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Background: A phase-III trial that included fifty-three patients undergoing unilateral primary total knee arthroplasty with cement was conducted to investigate the hemostatic efficacy of fibrin sealant.Methods: Following cementing of the joint, 10 mL of fibrin sealant was sprayed onto the wound before tourniquet deflation and wound closure. No placebo was used in the control group. All patients received drains.Results: Within twelve hours after the surgery, the amount of bloody drainage was 184.5 +/- 28.9 mL (mean and standard error) in the fibrin-sealant group (information available for twenty-three patients) and 408.3 +/- 54.6 mL in the control group (information available for twenty-three patients) (p = 0.002, after adjustment for variance in the time that the drainage was measured). On the first postoperative day, the hemoglobin level had decreased by 20.1 +/- 2.1 g/L in the fibrin-sealant group (information available for twenty-two patients) and by 27.3 +/- 2.1 g/L in the control group (information available for twenty-four patients). After adjustment for baseline values, the decrease in the hemoglobin level was 28.9% less in the fibrin-sealant group than in the control group (p = 0.005, 95% confidence limits = 10.2, 43.7). There were no seroconversions in the fibrin-sealant group.Conclusion: These results suggest that fibrin sealant can safely reduce bloody drainage following total knee arthroplasty while maintaining higher hemoglobin levels. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this prospective study was to evaluate the arthroscopic treatment of trochanteric bursitis in patients who have not responded to nonoperative treatment., Methods: Thirty patients were enrolled in this study to evaluate the results of arthroscopic bursectomy. Outcomes were assessed by use of a visual analog pain scale, Harris Hip Score, Short Form 36 Health Survey, and additional specific hip function questions. Patients were given the self-administered outcome questionnaires before surgery and at subsequent follow-up visits. Of the patients, 25 were available for a mean follow-up of 26.1 months (range, 13.8 to 41 months)., Results: Pain scores on the visual analog scale improved from a preoperative mean of 7.2 (0, no pain; 10, worst pain) to a postoperative mean of 3.1 at final follow-up (P = .0001). Mean Harris Hip Scores improved from a mean of 51 preoperatively to 77 at follow-up (P = .0001). Improvements were also noted in the physical component summary scores of the Short Form 36. The mean physical function score improved from 33.6 preoperatively to 54 at follow-up (P = .022), and in the pain category, the mean score improved from 28.7 to 51.5 (P = .001). One postoperative complication occurred, a seroma that required repeat surgery. One patient had a failed arthroscopic bursectomy and subsequently underwent open bursectomy with resolution of symptoms., Conclusions: Arthroscopic bursectomy appears to be an effective option for recalcitrant trochanteric bursitis and is a viable alternative to open bursectomy. In this prospective study patients had good pain relief and improved function compared with their preoperative status. Improvements in a patient's status are usually evident by 1 to 3 months after surgery and appear to be lasting., Level of Evidence: Level IV, therapeutic case series.

The cementless acetabular components used over the past 2 decades have varied in type of ingrowth fixation, supplemental fixation, locking mechanisms, and bearing surface. We evaluated 15-year follow-up results from 2 cementless acetabular components: the Harris-Galante I (HG; Zimmer, Warsaw, IN) and the PCA (Howmedica, Rutherford, NJ), in terms of revision and radiographic loosening. Three of the 120 HG I acetabular components were revised for wear and osteolysis without loosening. Seventeen of the 100 PCA components were revised for aseptic loosening (with or without osteolysis). Including those cases revised, 21 PCA acetabular components were loose radiographically, and no HG I component was loose. At least with these 2 first-generation designs, differences were seen in performance of the acetabular component in terms of revision and loosening at 15 years.

The purpose of this study was to update the results of a prospective series of primary cementless total hip arthroplasties after a minimum of fifteen years of follow-up. It is one of the first studies of cementless total hip arthroplasties followed for a minimum of fifteen years. One hundred consecutive Porous Coated Anatomic (PCA) total hip replacements were implanted between October 1983 and January 1986. Fifty-five patients (sixty-four hips) that were alive at a minimum of fifteen years postoperatively are the focus of the present study. At this time of follow-up, at an average of 15.6 years (range, fifteen to seventeen years) after the total hip arthroplasty, 17% (seventeen hips) of the entire cohort and 23% (fifteen hips) of the living cohort had undergone revision because of loosening of the acetabular component or osteolysis. Seven percent (seven hips) of the entire cohort and 6% (four hips) of the living cohort had undergone revision for loosening of the femoral component or osteolysis. Only four femoral stems had been revised for isolated loosening (without osteolysis). The PCA femoral component proved to be durable at a minimum of fifteen years postoperatively, while the acetabular component was less durable.

One hundred consecutive primary total hip arthroplasties performed with use of a porous-coated anatomic total hip prosthesis, fixed without cement, in ninety-one patients were followed prospectively for a minimum of ten years. At the time of the most recent follow-up, twenty patients (twenty-three hips) had died and seventy-one patients (seventy-seven hips) were living. The average age of the living patients was sixty-six years (range, thirty-two to ninety-two years), and their average Harris hip score was 84 points (range, 33 to 100 points). Twelve percent (nine) of the seventy-seven hips were found to be associated with pain in the thigh when the patients were specifically questioned by the examiner. Eleven hips were revised during the follow-up period. Only the acetabular component was revised in six hips, only the femoral component was revised in one hip, and both the femoral and the acetabular components were revised in four hips. Of the ten acetabular revisions, one was performed because of acute dissociation of the component and eight, because of a combination of polyethylene wear, osteolysis, and loosening; the tenth acetabular revision consisted of exchange of the liner and curettage and bone-grafting of the osteolytic area. Of the five femoral revisions, two were performed because of loosening and three, because of extensive osteolysis of the proximal aspect of the femur. Including the revised components, twelve acetabular components and five femoral components had radiographic evidence of aseptic loosening. Acetabular osteolysis occurred in seventeen hips. Femoral osteolysis occurred in thirty-nine hips: in the proximal aspect of thirty-one hips, in the distal aspect of four, and in both the proximal and the distal aspect of four. The durability of the femoral fixation documented in this study is especially encouraging in view of the fact that this was our initial experience with devices fixed without cement and that a so-called first-generation femoral component was used. However, the study also demonstrated that not all acetabular components fixed without cement function well over the long term and that specific design considerations (adequate initial fixation, congruency between the liner and the shell, an optimum shell-liner capturing mechanism, and a smaller femoral head) are warranted.

Total knee arthroplasty was evaluated in 10 patients with post-traumatic osteoarthrosis secondary to work-related knee injuries (age- and sex-matched with 10 controls who had total knee arthroplasties for nonwork-related osteoarthrosis) to determine if Workers' Compensation status influenced treatment outcome. Using the Hospital for Special Surgery Knee Rating System (maximum possible score: 100), most recent follow-up scores averaged 64.1 for Workers' Compensation patients and 91.9 for controls. Subjective indices (pain, function) were significantly different between groups (p < 0.05), but objective indices (range of motion, strength, deformity, instability) were not. No significant differences were noted between groups on either immediate postoperative or most recent follow-up radiographs (which were assessed for alignment and radiolucencies at implant surfaces, respectively). Suboptimal outcomes can be anticipated in total knee arthroplasties performed on Workers' Compensation patients, particularly in cases where claims have not been settled at the time of surgery.

Although technetium diphosphonate (TcMP) and Indium-111 white blood cell labeled (Ind-WBC) imaging are reported useful in identifying aseptic and septic loosening in cemented hip arthroplasty, their usefulness has not been identified in uncemented porous coated hip arthroplasty. We attempted to define the natural history of TcMP and Ind-WBC imaging in primary P.C.A. uncemented total hip arthroplasty. Twenty-five hips in 21 patients were scanned immediately postoperatively, at 3 months, 6 months, 12 months, 18 months, and 24 months after surgery with both TcMP and Ind-WBC tracers. Clinical and radiographic follow-up were also obtained at each interval. Intensity and distribution of tracer activity were recorded as well as the time when stabilization occurred around the acetabulum, femoral porous surface areas, and femoral stem tip. Acetabular cup and femoral porous surface areas stabilized in the first year on both TcMP and Ind-WBC imaging. Focal femoral hip activity continued at 24 months in 72% of TcMP and 24% of Ind-WBC images. TcMP and Ind-WBC images used to assess uncemented total hip arthroplasty should not be over interpreted. Although persistent intense activity after one year around the acetabulum and porous surface femoral areas should be considered abnormal for both TcMP and Ind-WBC scans, femoral tip activity is present in the majority of patients, with or without thigh pain, at 24 months on TcMP scans. Tip activity can also persist at 24 months on Ind-WBC images and should be interpreted in conjunction with TcMP images.

One hundred consecutive uncemented Porous Coated Anatomic total hip arthroplasties performed in 91 patients who obtained prospective serial clinical and radiographic evaluation during a minimum 7-year followup period were studied for the occurrence, extent, and progression of localized periprosthetic bone loss (osteolysis). Periprosthetic bone loss occurred around the femoral component in 11 hips, the acetabular component in 2 hips, and both components in 2 hips during the followup interval. The bone loss was progressive in 6 hips (2 of 11 femoral cases, 2 of 2 acetabular cases, and 2 of 2 both component cases). It frequently occurred around components that showed no evidence of acetabular migration or femoral subsidence (11 of 15 cases). The average age at surgery of patients in the bone loss group was 10 years younger than the nonbone loss group (in the 100 hip cohort). Clinically, most patients with bone loss were asymptomatic, with the average Harris hip rating of 92.4 points (range, 85-99 points). With this particular device at this interval of followup (7 years), the acetabular and the proximal femoral osteolytic lesions are of greatest concern. Wear of the acetabular component was greater for cases with osteolysis than for those without osteolysis, but the difference was not significant.

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.

Twelve normal greyhound femora were divided into three groups. In group one, femoral stems were placed in neutral position with maximal fill. Group two had undersized femoral stems placed in neutral position. Group three had undersized femoral stems placed in varus position. Intact and implanted femora were loaded from 10 newtons (N) to 300 N in axial compression at a rate of 25 N/s for 10 replications. A strain gauge analysis showed that the strain distribution of all implanted femora were substantially different from intact femora, but femora with large implants placed in neutral position had the least amount of deviation from normal. An undersized stem in neutral position had significantly less compressive longitudinal strains along the proximomedial and proximocranial cortices. An undersized stem in varus position improved implant fit along the proximomedial and distolateral cortices, which resulted in increased tensile hoop strains. There were multiple significant correlations between the strain data and implantation variables (implant alignment, canal fill, and implant fit). Subsidence was significantly greater for the undersized implant in neutral position. There was not a difference in subsidence between the large neutral and varus groups. The most important variable that decreased subsidence was increased lateral implant fit (r = -0.86, P = .0003).

This study reports on the results of the implant and tissue analysis of clinically retrieved hydroxyapatite (HA)-coated implants. Five of the patients with fixed HA-coated stems had been clinically diagnosed with osteolysis. The semiquantitative histologic grading in these patients showed HA, polyethylene, and metal particles were all present (Grade 3+) in the osteolytic regions of the periprosthetic tissue. Additionally, inflammatory cells (Grade 3+) were present in these regions. Back-scattered electron (BSE) and correlated elemental analysis showed HA particulate was present in the polyethylene inserts. The HA could be distinguished from bone chips in the polyethylene based on morphology and anatomic number gray level differences. This study was limited in that no clinical results of particular HA-coated implant series were reported. Careful follow-up care in patients with coated devices is recommended.

The results of 100 primary arthroplasties with a porous-coated anatomic total hip prosthesis that were performed consecutively in ninety-one patients were followed prospectively for five to seven years after the operation or until death. Clinical Harris hip ratings and anteroposterior and lateral radiographs were made preoperatively, several times in the first postoperative year, and at annual intervals thereafter. Average sequential hip ratings were maintained between 92 and 93 points during the follow-up interval. Pain in the thigh, which did not limit function, was recorded at the yearly examinations from the first to the fifth year. After one year, 18 per cent of the thighs were painful, and in succeeding years, 19 per cent, 23 per cent, 26 per cent, and 15 per cent were painful. Radiographs demonstrated that the fixation of the femoral component was by ingrowth of bone in 94 per cent of the hips, by stable fibrous fixation in 1 per cent, and by unstable fibrous fixation in 5 per cent, according to the criteria of Engh et al. By five years, 6 per cent of the acetabular components had migrated, and 5 per cent of the femoral components had subsided. Two acetabular components had been revised, and one revision of a femoral component was pending. The evaluated device was an early-generation prosthesis that was designed for insertion without the use of cement. Further study is necessary to determine the long-term durability of the prosthesis-bone interface.

The results of the first and second groups of 50 consecutive primary, uncemented porous-coated anatomic arthroplasties were analyzed to evaluate the learning curve associated with the procedure. Femoral fit, acetabular cup angle, femoral fracture rate, minimum two-year clinical hip ratings, and clinical symptoms were compared between the two groups. Significant improvement in achieving better femoral canal filling with the prosthesis and lower acetabular cup angle placements was documented in the second 50 cases. Although a definite learning curve in mastering the technique of uncemented total hip arthroplasty was observed, thigh pain rate and clinical ratings were not improved after two years.

Although few studies address the use of three-phase bone scanning (TPBS) and indium-111-labeled white blood cell scintigraphy (111In-WBC) in hip arthroplasty utilizing a porous-coated prosthesis, the literature suggests that scintigraphic patterns in the uncomplicated patient may differ form that seen with the cemented prosthesis. In an attempt to determine the scintigraphic natural history, 25 uncomplicated porous-coated hip arthroplasties in 21 patients were prospectively studied with serial TPBS and 111In-WBC at approximately 7 days, and 3, 6, 12, 18, and 24 mo postoperatively. This report deals with findings related to the acetabulum. All 25 prostheses (144 of 144 scans) demonstrated increased uptake on the bone-phase images. Although this activity decreased with time, 76% had persistent uptake at 24 mo. Twenty-three of 25 prostheses (126 of 140 scans) showed increased uptake on 111In-WBC scintigraphy, invariably decreasing with time, but with 37% having significant uptake at 24 mo. Scintigraphic patterns in the uncomplicated porous-coated hip arthroplasty patient appear to differ from patterns described in cemented prostheses.

Fifty uncemented porous-coated total hip prostheses were implanted in forty-seven patients whose mean age was fifty-eight years. Clinical hip-rating scores, as described by Harris, were determined and anteroposterior and frog-leg lateral radiographs were made preoperatively, shortly postoperatively, and at three months, six months, one year, and two years postoperatively. The mean hip-rating score was 92 points (range, (range, 74 to 100 points) at one year and 92 points (range, 69 to 100 points) at two years. The thigh was slightly painful in nine patients (18 per cent) at one year and in eight (16 per cent) at two years. Fourteen hips (28 per cent) (in thirteen patients) caused a moderate or severe limp two years postoperatively; however, this complication appears to have been related more to the direct lateral approach that was used than to the prosthesis. Six (13 per cent) of the patients walked with a cane at one year and five (11 per cent) still required a cane at two years. Serial radiographic evaluations revealed that, between the first and second postoperative years, a progressive radiodense femoral line developed in twenty hips (41 per cent); a progressive acetabular line, in four hips (8 per cent); and progressive femoral sclerosis, in twelve hips (24 per cent). There was progressive loosening of beads from twelve (24 per cent) of the femoral components and from nine (18 per cent) of the acetabular components. The position of one acetabular and one femoral component changed. Two femoral shafts fractured, one intraoperatively and one fourteen months postoperatively. We concluded that the clinical results were encouraging in these patients at the end of two years. We are concerned, however, about the progressive radiodense lines, sclerosis, and loosening of beads as well as the slight, but persistent, pain in the thigh in eight patients.

We retrospectively analyzed a program of prior deposit and storage of autologous blood that was used for patients who underwent elective orthopaedic procedures over a period of thirty-six months at the Walter Reed Army Medical Center. Of a total of 211 patients who underwent total joint replacement or spinal fusion during this period and who had sufficient records to be included in the study, a total of 159 patients enrolled in the program. The fifty-two patients who did not enroll in the study, twelve of whom were rejected because of medical problems, served as a control group. Since the preoperative hematocrit values for patients in the group that received autologous blood were similar to those for the control group, multiple preoperative phlebotomies in these patients, who had received supplemental iron, did not seem to have any deleterious effects. One hundred and thirteen (71 per cent) of the 159 patients who were enrolled in the program received only autologous blood. The remaining forty-six patients required homologous blood also, but 64 per cent of their transfusion needs were provided by autologous blood. The only reactions to the transfusions in the study were in four patients who received homologous blood. We think that a program of prior deposit and storage of autologous blood should be an option for patients who are to undergo elective orthopaedic surgery. Such a program is well tolerated by the patients and easily managed by the staff, and it was not difficult to implement at our tertiary referral hospital.

The purpose of this study was to prospectively determine what effect total joint arthroplasty had on the myocardial-associated isoenzymes of serum creatine kinase (CK-MB) and lactate dehydrogenase (LD-1:LD-2). Fifty patients treated with total joint arthroplasty of the hip or knee had isoenzyme determinations using automated spectrophotometry and agarose gel electrophoresis. Skeletal muscle injury associated with the trauma of surgery resulted in significant elevations of the absolute value of CK-MB; however, the percentage of CK-MB comprising total CK activity and LD-1:LD-2 did not rise significantly in patients who did not experience postoperative myocardial infarction. It is important to determine both serum CK-MB and LD-1:LD-2 in suspected postoperative myocardial infarction since false positive elevations of CK-MB can occur. Elevations of CK-MB exceeding 50 International Units/liter or 5% of the total CK activity combined with LD-1:LD-2 exceeding 1.0 should not be attributed to skeletal muscle injury alone following total joint arthroplasty of the hip or knee.

Although few reports address the use of three-phase bone scanning (TPBS) and 111In-labeled white blood cell (In-WBC) scintigraphy in hip arthroplasty utilizing a porous coated prosthesis, the literature suggests that scintigraphic patterns in the uncomplicated patient may differ from that seen in the cemented prosthesis. In an attempt to determine the scintigraphic natural history, 25 uncomplicated porous coated hip arthroplasties in 21 patients were prospectively studied with serial TPBS and In-WBC at approximately 7 days, and at 3, 6, 12, 18, and 24 mo postoperatively. This report deals with findings related to the prosthetic tip. Only one of 136 flow studies were abnormal and only two of 136 blood-pool images demonstrated focally increased activity. All 25 prostheses (120 of 143 scans) demonstrated increased uptake on the bone phase images. The area about the tip was divided into three segments; increased uptake at 24 mo was noted in the medial, distal, and lateral segments in 16%, 72%, and 56% of prostheses, respectively. Twenty of 25 prostheses (82 of 142 scans) showed uptake on In-WBC scintigraphy, being noted in 48% of prostheses at 24 mo. We conclude that scintigraphic patterns in the uncomplicated patient with a porous coated prosthesis appear to differ from patterns described in cemented prostheses.

Ipsilateral femur fractures in patients who have had cemented total hip arthroplasty is an infrequent and hazardous complication. Operative treatment has been specifically recommended for type II fractures (those extending from the proximal portion of the femur shaft to beyond the distal tip of the prosthesis) because of the predictably unsatisfactory results with nonoperative treatment. The authors report the successful nonoperative treatment of a postoperative fracture around an uncemented porous-coated femoral component. They recommend nonoperative treatment for minimally displaced type II femoral shaft fractures around uncemented porous-coated prostheses.

Since indium-111 white blood cell (In-111 WBC) scintigraphy is often used to evaluate for osteomyelitis in bone fractures, it is important to know if noninfected fractures have In-111 WBC uptake. Twenty-seven noninfected closed fracture sites in 19 patients were prospectively evaluated with technetium-99m methylene diphosphonate bone scintigraphy and In-111 WBC scintigraphy. In-111 WBC uptake was present in 41% of the 27 sites. In the 11 positive sites, the In-111 WBC uptake was 1+ (definite but minimal) in 55%, 2+ (moderate) in 36%, and 3+ (marked) in 9%. The visual intensity of the radioactive uptake on In-111 WBC scintigrams relative to that on bone scintigrams was less in 82%, equal in 9%, and greater in 9%. The visual size of the area of uptake on In-111 WBC scintigrams and bone scintigrams was smaller in 36%, equal in 55%, and greater in 9%. Factors that may help distinction of In-111 WBC uptake due to fracture alone from infection associated with fracture are discussed.

Scintigraphy with indium-labeled white blood cells has been reported to be sensitive and specific in the diagnosis of low-grade sepsis of the musculoskeletal system. We reviewed the records of fifty patients who had suspected osteomyelitis or suspected infection about a total joint prosthesis and who underwent scintigraphy with technetium-99m methylene diphosphonate and scintigraphy with indium-111 oxine-labeled white blood cells before an open surgical procedure. Any patient who received preoperative antibiotics was not included in the study. For all of the patients, gram-stain examination of smears, evaluation of a culture of material from the operative site, and histological examination were done. The patients were divided into two groups. Group I was composed of twenty-four patients, each of whom had a prosthesis in place and complained of pain. Group II was composed of twenty-six patients for whom a diagnosis of chronic osteomyelitis had to be considered. With the indium scans alone, there was only one false-negative result (in Group II), but there were eighteen false-positive results (eight patients in Group II and ten patients in Group I). Although scintigraphy with indium-labeled white blood cells is quite sensitive, it is not specific in detecting chronic osteomyelitis; a negative scan should be considered highly suggestive that osteomyelitis is not present. Specificity can be increased by interpreting the indium scan in conjunction with the technetium scan.

Magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) examinations were compared for detection of femoral head osteonecrosis. Of 29 hips with clinical and roentgenographic evidence of osteonecrosis (18 histologically confirmed), 15 were Stage II, three transitional, six Stage III, and five Stage IV. MRI identified osteonecrosis in all 29 cases (100% sensitivity), and there were no false-positives (100% specificity). Of 24 osteonecrotic hips with technically adequate examinations, SPECT identified 14 (sensitivity 58%), and there were four false-positives (78% specificity). If Stages III and IV were eliminated, SPECT correctly identified ten of 15 (67% sensitivity).

Thirty consecutive patients who underwent double contrast CT arthrography prior to shoulder arthroscopy were prospectively studied. Results from both studies were recorded with the radiologist blinded to the arthroscopic findings when making the final CT reading. The sensitivity, specificity, and accuracy, respectively, of CT arthrography findings compared to arthroscopy were 50%, 100%, 96% for rotator cuff; 66%, 100% 96% for bicipital labral complex; 100%, 100%, 100% for loose bodies; 50%, 100% 93% for Hill-Sachs lesions; 90%, 73%, 83% for anterior labral defects; and 100%, 100%, 100% for posterior labral defects. We conclude that shoulder arthroscopy accurately delineates abnormalities of the anterior and posterior labrum, bicipital labral complex, rotator cuff, joint synovium, and humeral head. CT arthrography accurately delineates capsular redundancy, loose bodies, hardware around joints, and bony glenoid rim abnormalities.

The results of selective magnetic resonance imaging of the knee were compared with those of arthroscopy in a prospective series of fifty patients. A specifically designed protocol for imaging, producing T1 sagittal images interleaved at four millimeters while the patient's foot was in 20 degrees of external rotation, was utilized. This technique, called selective magnetic resonance imaging, yielded excellent visualization of the posterior cruciate ligament, medial meniscus, and lateral meniscus in all patients. However, in only 76 per cent of the patients was the anterior cruciate ligament well visualized. Compared with arthroscopy, the sensitivity, specificity, and accuracy of selective magnetic resonance imaging were, respectively, 95.8, 100, and 98 per cent for tears of the medial meniscus; 66.7, 95.1, and 90 per cent for tears of the lateral meniscus; undefined, 100, and 100 per cent for tears of the posterior cruciate ligament; and 100, 96.9, and 97.3 per cent for tears of the anterior cruciate ligament, when that ligament was well visualized. Our selective sequence can be performed in fifteen minutes at a cost that is comparable with that of arthrography. It is totally non-invasive and requires no exposure to ionizing radiation. Selective magnetic resonance imaging can be a safe and valuable adjunct to the clinical evaluation of the knee and an aid to efficient preoperative planning.