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PubMed1997

Determination of polyethylene wear in total hip replacements with use of digital radiographs.

UNLABELLED: We describe a computer-assisted vector wear technique for the determination of polyethylene wear on digital radiographs. Twenty-five hips that had had a total hip arthroplasty were used to evaluate the repeatability and performance of three radiographic techniques to measure wear of the acetabular polyethylene liner: the manual technique with use of calipers described by Livermore et al., the same technique with use of a digitizing tablet, and our new technique of computer-assisted vector wear analysis. We found our new technique to be at least ten times more repeatable than the technique with use of either calipers or a digitizing tablet. Fourteen of the polyethylene liners were retrieved at autopsy, and the actual measurements of wear of those liners were compared with the measurements that had been obtained with the three radiographic techniques of wear analysis. Computer-assisted vector wear analysis outperformed the manual techniques of Livermore et al. When compared with the data obtained from the specimens retrieved at autopsy, the measurement of wear determined with the computer-assisted technique differed by an average of 0.08 millimeter, whereas the measurements obtained with use of calipers and use of a digitizing tablet differed by 0.26 and 0.25 millimeter, respectively. The performance of computer-assisted vector wear analysis in the clinical setting was evaluated with use of controls with known amounts of wear. These were mounted in pelvic phantoms, and radiographs were made with use of a setup that simulated the clinical setting. Analysis of nine controls with 2.0 millimeters of wear yielded an average measurement of wear (and a standard deviation) of 1.99 +/- 0.21 millimeters. CLINICAL RELEVANCE: Computer-assisted vector wear analysis demonstrated superior repeatability and accuracy compared with current techniques of manual analysis. Improved repeatability and accuracy in the determination of polyethylene wear should facilitate the investigation of factors related to the prosthesis and to the patient that affect the rates of wear.

Acetabulum↗
PubMed2000

Clinical results of modular polyethylene insert exchange with retention of total knee arthroplasty components.

BACKGROUND: Modular polyethylene inserts have enabled surgeons to perform an isolated tibial insert exchange while retaining well fixed components. The purpose of this study was to review the results of insert revision and to clarify the role of this option compared with that of revision total knee arthroplasty. METHODS: Fifty-six patients (sixty-three knees) were managed with revision of a tibial polyethylene insert and retention of well aligned and stable femoral and tibial components. The implants had been in situ for an average of fifty-nine months (range, two to 108 months) at the time of the insert exchange. The inserts that were removed at the time of exchange were evaluated with regard to wear of the articular surface according to the classification system of Hood et al. and with regard to undersurface wear according to the method described by Wasielewski et al. Forty-eight knees were followed for an average of 7.4 years (range, 3.0 to 12.2 years) after the insert exchange. Knees that did not require an additional operation were considered to have had a successful exchange. RESULTS: Seven of the forty-eight exchanges failed, at an average of fifty-four months, because of accelerated wear of the new insert. All seven knees required complete revision of all components. Of the twenty-two exchanges that were performed because of severe wear of the primary insert, six (27 percent) failed at an average of less than five years; thus, knees in which the exchange was performed because of advanced wear were more likely to fail again (p < 0.05). In addition, primary inserts that were removed from knees in which the exchange procedure subsequently failed had higher delamination scores than those that were removed from knees in which the exchange was successful (p < 0.05). Most of the primary inserts had substantial undersurface wear at the time of the exchange procedure. Metallosis (thirty knees) and osteolysis (nineteen knees) were unrelated to failure of the exchange. CONCLUSIONS: An isolated revision of the tibial polyethylene insert should not be performed when there is accelerated wear of the insert with severe delamination and grade-3 or 4 undersurface wear within ten years after the primary procedure. Because a variety of patient-related, implant-related, and technical factors influence polyethylene wear, the orthopaedist must consider multiple variables whenever contemplating a limited revision.

Arthroplasty, Replacement, Knee↗
PubMed2001

Dislodgment of polyethylene liners in first and second-generation Harris-Galante acetabular components. A report of eighteen cases.

BACKGROUND: Dislodgment of the polyethylene liner is an increasingly common complication following total hip arthroplasty. The purposes of this study are to present the results in a series of patients with this complication and to analyze the mode of failure. METHODS: Between November 1995 and January 2001, eighteen patients who had had a total hip arthroplasty presented with dislodgment of the polyethylene liner from a Harris-Galante metal acetabular shell. The medical records, radiographs, operative notes, and retrieved components were reviewed. In addition, scanning electron microscopy was used to study the fractured surfaces in a shell that had four broken tines. RESULTS: The components had been in situ for an average of seven years (range, three to eleven years). Seventeen components were second generation, and one was first generation. Symptoms developed spontaneously in sixteen patients, during sexual intercourse in one, and following a fall on the hip in one. Radiographs showed eccentric positioning of the head in all of the hips and broken tines in six. All of the shells were well fixed. Treatment consisted of revision of the shell in four patients, exchange of the liner in four, cementation of a new liner into the shell in seven, and cementation of an all-polyethylene cup in three. The liners had severe damage of the rim. Scanning-electron microscopy of the fractured surfaces of four tines revealed a fatigue pattern. CONCLUSIONS: We believe that, as the liner wears and becomes loose because of an inadequate locking mechanism, progressive micromotion occurs and the load increases on the polyethylene rim until it deforms and/or fractures. Subsequently, nothing prevents the liner from rotating out of the shell. As this mechanism of failure appears to include fatigue failure of the locking tines and wear of the liner, this complication is likely to increase as the components age in situ.

Acetabulum↗
PubMed2002

Survival and polyethylene wear of porous-coated acetabular components in patients less than fifty years old: results at nine to fourteen years.

BACKGROUND: Younger patients (those who are less than fifty years old) have been shown to have a high rate of failure of cemented acetabular components following total hip arthroplasty. In this report, we present the results associated with the use of an uncemented acetabular component in young patients who were evaluated at a minimum of nine years postoperatively. METHODS: Between December 1984 and December 1989, the senior author performed 174 primary total hip arthroplasties with use of a single design of porous-coated acetabular component. Seventy-one of these procedures were performed in fifty-six patients who were younger than fifty years old. Fifty-six of the seventy-one hips were available for radiographic and clinical analysis after a mean duration of follow-up of eleven years. All hips had been treated with a Harris-Galante-I porous-coated acetabular component that had been placed with a line-to-line fit and fixed with a mean of four screws. Clinical analysis was performed with use of the Harris hip score. Standardized anteroposterior radiographs were analyzed with regard to migration, radiolucent lines, pelvic osteolysis, and two-dimensional linear wear of the polyethylene. RESULTS: No metal shell was revised because of aseptic loosening, and no shell was loose at the time of the latest follow-up. A nonprogressive radiolucent line was seen in one zone in ten hips (18%) and in two zones in six hips (11%). No hip had a radiolucent line in all three zones. Pelvic osteolysis was noted in thirteen hips (23%); the osteolysis was observed in the ischium in eleven hips and around the screws in two. Survivorship analysis revealed that the probability of survival of the metal shell was 98% (95% confidence interval, 96.9% to 99.9%) at ten years. The mean rate of linear polyethylene wear (and standard deviation) was 0.15 +/- 0.10 mm/yr (range, 0.02 to 0.59 mm/yr). The wear rate was significantly increased in patients with an excellent Harris hip score (p = 0.004) and a younger age (less than thirty-eight years) (p = 0.026). With the numbers available, no relationship could be detected between the wear rate and the gender or weight of the patient, the polyethylene thickness, the abduction angle, or the femoral neck length. CONCLUSIONS: The fixation and survival of porous-coated acetabular metal shells in patients less than fifty years old was excellent after a mean duration of follow-up of eleven years. The high rate of linear polyethylene wear and the high prevalence of pelvic osteolysis are of serious concern in this patient population. Continued follow-up will be necessary to evaluate the influence of these findings on the longevity of the fixation of this prosthesis.

Acetabulum↗
PubMed2002

Cementation of a polyethylene liner into a metal shell. Factors related to mechanical stability.

BACKGROUND: Various clinical situations may make polyethylene liner exchange desirable in the setting of a well-fixed metal shell. Options have included a simple polyethylene liner exchange or revision of the entire acetabular shell. A recently introduced technique involves cementation of a new liner into a well-fixed metal shell. The purposes of this study were to quantify the mechanical integrity of this method of liner fixation, to evaluate the factors that may influence immediate liner fixation, and to compare this construct with a standard locking mechanism. METHODS: One modular acetabular cup design was evaluated. Variables that may contribute to the mechanical integrity of the construct were evaluated via lever-out and multiaxis dislocation testing methods. The variables included the size of the liner (undersized versus oversized), type of liner (all-polyethylene versus modular design), modification of the modular liner (unmodified versus grooved), and groove configuration (cruciform versus circumferential). Metal shells with and without screw-holes were also tested. The modular locking mechanism was used as the control. RESULTS: None of the constructs failed at the cement-metal interface. All undersized liners required significantly higher loads to failure than either the controls (p < 0.001) or the oversized liners (p < 0.001). Oversized unmodified liners failed at significantly lower loads than the controls did (p < 0.01). The creation of circumferential grooves in the oversized liners significantly improved the strength of the constructs (p < 0.01), making them comparable with the controls. No significant differences were found among the four undersized groups (p > 0.3). The standard locking construct (control) and the oversized unmodified construct failed at a force of 2000 N in the multiaxis dislocation test. No other construct failed with use of this test mode. CONCLUSIONS: Cementation of a polyethylene liner into a metal shell can be stronger than a conventional locking mechanism if the liner is undersized. Cementation of an oversized liner into a shell should be performed with caution. The long-term durability of this fixation remains unknown.

Acetabulum↗
PubMed2002

In vivo comparison of hip separation after metal-on-metal or metal-on-polyethylene total hip arthroplasty.

BACKGROUND: Twenty subjects were analyzed in vivo with use of video fluoroscopy to determine if the femoral head separates from the acetabular component during normal gait and to determine if the amount of separation differs between metal-on-metal and metal-on-polyethylene total hip prostheses. METHODS: Ten subjects had been treated with a metal-on-metal total hip arthroplasty and ten, with a metal-on-polyethylene total hip arthroplasty. All of the prostheses were implanted by the same surgeon utilizing the same surgical technique, and all were judged to be clinically successful (a Harris hip score of >90 points). Each subject walked with a normal gait on a level treadmill while under fluoroscopic surveillance. The two-dimensional fluoroscopic videotapes were then converted into three-dimensional images with use of a computer-automated model-fitting technique. Each implant was analyzed at various flexion angles to assess the amount of femoral head sliding. RESULTS: No femoral head sliding was observed in the subjects with a metal-on-metal implant, whereas all ten subjects with a metal-on-polyethylene implant had sliding that was greater than our threshold value of 0.75 mm. The average amount of femoral head sliding in these subjects was 2.0 mm, and the sliding was observed during the swing phase of gait. The sliding was typically seen medially while the femoral head remained in contact with the acetabular component superolaterally. CONCLUSIONS: Femoral head sliding commonly occurred following traditional metal-on-polyethylene total hip arthroplasty but not after metal-on-metal arthroplasty. These kinematic data may be of value in future hip-simulation studies to better duplicate wear patterns observed in retrieval analyses, assist in the understanding of the lubrication and wear rates of metal-on-metal designs, and facilitate designing of prosthetic components that minimize wear and optimize hip kinematics.

Acetabulum↗
PubMed2005

In vivo degradation of polyethylene liners after gamma sterilization in air.

BACKGROUND: Ultra-high molecular weight polyethylene degrades during storage in air following gamma sterilization, but the extent of in vivo degradation remains unclear. The purpose of this study was to quantify the extent to which the mechanical properties and oxidation of conventional polyethylene acetabular liners treated with gamma sterilization in air change in vivo. METHODS: Fourteen modular cementless acetabular liners were revised at an average of 10.3 years (range, 5.9 to 13.5 years) after implantation. All liners, which had been machined from GUR 415 resin, had been gamma-sterilized in air; the average shelf life was 0.3 year (range, 0.0 to 0.8 year). After removal, the components were expeditiously frozen to minimize ex vivo changes to the polyethylene prior to characterization. The average duration between freezing and testing was 0.6 year. Mechanical properties and oxidation were measured with use of the small-punch test and Fourier transform infrared spectroscopy, respectively, in the loaded and unloaded regions of the liners. RESULTS: There was substantial regional variation in the mechanical properties and oxidation of the retrieved liners. The ultimate load was observed to vary by >90% near the surface. On the average, the rim and the unloaded bearing showed evidence of severe oxidation near the surface after long-term in vivo aging, but these trends were not typically observed on the loaded bearing surface or near the backside of the liners. CONCLUSIONS: The mechanical properties of polyethylene that has been gamma-sterilized in air may decrease substantially in vivo, depending on the location in the liner. The most severe oxidation was observed at the rim, suggesting that the femoral head inhibits access of oxygen-containing body fluids to the bearing surface. This is perhaps why in vivo oxidation has not been associated with clinical performance to date.

Acetabulum↗
PubMed1993

Smoking and intestinal absorption of oral polyethylene glycols in Crohn's disease.

Intestinal absorption of orally administered polyethylene glycols with molecular weights of 634-1250 was investigated in 55 patients with Crohn's disease and in 20 healthy controls and was related to smoking habits at the time of testing. In the Crohn patients the polyethylene glycol absorption was also related to smoking habits at the time of diagnosis. Absorption of polyethylene glycols was impaired in Crohn patients compared with controls, but within both groups no difference was found among smokers, ex-smokers, and never-smokers (p > 0.05). Among the Crohn patients, those who smoked at the time of diagnosis had less impaired absorption (p < 0.02) of the smaller polyethylene glycols (634-942 Da) than those who did not. These data do not support the concept of altered intestinal permeability as the mechanism by which smoking influences Crohn's disease.

Administration, Oral↗
PubMed1986

Wear of the acetabular socket. Comparison of polyacetal and polyethylene.

Frictional characteristics of polyacetal (Delrin) sockets and of ultra-high molecular weight polyethylene sockets retrieved in revision after aseptic loosening were compared with measurements of friction in new sockets. Friction in retrieved polyacetal sockets was twice as great as in retrieved polyethylene sockets. We also found that frictional characteristics of polyacetal changed as the material aged in vivo. In contrast, friction in polyethylene sockets remained fairly constant, even though most of them contained bone-cement particles. Friction in polyacetal sockets may be important for the relatively high incidence of socket loosening of the Christiansen prosthesis. Measurements of wear of the polyacetal sockets showed a mean annual dimensional change of 240 mm3, four times greater than that reported for the Charnley polyethylene acetabular prosthesis.

Acetabulum↗
PubMed1992

Polyethylene wear of the PCA unicompartmental knee. Prospective 5 (4-8) year study of 120 arthrosis knees.

In Lund, 120 arthrosis knees had the PCA unicompartmental endoprosthesis during 1983-1987 and were followed prospectively for 5 (4-8) years. 17 knees were excluded from the final clinical follow-up because of the development of rheumatoid arthritis (2), severe neurologic disease (3), or death (12). Subjectively, 68 knees were much improved, 26 improved and 9 had failed. First-steps problems were only present in the uncemented group of 49 knees. Of the 9 failures (7 cemented and 2 uncemented) 6 were revised. The main reason for revision was loosening of the femoral component (2), tibial component (2), or both components (1), and polyethylene wear (1). However, all revised tibial components showed polyethylene wear, in 4 quite pronounced. Weight-bearing radiographs (61 knees) revealed major polyethylene wear in an additional 14 knees; not only in thin tibial components. There may be an increasing clinical problem due to polyethylene wear. With the presented findings the PCA unicompartmental knee endoprosthesis cannot be recommended.

Aged↗
PubMed1996

Polyethylene and titanium alloy particles reduce bone formation. Dose-dependence in bone harvest chamber experiments in rabbits.

Particles similar to those generated from joint replacements affect net bone formation within the Bone Harvest Chamber in rabbits. Whether these effects depend on the concentration of particulate materials is unknown. In this study, we performed a histomorphologic and morphometric analysis of net bone formation in the Bone Harvest Chamber in the presence of different concentrations of phagocytosable particles of high density polyethylene and titanium 6-aluminum 4-vanadium alloy. Chambers were implanted in 9 mature New Zealand white rabbits bilaterally. Concentrations of 10(6), 10(7) and 10(8) polyethylene particles/mL, and 10(8) and 10(9) particles/ mL of titanium alloy in 1% sodium hyaluronate carrier were implanted for 3-week periods in sequence in each of the chambers. 3-week control periods in which nothing was implanted in the chamber were included between the treatments. Increasing concentrations of polyethylene particles were associated with a more marked foreign body response and fibrosis. Net bone formation for the three polyethylene doses was reduced by 11%, 21% and 33% of controls, respectively. For titanium alloy, net bone formation was reduced by 8% and 56% of controls, for concentrations of 10(8) and 10(9) particles/mL, respectively. Our findings suggest possible adverse effects of wear debris on net bone formation and bony remodeling in the prosthetic bed, when concentrations of specific particles reach critical local levels.

Alloys↗
PubMed1983

Polyethylene glycol in conjunction with a second antibody for 24-hour radioimmunoassays of bovine prolactin and growth hormone.

Separate 24-h radioimmunoassays were validated for bovine prolactin and growth hormone using polyethylene glycol in conjunction with a second antibody for separating bound from free labeled hormone. Buffer, standards, sera, antisera, and radioiodinated hormone were added to assay tubes and incubated 24 h. The second antibody was added and incubated for 15 min. Then 1 ml of 6% polyethylene glycol (3% final concentration) was added, and tubes immediately were centrifuged. Polyethylene glycol effectively decreased incubation time. There was no significant difference of percent binding, percent nonspecific binding, or sensitivity of these assays as compared to assays requiring a 72-h incubation with the second antibody when polyethylene glycol was not used. Specificities of the assays were demonstrated by parallelism between varying volumes of bovine serum and standard hormones. Sensitivities of the assays were .4 and .8 ng for prolactin and growth hormone. Intra- and interassay coefficients of variations were 8 and 12% for prolactin and 5 and 18% for growth hormone. Recoveries of known amounts of added hormones were 81 and 75% for prolactin and growth hormone.

Animals↗
PubMed1998

Late dissociation of the polyethylene liner from a modular acetabular metal shell after primary total hip arthroplasty--a report of five cases.

Modular designs of hip prostheses have become popular recently. Along with complications inherent in all hip arthroplasty systems, modular systems have the additional potential for dissociation of components. Five male patients underwent total hip arthroplasties, in which all of the acetabular components were Harris-Galante II porous acetabular cups. Many years after the operation, the polyethylene liners were dissociated without any previous trauma or dislocation of the femoral heads, these dissociations and dislodgements were managed with open reduction. This complication can be predicted from clinical symptoms and signs. Roentgenograms must be taken and carefully compared to previous roentgenograms. We postulated two causes for the dissociation. First, the polyethylene liner was not fixed securely within the acetabular metal shell at the time of operation. Second, the locking mechanism of the acetabular metal shell was not strong enough to firmly hold the polyethylene liner within the acetabular metal shell. It does warrant that certain precautions must be taken when implanting modular components. The locking mechanism of the harris-Galante II porous acetabular component is mechanically weak and fails easily, therefore its design must be improved in an attempt to prevent postoperative dissociation of the polyethylene liner.

Acetabulum↗
PubMed1992

Gross polyethylene failure in total knee arthroplasty.

A total of 12 total knee replacements in nine patients with evidence of gross polyethylene failure at the time of revision surgery were identified. There were nine tibial and three patellar component failures. The average time from index to revision arthroplasty was 6 years (range: 0.75 to 9.63). A retrospective cohort group was identified based on date of operation. The average patient weight of the initial group was 89.6 kg (range: 76 to 104 kg), compared with 74.8 kg (range: 47 to 108 kg) (P = .045) in the control group. There was a male sex preponderance in the failure group (P = .045). The average height of the study group was 176 cm, compared to 161 cm for the control group (P = .003). Using the modified OASDI scale, the failure group had a higher activity level (P = .023). Pre-revision limb alignment in patients with failed TKA was statistically different from controls and served as an indication of polyethylene failure (P = .04). The selection of modular prosthetic component systems that allow for easy polyethylene revision is indicated in the high risk patient group identified. Close follow up is needed to minimize the sequela of polyethylene failure.

Aged↗
PubMed1998

[Failure of the polyethylene cups directly implanted into bone. A study of 32 Freeman cups after 9 years of followup (6-12 years)].

PURPOSE OF THE STUDY: A clinical and radiological assessment was performed on 32 Freeman polyethylene uncemented acetabular cups, at an average of 9 years follow up. This study was dedicated to analyze polyethylene bone direct fixation. MATERIAL: Between 1984 and 1988, 30 patients were operated for 32 total hip prostheses. Mean age of the population at the time of surgery was 66 years. In all cases the prosthesis was a cemented Müller femoral stem with a Freeman uncemented cup. The acetabular component was made with polyethylene with three pegs fitted with an offset hemispheric cup. METHOD: All patients were reviewed at 1, 3, 5 years and maximal follow-up. Their functional evaluation was performed using Merle d'Aubigné's hip rating scale: pain score, motion score and walking score. Radiological assessment was performed to identify acetabular cup migration, bone lysis, and radio lucency. Revision for acetabular cup loosening was compiled. RESULTS: Five patients died, 27 THA were evaluated at maximum follow-up. Seven revisions were performed after the fifth years. Merle d'Aubigné's score was 14 at the time of revision. X-rays evidenced more than 5 mm migration of the cup, with massive bone lysis. Merle d'Aubigné's score was 16 for the 20 remaining THA. Radiologically, 10 cups showed migration less than 3 mm, five of which with lysis. Among the 10 cups without migration, 5 showed sclerosis near the acetabulum. The study evidenced that cases of migration exceeding 5 mm induced a revision during the next 3 years. DISCUSSION: Our study confirms failure of bone polyethylene direct fixation, with 25 per cent of revision after a five years period. This seems to be the result of micro movement, wear and bone lysis. A five years follow up is not sufficient to evaluate a component, since all revisions were performed after five years. For many authors, radiological evaluation of acetabular component migration is an important criterion for uncemented prosthesis. The EBRA computerized method is an accurate method for determining early migration, and can be used for pro and retrospective studies. CONCLUSION: Our study confirms a high rate of failures of the Freeman uncemented cup at an average of nine-year period, as previously reported in literature.

Acetabulum↗
PubMed1999

[Mobility of a polyethylene tibial insert in a mobile total knee prosthesis].

PURPOSE: We have studied the mobility of a mobile tibial implant in total knee arthroplasty (TKA) by a radiographical evaluation. MATERIAL AND METHODS: We analyzed mobility of the polyethylene tibial insert of 15 "G2S" TKA implanted for one year or more. We established a dynamic radiographical evaluation. We used 3 weight-bearing radiographs: AP in extension and two lateral (one in extension and one at 90 degrees of flexion), two AP with femoral internal and external rotation, 2 strict lateral X-rays in neutral rotation in antero-posterior replacement with a 25 kilograms strength Telos, and 2 AP in varus and valgus with Telos. Wilcoxon's test and Fisher's exact test were used for statistical evaluation. RESULTS: Our study demonstrated preservation of the polyethylene mobility in tibial TKA implant in all movements: in rotation, in antero-posterior translation with Telos, and even in antero-posterior translation during physiological condition with flexion-extension weight-bearing radiographs. Statistical tests were very significant. We noticed that flexion induced anterior translation of tibial polyethylene when PCL was preserved. CONCLUSION: This study answered to our question whether mobility of TKA tibial implant persists after implantation. This mobility should reduce loosening forces to the tibia and stress in the polyethylene component. Now we have to determine the amplitude of mobility required to reach this objective.

Arthroplasty, Replacement, Knee↗
PubMed1999

Mechanism of failure in hips with an uncemented, all polyethylene socket.

The outcome of 32 patients with 33 primary total hip replacements performed using noncemented uncoated polyethylene acetabular cups (RM cup) with cemented titanium alloy monoblock stems (STH-2 stem) was reviewed. At a mean followup of 6.3 years (range, 6 months-10 years), the failure rate was 57%, more than 14 times higher than the rate typically seen with cemented polyethylene acetabular cups used with the STH stem. Failure was characterized by rapidly progressive acetabular or femoral osteolytic lesions that resulted in extensive bone loss, often in patients who had no symptoms. In addition to the debris that typically is generated by a metal on plastic bearing couple, an abundance of polyethylene particles of submicron size were produced at the cup-bone interface. Tissues retrieved from areas of osteolysis revealed the presence of intracellular submicron polyethylene particles in macrophages. It is recommended that patients with no symptoms who have RM noncemented, uncoated acetabular cups be followed up yearly and undergo early revision surgery when faced with osteolysis to prevent extensive bone loss.

Acetabulum↗
PubMed1999

Use of low dose polyethylene glycol solutions in the treatment of functional constipation.

A brief review is made of trials which used low doses of polyethylene glycol (13-30 g/day) solutions (125-500 ml/day) in the treatment of chronic functional constipation. Most of these were short-term studies, and confirmed that polyethylene glycol solution increased bowel frequency, improved defaecation and decreased stool consistency. Three studies reported that polyethylene glycol electrolyte solution accelerated transit through the large bowel. One long-term study observed remission of constipation-related symptoms in more than 70% of the polyethylene glycol electrolyte solution treated patients, and the efficacy of the treatment was maintained over a 6-month period, despite progressive reduction of daily dosage.

Cathartics↗