Cup Fixation Research Articles

Fixation method does not affect restoration of rotation center in hip replacements: A single-site retrospective study

BackgroundAseptic loosening is one of the greatest problems in hip replacement surgery. The rotation center of the hip is believed to influence the longevity of fixation. The aim of this study was to compare the influence of cemented and cementless cup fixation techniques on the position of the center of rotation because cemented cup fixation requires the removal of more bone for solid fixation than the cementless technique.MethodsWe retrospectively compared pre- and post-operative positions of the hip rotation center in 25 and 68 patients who underwent artificial hip replacements in our department in 2007 using cemented or cementless cup fixation, respectively, with digital radiographic image analysis.ResultsThe mean horizontal and vertical distances between the rotation center and the acetabular teardrop were compared in radiographic images taken pre- and post-operatively. The mean horizontal difference was −2.63 mm (range: -11.00 mm to 10.46 mm, standard deviation 4.23 mm) for patients who underwent cementless fixation, and −2.84 mm (range: -10.87 to 5.30 mm, standard deviation 4.59 mm) for patients who underwent cemented fixation. The mean vertical difference was 0.60 mm (range: -20.15 mm to 10.00 mm, standard deviation 3.93 mm) and 0.41 mm (range: -9.26 mm to 6.54 mm, standard deviation 3.58 mm) for the cementless and cemented fixation groups, respectively. The two fixation techniques had no significant difference on the position of the hip rotation center in the 93 patients in this study.ConclusionsThe hip rotation center was similarly restored using either the cemented or cementless fixation techniques in this patient cohort, indicating that the fixation technique itself does not interfere with the position of the center of rotation. To completely answer this question further studies with more patients are needed.

Fixation Failures of Dual Mobility Cups: A Mid-term Study of 2601 Hip Replacements

The use of dual-mobility cups has increased because of a low rate of dislocations combined with a 96% 15-year survival rate. However, late cup migrations have been attributed to their fixation (tripod - exact fit with two pegs and one extraacetabular screw) and the absence of porous coating. In a second-generation device, the designs were modified to achieve press-fit fixation and a layer of titanium beads was sintered on stainless steel cups. We therefore (1) determined the midterm survival of press-fit, grit-blasted, second-generation cups with or without additional screws, compared with original tripod and (2) compared survival of grit-blasted dual-mobility cups with bimetallic porous-coated cups. From a multiinstitutional trial, we reviewed 2408 patients with osteoarthritis implanted with 2601 prostheses of seven designs of a second-generation dual-mobility cup. The criteria for failure were migration, widening radiolucencies in any zone of the interface, or revision for cup loosening. The minimum followup was 5 years (mean, 7.7 years; range, 5-11 years). The 8-year survival rate of press-fit, grit-blasted cups was lower than that for press-fit, grit-blasted cups fixed with screws (91% versus 100%) and for tripod fixation (98%). The 8-year survival rate of press-fit, grit-blasted cups was less than that for press-fit, porous-coated cups made of the same alloy (91% versus 95%). The data suggested primary fixation of grit-blasted dual-mobility cups should be secured with screws. Porous coating sintered on the convex side improved midterm survivorship. No deleterious effect of metallosis resulted from sintered titanium beads on stainless steel. Long-term followup is required to confirm these findings.

Revision total hip arthroplasty using a reconstruction cage device and a cemented dual mobility cup

The main causes of total hip arthroplasty (THA) revisions are loosening and instability. Dual mobility cups were introduced to prevent instability, but their behavior during revisions with acetabular reconstruction has not been assessed. Use of a dual mobility cup cemented in a acetabular reconstruction cage device limits the risk of instability and does not hinder the acetabular fixation during THA revisions. The objective of this study was to test this hypothesis on a retrospective series of 96 revisions. At a mean follow-up of 41 months (range, 1-101 months), we analyzed a continuous series of 96 revisions using a reconstruction device (70 Kerboull™ cross-plates, six Burch-Schneider™ antiprotrusio cages, 20 custom-fit Novae ARM™ cages associated in all cases with a Novae Stick dual mobility cup cemented into the cage). Fifteen patients died at a mean follow-up of 22 months (range, 1-66 months) and four patients were lost to follow-up at a mean follow-up of 16 months (range, 9-27 months). These were acetabular revisons involving major bone loss, with 62 stage III and 26 stage IV cases on the SOFCOT classification. Eighty-seven patients (87.5%) underwent structural bone allografting. The mean Merle d'Aubigné score increased from 9.6 ± 3.06 (range, 2-16) preoperatively to 15.5 ± 2.32 (range, 7-18) at the follow-up. Ten dislocations (10.4%) occurred, five of which were delayed over three months after the index procedure (5.2%), but there were no intraprosthetic dislocations. At the follow-up, the X-rays showed eight hardware failures, including one cross-plate fracture, one hook fracture, and one flange fracture. Analysis of the radiological position of the cup showed a mean lowering of 15.6mm and a 9.4mm lateralization compared to the preoperative position. One revision for aseptic loosening and another for septic loosening were performed. Taking all-cause acetabular component exchange as a criterion, the survival rate at 8 years was 95.6% (95% CI, 93.3-97.7%) and 99.3% (95% CI, 98.9-99.6%) if the endpoint was aseptic acetabular exchange. This study confirms the advantage of dual mobility cups during acetabular reconstruction cemented in antiprotrusio cages as a way to limit, without eliminating, the risk of dislocation. Therefore cemented fixation of dual mobility cups in cages appears to be a reliable short-term option.

Effects of hydroxyapatite coating on survival of an uncemented femoral stem

Background and purpose Hydroxyapatite (HA) is widely used as a coating for uncemented total hip arthroplasty components. This has been suggested to improve implant ingrowth and long-term stability. However, the evidence behind the use of HA coating on femoral stems is ambiguous. We investigated survival of an uncemented, tapered titanium femoral stem that was available either with or without HA coating (Bi-Metric).Patients and methods The stem had been used in 4,772 total hip arthroplasties (THAs) in 4,169 patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2009. 59% of the stems investigated were coated with HA and 41% were uncoated. Kaplan-Meier survival analysis and a Cox regression model with adjustment for age, sex, primary diagnosis, and the type of cup fixation were used to calculate survival rates and adjusted risk ratios (RRs) of the risk of revision for various reasons.Results The 10-year survival rates of the HA-coated version and the uncoated version were about equal when we used revision for any reason as the endpoint: 98% (95% CI: 98–99) and 98% (CI: 97–99), respectively. A Cox regression model adjusting for the covariates mentioned above showed that the presence of HA coating did not have any influence on the risk of stem revision for any reason (RR = 1.0, 95% CI: 0.6–1.6) or due to aseptic loosening (RR = 0.5, CI: 0.2–1.5). There was no effect of HA coating on the risk of stem revision due to infection, dislocation, or fracture.Interpretation The uncemented Bi-Metric stem showed excellent 10-year survival. Our findings do not support the use of HA coating on this stem to enhance implant survival.

Primary total hip arthroplasty with dual mobility socket to prevent dislocation: a 22-year follow-up of 240 hips

The longest follow-up dual mobility series from inventor Gilles Bousquet focussing on implant survival and the incidence of dislocation. This was a retrospective study from 1985 to 1990, on 240 hips using a PF® modular femoral stem and a dual mobility Novae® tripodal socket (SERF). The 22-year follow-up global survival rate was 74%. No dislocation occurred, 41 hips were revised, including ten retentive failures (RF), 12 hips were lost to follow-up, 87 patients (99 hips) died without revision, and 90 hips were still in situ. The dual mobility socket global survival rate is comparable to similar series. The 0% dislocation rate demonstrates the success of dual mobility with regard to implant stability. The main issues were cup fixation, which might be improved by the use of macrostructures and HA coating, and osteolytic lesions, caused by polyethylene wear. Traditionally suitable for patients older than 60 years, dual mobility might be extended for use in patients over 50.

Quantitative Computed Tomography-Assisted Osteodensitometry of the Pelvis After Press-Fit Cup Fixation

As a follow-up of a previously reported three-year study, we analyzed the periprosthetic acetabular cortical and cancellous bone density changes at ten years after implantation of a press-fit cup. Prospective clinical, radiographic, and quantitative computed tomography examinations were performed within ten days and at mean periods of one, three, and ten years after total hip arthroplasty with a press-fit cup, a femoral stem with a tapered design, and alumina-alumina pairing. Periacetabular cortical and cancellous bone density (mg CaHA/mL) in the cranial, ventral, and dorsal regions about the cup were measured for twenty-four hips in vivo. All acetabular cups showed radiographic signs of stable ingrowth, and no acetabular component had to be revised. The loss of periacetabular cancellous bone density about the cup was as much as -37% cranially, -60% ventrally, and -71% dorsally; the decrease was progressive between the one-year and three-year examinations only. In contrast, cortical bone density above the dome of the acetabular cup remained constant throughout the ten-year follow-up. A moderate change in cortical bone density of -5% to -18% was seen at the level of the cup ten years postoperatively. Both periacetabular cortical and cancellous bone density changes were nonprogressive between the three-year and ten-year examinations after press-fit cup fixation.

Primary cup fixation with different designs of trapeziometacarpal total joint trapezium components: a radiostereometric analysis in a pig bone model

High loosening rates of the trapezium components of trapeziometacarpal total joint prostheses have been reported. The purpose of this study was to compare the primary press fit fixation of two different, uncemented cup designs (MOTEC and Elektra) with the primary fixation of a cemented polyethylene cup (DLC) in a pig bone model. We did a push out test to measure the maximal load strength of the implants and a low-pressure cyclic loading test combined with radiostereometric analysis to measure the micromotion of the implants. There was no significant difference in fixation strength between the two uncemented screw cup designs or between the two uncemented screw cups and the cemented polyethylene cup. However, we found that threading of the bone before insertion of the Electra screw cup weakens the primary fixation strength of the implant. The results indicate that focus should be on the insertion technique as well as on the cup design of uncemented trapezium cup implants. Further studies of trapezium implant migration in a clinical setting are needed.

Femoral and obturator nerves palsy caused by pelvic cement extrusion after hip arthroplasty.

Cement extrusion into the pelvis with subsequent palsy of the obturator and femoral nerves is a rare entity after hip replacement surgery. Cemented fixation of the acetabular cup has been considered as a safe and reliable standard procedure with very good long term results. We present a case of fifty year old female patient after hip arthroplasty procedure which suffered an obturator and femoral nerve palsy caused by extrusion of bone cement into the pelvis. Postoperative X-rays and CT-scan of the pelvis demonstrated a huge mass consisted of bone cement in close proximity of femoral and obturator nerves. The surgery charts reported shallow and weak bony substance in postero-superior aspect of the acetabulum. This weak bony acetabular substance may have caused extrusion of bone cement during press-fitting of the polyethylene cup into the acetabulum, and the following damage of the both nerves produced by polymerization of bone cement. The bone cement fragment has been surgically removed 3 weeks after arthroplasty. The female patient underwent intensive postoperative physical therapy and electro stimulation which resulted in full recovery of the patient to daily routine and almost normal electromyography results.

OS1705 人工股関節カップの表面形状による固定性評価に関する研究(OS17-2 機能材料1,OS-17 先端材料システムの力学とメゾスケールモデリング)

Artificial hip joint which has been made of fiber reinforced plastics has advantages of high degree of freedom of the design parameters. Artificial hip joint consists of three parts, Cup, Head and Stem. In the artificial hip joint, the fixation of cup and pelvis is very important. Therefore, we made cups which have protuberances on surface and evaluated the mechanical characterization for the cups. In this study, the target is an evaluation of mechanical characterization for artificial joint cup considering various surface shapes, and the torsion-compression test and numerical analysis has been carried out for the estimation of fixed torque using a cup with different density of protuberance.

Massive acetabular bone loss: Limits of trabecular metal cages

Massive acetabular bone loss (more than 50% of the acetabular area) can result in insufficient native bone for stable fixation and long-term bone ingrowth of conventional porous cups. The development of trabecular metal cages with osteoconductive properties may allow a more biological and versatile approach that will help restore bone loss, thus reducing the frequency of implant failure in the short-to-medium term. We report a case of massive bone loss affecting the dome of the acetabulum and the ilium, which was treated with a trabecular metal cage and particulate allograft. Although the trabecular metal components had no intrinsic stability, they did enhance osseointegration and incorporation of a non-impacted particulate graft, thus preventing failure of the reconstruction. The minimum 50% contact area between the native bone and the cup required for osseointegration with the use of porous cups may not hold for new trabecular metal cups, thus reducing the need for antiprotrusio cages. The osteoconductive properties of trabecular metal enhanced allograft incorportation and iliac bone rebuilding without the need to fill the defect with multiple wedges nor protect the reconstruction with an antiprotrusio cage.

Finite Element Analysis of the Contact Mechanics of Ceramic-on-Ceramic Hip Resurfacing Prostheses

Ceramics are good alternative to metal as bearing couple materials because of their better wear resistance. A Finite Element (FE) study was performed to investigate the contact mechanics and stress distribution of Ceramic-on-Ceramic (COC) hip resurfacing prostheses. It was focused in particular on a parametric study to examine the effects of radial clearance, loading, alumina coating on the implants, bone quality, and fixation of cup-bone interface. It was found that a reduction in the radial clearance had the most significant effect on the predicted contact pressure distribution among all of the parameters considered in this study. It was determined that there was a significant influence of non-metallic materials, such as the bone underneath the bearing components, on the predicted contact mechanics. Stress shielding within the bone tissue was found to be a major concern when regarding the use of ceramic as an alternative to metallic resurfacing prostheses. Therefore, using alumina implants with a metal backing was found to be the best design for ceramic resurfacing prostheses in this study. The loading, bone quality, and acetabular cup fixation conditions were found to have only minor effects on the predicted contact pressure distribution along the bearing surfaces.

Does An Enhanced Surface Finish Improve Acetabular Fixation in Revision Total Hip Arthroplasty?

High-porosity “cancellous metal” coatings have been introduced to increase the fixation and biologic incorporation of acetabular cups. The strength of initial fixation provided by a cancellous metal cups vs conventional alternatives in the deficient revision acetabulum was investigated. Cancellous, plasma-sprayed, and beaded cups (n = 9) were implanted under controlled conditions into a validated model of the revision acetabulum. The greatest differences were seen in resistance to catastrophic (spin-out) failure that, for the cancellous shell, averaged 1076 ± 265 N, which was 25% greater than the plasma-sprayed implant (859 ± 214 N, P = .04) and 218% greater than the beaded implant (338 ± 123 N, P < .01). The cancellous coating also provided greater resistance to ultimate failure. These results suggest that these new cancellous metal coatings may represent a promising alternative for fixation in revision total hip arthroplasty.

Is alumina-on-alumina ceramic bearings total hip replacement the right choice in patients younger than 50 years of age? A 7- to 15-year follow-up study

The alumina-on-alumina bearing couple in total hip replacement seems to be well adapted for young and active patients because of the absence of wear and the rarity of osteolysis. Over the long term, doubts persist as to the cementless cup fixation and on the functioning of this bearing system because of possible acoustic emissions during use. In young subjects, the ceramic-on-ceramic bearing system limits wear and osteolysis occurrences, without exposing patients to serious side effects. MATERIAL AND MEHTODS: We report the results, with between 7 and 15years of follow-up, for 32mm-diameter alumina-on-alumina implants in 76 patients younger than 50years of age (83 hips), combining cementless press-fit hemispheric cups with titanium stems, [either cemented (63 Osteal™ stems) or cementless (20 Multicône™ stems)], with particular attention paid to cup fixation and noise emissions during implant function. First-generation or Cerafit trellis™ acetabular components had a riveted titanium mesh (31 cases), whereas the most recent (Cerafit hydroxyapatite [HA]™) cups had a porous surface coated with hydroxyapatite (52 cases). Three cases of aseptic loosening of the cemented stems were observed as well as late migration of a Cerafit trellis™ cup in the 12th postoperative year. One ceramic insert broke in the eighth postoperative year. With the exception of one case, the patients, questioned retrospectively, reported no audible noise. With aseptic loosening (revised or not), the criterion for failure, the 12-year survival rate was 91±11% for the Cerafit trellis™ acetabular components and 91±16% for the cemented Osteal™ stems. The 9- and 7-year survival rates for the Cerafit HA™ cups and the Multicône™ stems, respectively, were 100%. Including all revisions for any cause, the 10-year survival rate of the entire series was 92%±11%. Despite the absence of wear and osteolysis, the long-term survival of these implants in young subjects should be improved. Although longer follow-up is necessary to formulate a definitive opinion, we tend to prefer cementless stem and cup fixation in ceramic-on-ceramic bearing systems. Level 4 retrospective study.

Pfannenwechsel bei größeren Defekten mit Antiprotrusionsringen

Replacement of a loosened acetabular cup attended by massive bone defects involving both columns. Acetabular restoration and proof fixation of a new acetabular cup to restore a pain-free joint function. Segmental acetabular bone defects involving both columns (Paprosky type 3A, 3B) with loosened acetabular cup or a Girdlestone situation. In case of pelvic discontinuity (Paprosky type 4) combination with reconstructive osteosynthesis plates (for example, Synthes company, Bochum, Germany). In cases of complete absence of the posterior and especially cranioposterior column combination with structural allograft reconstruction necessary. Relative: acetabular defects, that can be reconstructed by other, smaller implants, for example, press-fit acetabular cups. Exposure of the acetabulum by a conventional approach. Removal of the loosened acetabular cup. Cleaning of the acetabulum with a sharp spoon. Rebuilding of the hip center with a reamer. Choice of the size of the antiprotrusion ring using trial implants. Access chiseling for the inferior implant flange into the ischium. If necessary, adaptation of the superior and inferior flange alignment to the individual anatomy by bending. Filling of bone defects with allogenic bone chips. Knocking in of the inferior flange into the ischium. Simultaneous knocking in of both the ring in the acetabulum and the superior flange at the ischium. Screwing in of bolts from the interior of the ring into the iliac bone in the direction of hip forces. Additional positioning of screws due to the superior flange into the iliac bone. Cementing in of a polyethylene cup in the antiprotrusion ring. Antithrombotic prophylaxis, physical therapy, gait training under full weight bearing of the limb. 30 acetabular cup revisions with a new Burch-Schneider ring underwent prospective clinical and radiologic examination and were analyzed for an average follow-up of 20.6+/-7.8 months (3-36 months). The Harris Hip Score increased from preoperative 46.6 to postoperative 75.9 points. A loosening of the cage was not recorded.

Is the Stability of “Cancellous Metal” Shells Sufficient for Use without Screws in the Revision Acetabulum?

High porosity “cancellous” metal coatings have been introduced by several manufacturers to increase the fixation and biologic incorporation of acetabular cups. These materials have potential in expanding the indications for "mega-cups" in revision THR without the use of dome screws. This study was performed to determine the strength of initial fixation provided by a “cancellous” coated cup vs conventional alternatives in the deficient revision acetabulum.

Uncemented and cemented primary total hip arthroplasty in the Swedish Hip Arthroplasty Register

Background and purpose Since the introduction of total hip arthroplasty (THA) in Sweden, both components have most commonly been cemented. A decade ago the frequency of uncemented fixation started to increase, and this change in practice has continued. We therefore analyzed implant survival of cemented and uncemented THA, and whether the modes of failure differ between the two methods of fixation.Patients and methods All patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2007 who received either totally cemented or totally uncemented THA were identified (n = 170,413). Kaplan-Meier survival analysis with revision of any component, and for any reason, as the endpoints was performed. Cox regression models were used to calculate risk ratios (RRs) for revision for various reasons, adjusted for sex, age, and primary diagnosis.Results Revision-free 10-year survival of uncemented THA was lower than that of cemented THA (85% vs. 94%, p < 0.001). No age or diagnosis groups benefited from the use of uncemented fixation. Cox regression analysis confirmed that uncemented THA had a higher risk of revision for any reason (RR = 1.5, 95% CI: 1.4–1.6) and for aseptic loosening (RR = 1.5, CI: 1.3–1.6). Uncemented cup components had a higher risk of cup revision due to aseptic loosening (RR = 1.8, CI: 1.6–2.0), whereas uncemented stem components had a lower risk of stem revision due to aseptic loosening (RR = 0.4, CI: 0.3–0.5) when compared to cemented components. Uncemented stems were more frequently revised due to periprosthetic fracture during the first 2 postoperative years than cemented stems (RR = 8, CI: 5–14). The 5 most common uncemented cups had no increased risk of revision for any reason when compared with the 5 most commonly used cemented cups (RR = 0.9, CI: 0.6–1.1). There was no significant difference in the risk of revision due to infection between cemented and uncemented THA.Interpretation Survival of uncemented THA is inferior to that of cemented THA, and this appears to be mainly related to poorer performance of uncemented cups. Uncemented stems perform better than cemented stems; however, unrecognized intraoperative femoral fractures may be an important reason for early failure of uncemented stems. The risk of revision of the most common uncemented cup designs is similar to that of cemented cups, indicating that some of the problems with uncemented cup fixation may have been solved.

Cotyloplasty in Cementless Total Hip Arthroplasty for an Insufficient Acetabulum

BackgroundCotyloplasty is a technique that involves making a perforation of the medial wall of a shallow acetabulum and then inserting an acetabular cup with the medial aspect of its dome beyond the Kohler line. The purpose of this study was to evaluate the results of cementless total hip arthroplasty (THA) using cotyloplasty with focusing on the amount of medial cup protrusion.MethodsSixteen hips with insufficient acetabulum in sixteen patients were treated by cementless THA using cotyloplasty. The average patient age was 47 years. The diagnoses included dysplastic hip (12) and infection sequelae (4). All the patients were followed up for at least 2 years. Clinically, the Harris hip scores were assessed and radiologically, the amount of cup protrusion, the hip center movement and cup fixation were evaluated.ResultsThe average Harris hip score improved from 57 to 94 postoperatively. The average proportion of cup surface beyond the Kohler line was 44.1% and the hip centers were medialized by an average of 23 mm. Stable fixation of the acetabular cup was achieved in all the cases except one. In this one case, migration of the cup was detected 2 weeks postoperatively and a reoperation was performed.ConclusionsUsing cotyloplasty, good coverage of the acetabular cup was obtained without a block bone graft, and the hip joint centers were medialized. However, the safety margin for the amount of protrusion should be established.

Acetabular revision of total hip arthroplasty using a press-fit dual mobility cup

Dual mobility cups are especially indicated in total hip replacement revision, the risk of recurrent instability being greater than in primary surgery. In revision, however, primary cup fixation is uncertain without routine anchoring screws.

Safe Zone for Transacetabular Screw Fixation in Prosthetic Acetabular Reconstruction of High Developmental Dysplasia of the Hip

Prosthetic reconstruction of hips with Crowe type-IV developmental dysplasia (a high complete dislocation) is technically demanding. Insufficient osseous coverage and osteopenic bone stock frequently necessitate transacetabular screw fixation to augment primary stability of the metal acetabular shell. We sought to determine whether a previously reported quadrant system for screw fixation of the acetabular cup can be applied in patients with high dislocation of the hip and to define a specialized safe zone for screw fixation in these hips, if needed. Using volumetric computed tomographic data and image-processing software, we made three-dimensional reconstructions of the osseous and vascular structures in eighteen hips in twelve patients. We virtually reconstructed a cup in the true acetabulum and dynamically simulated transacetabular screw fixation. We mapped the hemispheric cup into several areas and, for each, measured the distance between the virtual screw and the external iliac (femoral) and obturator blood vessels. In the six patients with unilateral high dislocation of the hip and a relatively normal, contralateral hip, the six relatively normal hips served as controls. Reconstruction of the cup at the level of the true acetabulum shifted the center of rotation anteroinferiorly in the hips with a high, complete dislocation. Screws guided by the quadrant system frequently injured the obturator blood vessels in the hips with a high dislocation. In these patients, the safe zone shifted as a result of moving the prosthetic cup. The quadrant system, although helpful in determining screw placement in hips with a normal center of rotation, can be misleading and of less value in guiding screw insertion to augment acetabular shells for hips with a high dislocation. We believe that a safe zone specific to hips with a high dislocation should be used to guide transacetabular screw fixation.

Late Small Intestine Perforation after Cementless Total Hip Arthroplasty

We report a case of late small intestine perforation by an acetabular cup fixation screw after total hip arthroplasty (THA). A 79-year-old-woman underwent THA for hip osteoarthritis 13 years previously at another hospital. Although the acetabular cup fixation screw protruded into the pelvis, she had no symptoms. She later presented with peritonitis and was admitted to the hospital and prescribed antibiotic therapy. Computed tomography showed that the screw was adjacent to the intestine and was the likely cause of her peritonitis. After the peritonitis healed, she was referred to our hospital for surgical treatment of the screw. During laparotomy, we performed a resection of the intra-pelvic portion of the screw. The screw perforated the small intestine, so a small intestinal resection was also performed. The patient had an uneventful recovery.