumor (one), and squamous cell carcinoma (one). Margin status after resection was ≥ 1 mm. All patients were followed for a minimum of 24 months. The median follow-up time was 47 months (range 25 to 67 months). Clinical data; function according to the Musculoskeletal Tumor Society, DASH, and American Orthopedic Foot and Ankle Society scores; complications; and survivorship of implants were recorded during follow-up in the clinic, or patients with complete charts and recorded data were interviewed on the telephone by our research associates, orthopaedic oncology fellows, or the surgeons who performed the surgery. The cumulative incidence of implant breakage and reoperation was assessed using a Kaplan-Meier analysis. The median Musculoskeletal Tumor Society score was 28 of 30 (range 21 to 30). Seven of 11 patients experienced postoperative complications, primarily including hyperextension deformity and joint stiffness (three patients), joint subluxation (two), aseptic loosening (one), broken stem (one), and broken plate (one), but no infection or local recurrence occurred. Subluxations of the metacarpophalangeal and proximal interphalangeal joints in two patients' hands were caused by the design of the prosthesis without a joint or stem. These prostheses were revised to a second-generation prosthesis with joint and stem, leading to improved dexterity. The cumulative incidence of implant breakage and reoperation in the Kaplan-Meier analysis was 35% (95% CI 6% to 69%) and 29% (95% CI 3% to 66%) at 5 years, respectively. These preliminary findings suggest that 3D implants may be an option for reconstruction after resections that leave large bone and joint defects in the hand and foot. Although the functional results generally appeared to be good to excellent, complications and reoperations were frequent; thus, we believe this approach could be considered when patients have few or no alternatives other than amputation. Future studies will need to compare this approach to bone grafting or bone cementation. Level IV, therapeutic study.

Wind damage and yield recovery in rubber (Hevea brasiliensis) plantation

The recent study observed the damage type and the effect on the yield and dry rubber content (DRC) of wind damaged and one-year recovery of rubber trees. The observation covered 11 sites consisted of 8, 11, 12, and 15 years of PB 260 clone. The damage type was distinguished into curved, cracking curved, broken branch, broken stem, and uprooted. Latex samples were collected from each damage type and compared with normal trees. The observation exhibited that the broken stem and uprooted trees were found in the center of the impacted area, whereas curved and broken branch trees were located in the outer. The proportion of curved, broken branches and uprooted trees increased by plant age, while the proportion of broken stem decreased. The wind damage inflicted a significant yield loss and DRC decrease. The curved trees showed the least impact on the yield, yet it was reduced by nearly 50 %, and the DRC lower around 4.92 %. Nevertheless, when the curve was accompanied by cracking, the yield loss and the DRC decrease were more severe. The one-year recovery trees indicated that the trees did not fully recover.

Brown Spot and Stalk Rot Diseases of Maize (Zea Mays) and Susceptibility of Two Varieties to Physoderma Maydis in Far North Cameroon

Corn (Zea mays L.) is one of the most widely grown cereals in the world. However, in Cameroon, particularly in the Far North Region, yields remain low because of diseases increasing due to farming practices and climate change. This work aimed to characterize Brown Spot and Stalk Rot of corn and evaluate the susceptibility of two maize varieties to Physoderma maydis in field conditions. Two maize varieties, CMS9015, and CMS8704 were evaluated in a randomized block design. Disease symptoms were observed and described using identification keys. Microscopic characteristics of pathogens were performed using a microscope. Incidence, severity, and areas under disease curve progress (AUIPC and AUSiPC) were calculated. Brown spot occurred 3 or 4 weeks after sowing (WAS) at the growing stage in CMS8704 variety first, and stalk rot 7 WAS. Brown spot appeared in leaves and is characterized by oval yellowish spots in the leaf blade and brownish spots in the midrid. Stalk rot infects stem nodes and is characterized by brownish spots, leading to the broken stem. The incidence of brown spot increased with time and environmental conditions (rainfall). The highest incidence of Physoderma Brown Spot was recorded with CMS8704 variety 53.06 % against 51.72 % with CMS9015. Severity was respectively 54.40 % and 47.12 % with CMS8704 and CMS9015. The incidence and severity of stalk rot were almost identical in both varieties. AUIPC of PBS and PSR was higher in CMS9015 than in CMS 8704, 63 DAS. PBS and PSR infect maize production, and both varieties are susceptible to P. maydis.

Removal of an osteointegrated broken uncemented femoral stem after hip arthroplasty\u2014technical note

Broken stems are particularly challenging in revision hip arthroplasty, as no standard extraction instruments fit anymore. Well-integrated uncemented stem remnants can be particularly arduous to remove. Stem fatigue failure is not rare with modular stems. Since these are particularly useful in revision hip arthroplasty, increasing numbers of broken stems are to be expected. Usually applied techniques using cortical fenestration distally to the tip of the stem or using an extended transfemoral approach cause supplementary bone defects impairing reconstruction. We present a relatively simple and reproducible revision technique, using a limited standard approach and only regular orthopedic instruments, to extract the remnants of broken uncemented femoral stems in hip arthroplasty. This technique was applied successfully and without complications in 6 cases, permitting eventually the reimplantation of even shorter stems.

Index of Mangrove Health Around the Ex-Bauxite Mining Area, Tanjungpinang City, Riau Islands Province

There are several former bauxite mining areas on Bintan Island which until now have been left open and not managed properly. In Tanjungpinang, the location of the former bauxite mine is located around the mangrove forest ecosystem. The impact of bauxite mining that changes the structure, texture, and physical of the soil can interfere with the development of the root system and the growth of surrounding plants, including mangroves. Therefore, it is necessary to know the health condition of mangroves around the former bauxite mining area. The method used is a cluster plot by calculating the percentage of tree damage based on organ location, type, and level of damage. The results of the analysis show that the health condition of the mangrove forest in Tanjungpinang City is healthy (50,9%); slightly damaged (40,4%) and moderately damaged (8,8%). The locations of the organs that suffered the most damage were roots, lower and upper stems, and leaves. The most common type of damage found roots submerged in red mud; stems and leaves covered with dust and red sand; termite; broken stem; roots break and die; broken shoots; and the leaves change color. The greatest severity is found between 10% and 20%.

Comparison of the productivity, cost and stem breakage of two- and three-machine harvest systems clearfelling a mature Pinus radiata stand

ABSTRACT Damage to trees and logs during harvest and transport can result in major losses of wood volume and value. The study compared a harvester/forwarder (two-machine) harvest system, which typically is used in Australia, with a feller-buncher/processor/forwarder (three-machine) harvest system in terms of productivity, cost and felling stem breakage when clearfelling a 29-year-old Pinus radiata plantation in eastern Victoria, Australia. The study aimed to determine whether the three-machine harvest system reduced felling tree breakage while maintaining or improving on the productivity and delivered cost of the two-machine harvest system. The harvest systems were compared on adjacent sites (~1 ha each) using an elemental time study. Machine productivity was derived from cycle times using StanForD stem files to obtain merchantable tree volumes and forwarder load weights from the forwarder’s onboard scales. The three-machine harvest system was more productive and resulted in considerably less felling stem breakage than the two-machine harvest system (two broken stems compared with 21 broken stems). However, it was approximately 41% more expensive than the two-machine harvest system in terms of cost per m3 of logs delivered to roadside. Because chiplogs were cut from broken stem sections where possible, and it was unlikely that sawlog volume was lost through stem breakage (based on the minimum sawlog specifications and the length and large-end diameter of the broken stem sections), any financial losses resulting from the additional breakage in the two-machine harvest system were insignificant compared with the extra cost per m3 of logs delivered for the three-machine harvest system.

Kayu Limbah Penebangan Intensitas Rendah di Izin Usaha Pemanfaatan Hasil Hutan Kayu-Hutan Alam

Forest harvesting of natural-forest production in Indonesia is carried out with a high felling intensity, thus has changed the forest biomass. Several studies have shown a strong correlation between harvesting intensity and the reduction of wood volume in the forest. This condition may disrupt the stability of forest ecosystem. This study aimed to calculate and classificate logging residue of low-harvest intensity (one tree plots-1) in Indonesian Forest Concession. The study was conducted in private concessions in North Kalimantan and West Papua. Measurements were made in 30 dynamic circular sample plots with a radius of 2 times the height of the felled tree. The average size in North Kalimantan was 2.5 ha plot-1 and in West Papua was 1.5 ha plot-1. The sample plots were randomly placed in the cutting compartment. All logging residues with dbh ≥10 cm were measured after felling. The logging residue is classified into felled and unfelled trees and four types of logging residue (fallen tree, broken stem, stump, branches and twigs). The low felling intensity produced logging residue ranging from 4.98-5.55 m3 ha-1. The result indicated that logging residue came from felled trees (66%) was higher than those from unfelled trees (34%). The most common type of logging residue of felled tree was branches and twigs, broken stem and stump. The logging residue came from unfelled tree dominated by fallen tree followed by broken stem, branches, and twigs.  Keywords: felling intensity, forest conservation, natural forest, selective cutting

Contrasting patterns of natural mortality in primary Picea forests of the Carpathian Mountains

Mortality, driven by both climate and disturbance legacies, is a key process shaping forest dynamics. Understanding the mortality patterns in primary forests in the absence of severe disturbances provides information on background natural dynamics of a given forest type under ongoing climate change. This can then be compared to mortality rates in severely-disturbed stands. Using a large number of sample plots along a gradient from low to high disturbance, we examined the mortality rates and composition of mortality agents in primary mountain Norway spruce (Picea abies (L.) Karst.) forests on different spatial scales. We evaluated the mortality rates and causes of mortality in 28 stands across a large geographical gradient spanning over 1000 km. We resampled (five-year period) 371 plots (16,287 living trees) in primary Norway spruce forests along the Carpathian mountain chain. The estimated overall annual mortality rate was within the previously reported range of background (ambient) mortality, however, stand-level and plot-level mortality rates varied substantially. Over 18% of plots displayed more than 2% annual mortality and 6% of plots even exceeded 10% per year. Stands in the Western Carpathians showed the highest variability in the mortality rate, with 30% of the stands in this region showing annual mortality rates over 5%. At the plot level, mixed-severity disturbances increased variability of mortality rates within most localities. Overall mortality was evenly distributed among size classes up to 50 cm diameter at breast height (DBH). However, the distributions differ for individual mortality agents. Mortality modes were classified into six categories (broken crown, broken stem, uprooted, competition, bark beetle/fungi, climatic extremes). Bark beetle (Ips typographus L.) infestation was the most frequent mortality agent in all stands, whereas the influence of competition as a mortality agent varied substantially. Mortality from abiotically-caused physical damage was similar to that from competition, yet the distribution among modes of physical damage (uprooted, crown, or stem breakage) varied. The lack of clear evidence of mortality agents in some locations implies that many tree deaths are caused by a combination of contributing factors. The results suggest the role of bark beetle as a mortality agent does not equate to severe mortality at large scales. Prevalence of different size classes affected by individual mortality agents underline the high complexity of the mortality process in primary forests.

Long-Term Survival of the Cemented Exeter Universal Stem in Patients 50 Years and Younger: An Update on 130 Hips

BackgroundThere is variable evidence regarding survivorship beyond 20 years of total hip arthroplasties in young patients. We report the long-term results of the Exeter cemented hip system in patients ≤50 years at minimum of 20 years. MethodsClinical and radiological outcomes of 130 consecutive total hip arthroplasties in 107 patients aged 50 years or younger at primary operation were reviewed; 77% had a diagnosis other than osteoarthritis. All patients were followed at 5-year intervals, no patients were lost to follow-up, and the status of every implant is known. ResultsMean age at surgery was 41.8 (17-50) years. Mean follow-up was 22.0 (20.0-26.1) years. There were 79 hips surviving, 14 hips (11 patients) deceased, and 37 hips revised. Reasons for revision: 29 hips for aseptic cup loosening (26 stems revised using cement-in-cement, three left in-situ); three stems for femoral osteolysis, two related to acetabular polyethylene wear (14.1 and 17.0 years), one with Gaucher’s disease (21.1 years); one broken stem (12.9 years); one cup for instability (4.3 years–stem revised using cement-in-cement); and two hips with infection (8.5 and 23.8 years). There were no cases of aseptic loosening of the Exeter stem. There were no radiologically loose stems although eight patients had radiological evidence of loosening of the cemented cup. Survivorship at 22 years was 74.9% for revision for all causes and 96.3% for revision of the stem for aseptic loosening or lysis. ConclusionThe Exeter cemented stem has excellent survivorship at minimum 20 years in young patients. Acetabular component survivorship was less favorable, but the advent of highly cross-linked polyethylene may improve this in the long term.

Residual stand damage from selective logging of tropical forests: A comparative case study in central Kalimantan and West Sumatra, Indonesia

Selective logging in natural forests in Indonesia involves logging trees with a diameter at breast height (dbh) of >50 cm and leads to damage to residual stands. This research was conducted on forest concession areas in West Sumatra and Central Kalimantan to analyze residual stand damage. The type and percentage of damage were calculated at both locations by evaluating 10 plots of 1 ha at each site. All trees with a dbh of >20 cm were measured and classified before and after felling and skidding. The stand density and felling intensity were analyzed to determine the factors affecting the amount of damage. Results indicated six types of damages: broken stem, crown injury, fallen or uprooted trees, leaning, bark and stem injuries, and buttress injury. All six types of damages were found in Central Kalimantan, whereas five types of damages (except buttress injury) were found in West Sumatra. On comparing pre- and post-logging conditions, a higher percentage of damage was identified in Central Kalimantan (27.8%) than in West Sumatra (22.4%). The percentage of tree damage increased in line with the increasing felling intensity at both locations. It was concluded that a higher tree density and felling intensity resulted in a greater residual stand damage both in Central Kalimantan and West Sumatra.

A comprehensive stress indicator for evaluating plant water status in almond trees

This study evaluated a comprehensive plant water stress indicator that integrates the leaf temperature and the environmental conditions that can provide feedback on the plant response to irrigation scheduling. This quantity—Comprehensive Stress Indicator (CSI)—is based on the reformulation of the leaf energy balance equation. Specifically, CSI is the ratio of the temperature difference between a dry leaf (i.e., a leaf with a broken stem) and a live leaf (on the same tree) [i.e., Tdry-Tleaf] and the difference between the vapor pressure inside the stomatal cavity at saturation and the vapor pressure of the air at ambient temperature [i.e., es(TL)-e(TA)]. The required measurements to compute CSI include dry leaf temperature, live leaf temperature, relative humidity, and air temperature at the tree being monitored. In this study, all measurements were obtained using a sensor suite called the leaf monitor. Leaf monitors were connected to a wireless mesh network to communicate the data to a website. The leaf monitor included two thermal infrared sensors, one for the dry leaf and one for the live leaf, both of which were housed in the same unit with almost identical environmental conditions due to a diffusing hemispherical dome that enclosed these sensors. The CSI is a dynamic indicator with a value for every data sample collected. For a single indicator representing each day, the CSI was evaluated in two ways. First, the CSI was integrated with respect to time from 10 A.M. to 6 P.M. to obtain the Integrated Comprehensive Stress Indicator (ICSI). Second, the CSI was averaged from 1 P.M. to 3 P.M. to obtain the Average Comprehensive Stress Indicator (ACSI). Both ICSI and ACSI were compared to other stress indicators, including the existing Crop Water Stress Index (CWSI) and Integrated Degrees Above Non-Stressed (IDANS). Results show that ICSI and ACSI are satisfactorily correlated with midday stem water potential (SWP). The ICSI and ACSI indicators may be more convenient than other stress indicators because they require measurements only at the tree being monitored.

Fracture of the stem-neck junction in non-modular total hip arthroplasty: A case report

Fracture of non-modular femoral stem-neck junction failure after total hip arthroplasty is rare. We present a case of 52-year-old man with a fractured metal femoral stem-neck junction in a non-modular total hip replacement. The patient attended to emergency room with a fracture of the prosthetic neck of the femoral metal implant. The patient undergone a revision hip arthroplasty by splitting the femur for broken stem and implanting a new femoral stem with femoral wiring. Ceramic insert placed over the top of the acetabular ring was assembled with cement, and optimal neck length ceramic head was chosen.

A REVIEW ON PHYTOCHEMISTRY AND PHARMACOLOGICAL PROPERTIES OF MILKWEED FAMILY HERBS (ASCLEPIADACEAE)

Calotropis procera and Gymnema sylvestre are a perennial shrub and woody climber, respectively, and belonging to the family Asclepiadaceae. They are commonly known as milkweed family herbs. The Calotropis commonly have two species, i.e., C. procera and C. gigantean. All parts of plant exude white milky latex when cut. It has been widely used in traditional medicine due to its pharmacological active compounds found in all parts of plants such as bark, roots, and leaves and especially its latex which exudes from damaged or broken stem and leaves. G. sylvestre an ayurvedic herb came to be known as “destroyer of sugar” because in ancient times Ayurveda physicians observed that chewing a few leaves of G. sylvestre suppressed the taste of sugar. It also reported to possess antidiabetic, antioxidant, and immunomodulatory, antiulcer, and anticancer potential. The gymnemic acid is the main constituent which is responsible for number of pharmacological activities. The present review assembles the data on pharmacognostic and pharmacological potential of C. procera and G. sylvestre.

A simple new technique for the removal of fractured femoral stems: a case report

IntroductionThe removal of broken femoral stems has become a major issue in revision surgery, and is a technically difficult and time-consuming procedure.Case presentationWe present a case of a fracture of a cementless long femoral stem in a 65-year-old, white Caucasian man. The distal part was removed with a special longitudinal osteotomy through the anterior cortex extending distally for 10cm. It was then followed by a transversal osteotomy 2cm below the tip of the femoral stump to allow enough space for two locking pliers. Simultaneously using a lamina spreader on the distal part, the broken stem was extracted while hammering on two locking pliers.ConclusionsWe developed a simple and easy technique for the removal of a broken femoral stem that can be applied to all kinds of femoral stems and intramedullary nails regardless of their cross section. We used ordinary surgical instruments and spared the remaining bone stock.

A new strategy to remove broken femoral mega-prostheses with hollow trephine reamers

Prosthetic replacement for the reconstruction of bone tumor is the standard method in limb salvage surgery. However, the breakages of prosthesis in these patients are frequent because the patients are young and active. Removal of the broken stem remained in the bone medulla is a highly difficult technical procedure in revision surgery. This article describes a new method to remove the well-fixed broken femoral stem with a hollow trephine reamer in patients with prosthetic replacement of the distal femur for primary bone tumors.

HURRICANE OMAR WIND TOLERANT PAPAYA

During the mid and late 1990s the US Virgin Islands experienced frequent hurricanes which destroyed most of the papaya crops. From this experience, papaya breeding focused on developing short and compact lines with fruit set within 1 m of the soil. A papaya plot was established in a double-row system, 2 m between plants in a row, 1 m between rows and 3 m between sets of double rows. Papaya trees, 7 months after transplanting, latent with fruit and in the first month of harvest, were subjected to hurricane Omar force winds in October 2008. Papaya varieties over 2 m in height 'Tainung 1', 'Tainung 5', 'Known-You 1' and Kapoho had 10-20% broken stem and 70-80% were blown down. Three compact papaya lines, 1-1.5 m tall, had no broken stems and only up to 15% of the plants blown over. These results indicate that short productive trees, with a lower center of gravity, were able to tolerate hurricane force.

Technical Notes and Tips: Use of a Trephine to Extract Broken Femoral Stems

Technical Notes and Tips: Use of a Trephine to Extract Broken Femoral Stems

Gate-Valve Milling Operation Performed With Coiled Tubing

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 96685, "Pioneering ‘Gate Valve Milling’ Operation Performed With Coiled Tubing, Recovers an Important Oil Producer Offshore Brunei," by N.M. Al Araimi, SPE, Brunei Shell Petroleum; B. Gedge, SPE, and K. Burns, Weatherford; and M. Mahajan, SPE, BJ Services, prepared for the 2005 SPE Annual Technical Conference and Exhibition, Dallas, 9-12 October. Brunei Shell Petroleum offshore Well A was shut in because the 3 1/8-in. master valve on the 5,000-psi monoblock tree was stuck in the closed position because of scale. Two options were considered for recovering the well with well intervention techniques rather than a complete workover and well-kill operation. Because the nearest gate-valve milling machine was in Europe, the valve was milled by use of a coiled-tubing (CT) unit that was on the platform performing a stimulation program on adjoining wells. This operation had been performed only once before, in the North Sea. Summary During routine wellhead maintenance, the lower master gate valve on Well A was found to be stuck in the closed position, most likely because of a broken stem related to scale buildup and attempts to open the valve. A number of attempts to free the seized valve by turning the wheel handle failed. The lost production caused by this well being offline was 1,260 BOPD, with a monetary loss of U.S. $1.9 million for every 30-day period. Calcium carbonate scaling tendencies were identified as a likely cause of both the valve seizure and the progressive production decline observed since completion. A hydrochloric acid (HCl) soak treatment was performed, pumping 20 to 25 bbl acid into the wellbore. This treatment did not return the valve to operable service. The HCl soak treatment was repeated. Because the gate valve was closed, this treatment consisted of a series of 1- to 1.5-bbl acid soak pills that were pumped and left to soak on top of the closed valve. After several hours, each spent pill was displaced through the flow wing outlet. This treatment also was not successful. An alternative approach was required, and its timing was driven by a compliance need to access and test the subsurface safety valve (SSSV) that was beneath the gate valve. Milling would allow throughbore access to test the SSSV and set plugs to allow tree repair. Considerations Use of a gate-valve milling machine has proved to be successful in the past in a number of locations in the world, particularly in geothermal operations, where tree valve seizure is a common occurrence because of the often high scale production and cooling at surface, causing scale precipitation. The problem for this option was that the only unit available was in Europe. To mobilize the unit to Brunei would be expensive and time consuming, and additional equipment like blowout preventers (BOPs) also would have to be mobilized, making this a very expensive option, even if it was sound technically.

Revision Total Hip Arthroplasty with Titanium Ingrowth Prosthesis and Bone Grafting for Failed Cemented Femoral Component Loosening

Fifty-seven hips (55 patients) had revision for failed cemented femoral component loosening using titanium ingrowth femoral components and cancellous bone grafting. The patients' average age was 59 years (range, 25-86 years), and the average follow-up period was 2.8 years (range, two to six years). The preoperative hip score averaged 45.5 (range, 10.0-80.7) and the postoperative hip score averaged 82.5 (range, 43.0-100.0). Complications included dislocation (4.0%), infection (4.0%, one recurrence from a previously infected hip and one acute hematogenous infection), and a 4.0% revision rate for loose femoral component. Another patient had a revision for a loose acetabular component. All parameters of hip function (i.e., pain, limp, activities of daily living, use of support, and distance walked) improved with time. Femoral component loosening is classified into four types based on the severity of loosening and instability. In Type I there is minimal endosteal or inner cortical bone loss, i.e., loosening from the cement-metal-bone interface or a broken stem (seven hips). In Type II there is proximal canal enlargement with cortical thinning of 50% or more and sometimes a lateral wall defect with an intact circumferential wall (23 hips). In Type III there is a posteromedial wall defect involving the lesser trochanter (23 hips). In Type IV there is total proximal circumferential bone loss in varying distances below the lesser trochanter (three hips). The Harris hip scores for the four groups were 93.0, 83.0, 80.0, and 78.0, respectively.

Conventional versus resurfacing total hip arthroplasty. A long-term prospective study of concomitant bilateral implantation of prostheses.

Fifty patients requiring bilateral total hip arthroplasty underwent a concomitant conventional hip arthroplasty on one side and an articular resurfacing procedure on the other, done by the senior one of us (M. A. R.). The average age of the patients was sixty-two years (range, twenty-one to eighty-seven years), and forty-seven of them were followed with serial radiographs and clinical evaluation for one year or more. The length of follow-up was five years for thirty-four patients with both prostheses intact. The average pain score for all hips at three years postoperatively was 5.5 points. Although the majority of patients at each follow-up interval did not prefer one procedure to the other, the conventional arthroplasty was significantly superior for those who had a preference, and radiographic evaluation revealed a statistically significant increased incidence of acetabular lucency at the bone-cement interface of the resurfacing arthroplasty at one, two, three, five, and seven years postoperatively (p less than 0.002). Two of the conventional prostheses were revised during this time-period (one because of infection and one, a broken stem) whereas thirteen (26 per cent) of the resurfacing prostheses were revised (eight hips had femoral loosening, five with concomitant acetabular loosening; three had acetabular loosening; and one had a femoral neck fracture) at an average of fifty-two months postoperatively (p less than 0.001).