A prospectively randomized double-blind study on the effect of initial graft tension on knee stability after anterior cruciate ligament reconstruction

BACKGROUND: No consensus exists on the amount of tension that should be applied to anterior cruciate ligament grafts to best facilitate graft incorporation and re-create normal knee mechanics. HYPOTHESIS: Differences in initial graft tension will affect postoperative knee stability. STUDY DESIGN: Prospective, randomized, double-blind clinical trial. METHODS: Forty-nine patients undergoing bone-patellar tendon-bone autograft anterior cruciate ligament reconstruction by a single surgeon were randomized into high-tension (n = 27) and low-tension (n = 22) groups. Grafts were set at 90 N or 45 N. Arthrometric measurements (KT-1000 arthrometer manual maximum) of anterior tibial displacement and knee range of motion were made before surgery and at 1 week and an average of 20 months after surgery. Knee outcome scores were collected before and after surgery, and a single-leg hop test was also performed at final follow-up. RESULTS: After anterior cruciate ligament reconstruction, anterior tibial displacement was significantly greater in the patients in the low-tension group (P < .05). The side-to-side difference in anterior tibial displacement in the high-tension and low-tension groups was 1.1 +/- 1.7 mm versus 2.4 +/- 2.4 mm 1 week after surgery and 2.2 +/- 1.6 mm versus 3.0 +/- 2.2 mm at follow-up. Five patients had abnormal anterior tibial displacement (>5 mm side-to-side difference), and all were in the low-tension group (P <.05). Knee outcome scores improved with surgery (P <.01), with similar results for low-tension and high-tension groups. Hop test deficits were not different between groups. CONCLUSIONS: Initial graft tension affects the restoration of knee stability. A graft tension of 45 N was not sufficient for restoring knee stability.     

Three-phase bone scan pattern in asymptomatic uncemented total knee arthroplasty

In this study we investigated the bone scan pattern in a homogeneous group of asymptomatic patients implanted with the same type of total knee arthroplasty (TKA) and with a minimum follow-up of 2 years. Twenty-nine patients (21 females, 8 males, mean age 62 years), with a total of 30 uncemented Hofmann TKAs, were entered in the study. The time interval from surgery to scintigraphic evaluation ranged from 2 to 4 years. Bone scan was performed using the three-phase technique and images were interpreted by visual analysis using a three-point scale for the dynamic and blood pool phases and a five-point scale for the bone phase. Areas of increased periprosthetic technetium-99m methylene diphosphonate (MDP) uptake were observed until 4 years after surgery. However, comparing the TKAs implanted 2, 3 and 4 years previously, a decreasing pattern in tracer uptake intensity was noted this being more evident in the femoral and lateral tibial components. In some cases, a persistently elevated tracer uptake, not exceeding a moderate grade, was found in the medial tibial component. In conclusion, increased periprosthetic^99mTc-MDP uptake is a common finding in asymptomatic uncemented Hofmann TKAs for a prolonged period after surgery, but the uptake intensity is generally mild or moderate and shows a characteristic decreasing pattern over time. Furthermore, in contrast with other types of asymptomatic knee implants previously investigated, no case of high or very high bone uptake was recorded with this type of implant. We may speculate that scintigraphic parameters of normality, and pathology, should be determined for each type of TKA. It is likely that, with the uncemented Hofmann TKA, a high or very high tracer uptake or a progressive increase in the uptake intensity is suggestive of the presence of complications.     

Computerized tomography assessment of femoral and tibial rotation in total knee prosthesis

PURPOSE: CT assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty. MATERIAL AND METHODS: January to July 1999, seventeen patients, 10 males and 7 females, mean age 66 years (standard deviation +/- 4) were examined after total knee arthroplasty. Exclusion criteria were prosthesis loosening and severe (equal or superior to 7 degrees) varus or valgus deviation. All patients were examined with knee radiography in the standing position completed by axial projections of patella and by CT scanning. We used a modification of Berger technique and carried out comparative CT scans extended lower limbs and acquisitions perpendicular to the mechanical axis of the knee, from the femoral supracondylar region down to the plane crossing the distal end of the tibial prosthetic component. Reference lines were then drawn electronically on given scanning planes to reckon the axial deviation of the femoral and tibial prosthetic components. RESULTS: Six patients, one female and 5 males, with normal rotational values of femoral and tibial prosthetic components presented no clinical symptoms. Eight patients, 4 females and 4 males, with abnormal values presented the following clinical symptoms: medial impingement, (incomplete) dislocation patella, and lateral instability. One female patient with a normal rotational value of femoral prosthetic component and an altered value of tibial prosthetic component presented medial impingement. Finally two patients, one female and one male, were absolutely asymptomatic although the rotational values of the two prosthetic components were beyond the normal range. CONCLUSIONS: Total knee arthroplasty is presently a standard treatment for many conditions involving this joint. There are several possible postoperative complications, namely fractures, dislocations (a)septic loosening and femoropatellar instability. The latter condition is the most frequent complication among implant failures and is caused by bad orientation of the femoral and tibial components on frontal and axial planes. We measured the orientation of the prosthetic components introducing a CT procedure which modifies the uniarticular with four scans introduced by Berger. The new method uses Berger's parameters and the CT study of both joints by means of Helical CT. With a single examination lasting less than 4 minutes and with the patient in a more comfortable position, we can obtain: 1) comparative and simultaneous assessment of the contralateral joint; 2) several scans to better define Berger's parameters and to accomplish measurement of the rotational deviation with higher precision and markedly decreasing the error margin. The analysis of the results confirms the international literature findings and especially the fundamental importance in positioning both prosthetic components within normal values, as emphasized by the relationship between the clinical symptoms and the rotational degree of the femoral and tibial prosthetic components.     

Evaluation of (99m)Tc-ciprofloxacin scintigraphy in a rabbit model of Staphylococcus aureus prosthetic joint infection.

Ciprofloxacin, a quinolone antibiotic drug, binds to DNA topoisomerase IV and DNA gyrase of various bacteria. Thus ciprofloxacin labeled with (99m)Tc could potentially act as a specific marker allowing discrimination between infection and sterile inflammation. We evaluated these properties on a rabbit model of prosthetic joint infection previously validated. We compared the images obtained in 2 groups of animals: rabbits with infected (G1; n = 6) and uninfected (G2; n = 7) prosthesis. METHODS: Partial right-knee arthroplasty was performed on 13 New Zealand White female rabbits, with a tibial silicone-elastomer implant fitting into the intramedullary canal of the tibia. After the surgical wound was closed, 10(7) cfu of a clinical strain of methicillin-susceptible Staphylococcus aureus were injected into the joint in G1 rabbits. G2 rabbits were injected with sterile saline. No antibiotic therapy was given to the animals. (99m)Tc-ciprofloxacin planar imaging was performed on days 5, 12, and 19 after surgery, and after 3 mo in 1 uninfected rabbit. Images were obtained 1, 4, and 24 h after injection (147 +/- 13 MBq). RESULTS: In G1, increased right knee (99m)Tc-ciprofloxacin uptake was observed in 3 of 5 rabbits on day 5, and in all cases on days 12 and 19. Killing of the animals revealed purulent arthritis, osteitis, and tibial myelitis. In G2, significant right-knee uptake was found on days 12 and 19 in 5 of 6 rabbits, and after 3 mo in 1; all sets of images were negative in 1 animal. Bacteriologic studies after the animals were killed were negative in G2. Mean right/left knee uptake ratios on day 19 (4-h images) were 1.8 +/- 0.4 in G1 versus 1.4 +/- 0.3 in G2 (not significant). Late images did not discriminate between infected and uninfected arthroplasty. CONCLUSION: Results of (99m)Tc-ciprofloxacin imaging in rabbits with infected/uninfected knee prosthesis suggest good sensitivity but lack of specificity for the detection of S. aureus infection.     

dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) indicates adaptive capacity of human knee cartilage.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T1-relaxation time measurements after penetration of the hydrophilic contrast agent Gd-DTPA(2-). This study compares dGEMRIC in age-matched healthy volunteers with different levels of physical activity: Group 1 (n = 12): nonexercising individuals; Group 2 (n = 16): individuals with physical exercise averaging twice weekly; Group 3 (n = 9): male elite runners. dGEMRIC was performed 2 hr after an intravenous injection of Gd-DTPA(2-) at 0.3 mmol/kg body weight. T1 differed significantly between the three different levels of physical exercise. T1 values (mean of medial and lateral femoral cartilage) for Groups 1, 2, and 3 were: 382 +/- 33, 424 +/- 22 and 476 +/- 36, respectively (ms, mean +/- SD) (P = 0.0004, 1 vs. 2 and 0.0002, 2 vs. 3). Irrespective of the exercise level, T1 was longer in lateral compared to medial femoral cartilage (P = 0.00005; n = 37). In conclusion, this cross-sectional study indicates that human knee cartilage adapts to exercise by increasing the glycosaminoglycan content. Furthermore, results suggest a compartmental difference within the knee with a higher glycosaminoglycan content in lateral compared to medial femoral cartilage. A higher proportion of extracellular water, i.e., larger distribution volume, may to some extent explain the high T1 in the elite runners.     

Bone injury associated with anterior cruciate ligament and meniscal tears: assessment with bone single photon emission computed tomography

RATIONALE AND OBJECTIVES: Acute injury of the menisci and ligaments about the knee joint is often associated with accompanying bone injury. The role of bone single photon emission computed tomography (SPECT) was assessed in this clinical setting. MATERIALS AND METHODS: Knee SPECT was performed in 94 patients with suspected ACL, meniscal tear, or both and was correlated with arthroscopy (n = 74), magnetic resonance imaging (MRI) (n = 37), or both. Scintigraphic findings were categorized based on their anatomic location and on uptake intensity (0-3 grade scale). RESULTS: Correlation with arthroscopy: Eleven patients had a normal arthroscopy of which in 10, SPECT images detected no abnormality. Sixty-three patients had abnormal arthroscopic findings, whereas all had abnormal SPECT studies. Thirty-eight patients had an anterior cruciate ligament (ACL) tear on arthroscopy. In this type of injury SPECT images detected increased uptake in the posterior aspect of the lateral tibial plateau (LTPp) with a positive predictive value (PPV) of 93% and a negative predictive value (NPV) of 97%. In 55% of the patients, increased uptake was also detected in the region of the middle sulcus of the lateral femoral condyle (LFCm): a "kissing" pattern. Tear of the medial meniscus was diagnosed by arthroscopy in 43 patients. SPECT images detected increased uptake in the medial tibial plateau (MTP) with a PPV of 78% and a NPV of 83%. Correlation with MRI: all seven cortical fractures seen on MRI were detected on SPECT. Twenty-eight patients had MRI findings suggestive of an ACL injury. Accompanying bone bruises were seen in 18 of them (64%). On SPECT images, all 28 patients with an ACL tear had increased uptake in the LTPp. Intensity of uptake in patients with associated bone bruise, however, was significantly higher; mean intensity grade 2.4 +/- 0.7 in case of accompanying bone bruise compared with 1.4 +/- 0.8 in case of an ACL tear without associated bone injury, P< 0.01. CONCLUSION: Results of the study suggest that bone SPECT is valuable in acute knee trauma for assessment of ACL, meniscal tears, or both and for detection of associated bone injury.     

Transparent 3-dimensional CT in evaluation of femoral bone tunnel communication after ACL double-bundle reconstruction: comparison between outside-in and transportal technique

Purpose

The purpose of this study is to assess the incidence of post-operative femoral bone tunnel communication after anterior cruciate ligament double-bundle reconstruction (ACL-DBR) with two drilling techniques by transparent 3-dimensional computed tomography (CT) and elucidate the factors associated with post-operative femoral bone tunnel communication.

Methods

Fifty-five patients underwent ACL-DBR using outside-in technique (Group A, 25 patients) and transportal technique (Group B, 30 patients) for the drilling of femoral tunnel. CT was taken at 1 week and 6 months post-operatively. The femoral and tibial bone tunnel orientation, position, the divergency and the distance of bone bridge between the tunnels were measured using reconstructed CT images. In order to identify the factors related to post-operative femoral bone tunnel communication, patients were divided into two groups depending on whether femoral bone tunnels communicated (Group F–C) or remained (Group F–R) at 6 months post-operatively.

Results

Femoral bone tunnels in Group B were orientated horizontally and dorsally compared to those in Group A. Tunnel divergency between two femoral tunnels was greater in Group A (11.7°) than in Group B (10.0°). Average distance of bone bridge at 1 week post-operatively was 1.8 mm in Group A and 1.7 mm in Group B (n.s.). Post-operative femoral bone tunnel communication occurred in 16 patients (64 %) in Group A and in 18 patients (60 %) in Group B at 6 months after ACL-DBR, respectively (n.s.). Regarding tibial tunnels, there were no significant differences in tunnel orientation, position, divergency and incidence of post-operative tibial tunnel communication between Groups A and B. Mean distance of femoral bone bridge at 1 week in Group F–R (2.5 mm) was significantly greater than in Group F–C (1.3 mm) (p < 0.001).

Conclusions

There was no significant difference in the incidence of post-operative femoral tunnel communication between two techniques. To avoid post-operative femoral tunnel bone communication, more than 2 mm distance of bone bridge at surgery is recommended.

Level of evidence

Retrospective comparative study, Level III.     

Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee

BACKGROUND: Knee kinematics and in situ forces resulting from anterior cruciate ligament reconstructions with 2 femoral tunnel positions were evaluated. HYPOTHESIS: A graft placed inside the anatomical footprint of the anterior cruciate ligament will restore knee function better than a graft placed at a position for best graft isometry. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were tested in response to a 134-N anterior load and a combined 10-N.m valgus and 5-N.m internal rotation load. A robotic universal force-moment sensor testing system was used to apply loads, and resulting kinematics were recorded. An active surgical robot system was used for positioning tunnels in 2 locations in the femoral notch: inside the anatomical footprint of the anterior cruciate ligament and a position for best graft isometry. The same quadrupled hamstring tendon graft was used for both tunnel positions. The 2 loading conditions were applied. RESULTS: At 30 degrees of knee flexion, anterior tibial translation in response to the anterior load for the intact knee was 9.8 +/- 3.1 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 13.8 +/- 4.6 mm; position 2: 16.6 +/- 3.7 mm; P < .05). There was a significant difference between the 2 tunnel positions. At the same flexion angle, the anterior tibial translation in response to the combined load for the intact knee was 7.7 +/- 4.0 mm. Both femoral tunnel positions resulted in significantly higher anterior tibial translation (position 1: 10.4 +/- 5.5 mm; position 2: 12.0 +/- 5.2 mm; P < .05), with a significant difference between the tunnel positions. CONCLUSION: Neither femoral tunnel position restores normal kinematics of the intact knee. A femoral tunnel position inside the anatomical footprint of the anterior cruciate ligament results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry. CLINICAL RELEVANCE: Anatomical femoral tunnel position is important in reproducing function of the anterior cruciate ligament.     

Effects of position and speed on joint torques and knee shear after ACL injury.

PURPOSE: The purpose of this study was to assess the effect of joint position and movement speed on hip (HT) and knee (KT) extensor torque, HT/KT ratio (HKR), and anterior tibial shear (S) in presurgical-ACL deficient (PRE; N = 15), post-ACL reconstructed (POST; N = 15), and uninjured controls (CON; N = 15). METHODS: Measurements were recorded on a semirecumbent variable resistance, closed-chain dynamometer. Tests were conducted at 1 and 1.5 Hz and maximum speed at 33% and 50% 1RM. HT, KT, and S were recorded during the extension phase of the cycle (85 degrees -25 degrees of knee flexion). RESULTS: KT was greatest when the knee was more flexed, whereas HT dominated when it was more extended. This suggests that the hamstrings, as a component of the hip extensors, may generate considerable propulsive force during knee extension, which may help counter anterior tibial shear. S increased whereas KT decreased, suggesting that the quadriceps continue to generate shear force despite the decreasing mechanical advantage producing KT. Increasing knee extension speed significantly decreased S in the POST and CON groups. The correlations between KT and S changed from significantly negative to significantly positive as the knee extended from 85 degrees to 25 degrees in the POST and CON groups. This may be related to the orientation of the patellar tendon, relative to the tibial longitudinal axis that shifts from a posterior to anterior direction, as the knee extends. CONCLUSIONS: Joint position and movement speeds affect the magnitude of hip and knee torques and anterior tibial shear. Reducing the magnitude of S during heavy loads may be a normal phenomenon, and POST surgical subjects may retain or regain this function by 1 yr after surgery.     

Severe metallosis after unicompartmental knee arthroplasty

We report on a case of a patient who had femoral osteolysis and severe metallosis of the knee joint resulting from the secondary abrasive wear of the metal-backed tibial component of a unicompartmental knee arthroplasty due to massive wear of tibial polyethylene. The failure was diagnosed 11 years after implantation. This metallosis affected the intra-articular tissues and the subchondral bone.     

99mTc(V)-DMSA seintigraphy in monitoring the response of bone disease to vitamin D3 therapy in renal osteodystrophy

Renal osteodystrophy (ROD) is a common and serious complication for uremic patients and patients are treated with 1,25-dihydroxyvitamin D3. The bone scanning agent 99mTc-phosphate has also been used to evaluate in ROD but it is not clear that bone scintigraphy has a role in the follow-up of treatment. In this study 99mTc(V)-DMSA scintigraphy was performed in eleven patients [age 40.7 +/- 17.3 (mean +/- SD) yr] with ROD before and after vitamin D3 therapy. Images were obtained after hemodialysis performed following tracer injection to maintain normal blood levels of the radiopharmaceutical and to reduce soft tissue activity. Lumbar vertebra-to-soft tissue uptake ratios (LUR) were quantified with the planar 99mTc(V)-DMSA images. Alkaline phosphatase and parathyroid hormone levels after treatment had significantly decreased compared with pre-therapy. In all patients there was visually decreased uptake in bone structures after treatment. After treatment the mean LUR ratio was significantly lower than those of before treatment (3.59 +/- 2.63 vs. 1.65 +/- 0.62; p = 0.01). LUR values were correlated with pre-therapy alkaline phosphatase and parathyroid hormone. These findings indicate that 99mTc(V)-DMSA scintigraphy is sensitive in evaluating the response of ROD to vitamin D3 therapy.     

加压交锁髓内钉治疗下肢长骨干骨折不愈合及延迟愈合

目的 分析下肢长骨干骨折不愈合及延迟愈合的原因,评价加压交锁髓内钉治疗下肢长骨干骨折不愈合及延迟愈合的效果. 方法 1998年2月-2006年12月,对21例股骨和胫骨干骨折不愈合及延迟愈合者采用加压交锁髓内钉治疗.其中股骨13例,胫骨8例,3例未植骨,仅扩髓加压,5例同时行膝关节松解. 结果 随访11.4～36个月,平均13.6个月,全部患者均骨性愈合,平均愈合时间8.7个月,无畸形、感染及再骨折出现.采用Klemm分级标准,优19例,良2例. 结论 下肢长骨干骨折不愈合及延迟愈合主要原因是手术适应证选择不当,手术内固定使用不当,断端血运和骨折愈合生物环境破坏.加压交锁髓内钉治疗下肢长骨干骨折不愈合及延迟愈合具有固定可靠,便于膝、踝早期功能活动,肢体可早期负重等优点.手术应用联合骨移植,扩髓及膝关节松解,可促进骨愈合,改善膝关节功能.     

Knee stability and graft function after anterior cruciate ligament reconstruction: a comparison of a lateral and an anatomical femoral tunnel placement

BACKGROUND: Locations of femoral tunnels for anterior cruciate ligament replacement grafts remain a subject of debate. HYPOTHESIS: A lateral femoral tunnel placed at the insertion of the posterolateral bundle of the anterior cruciate ligament can restore knee function comparably to anatomical femoral tunnel placement. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were subjected to the following external loading conditions: (1) a 134-N anterior tibial load and (2) combined rotatory loads of 10-N.m valgus and 5-N.m internal tibial torques. Data on resulting knee kinematics and in situ force of the intact anterior cruciate ligament and anterior cruciate ligament graft were collected using a robotic/universal force-moment sensor testing system for (1) intact, (2) anterior cruciate ligament-deficient, (3) anatomical double-bundle reconstructed, and (4) laterally placed single-bundle reconstructed knees. RESULTS: In response to anterior tibial load, anterior tibial translation and in situ force in the graft were not significantly different between the 2 reconstructions except at high knee flexion. For example, at 90 degrees of knee flexion, anterior tibial translation was 6.1 +/- 2.3 mm for anatomical double-bundle reconstruction and 7.6 +/- 2.6 mm for laterally placed single-bundle reconstruction (P < .05). In response to rotatory loads, there were no significant differences between the 2 reconstruction procedures (4.8 +/- 2.4 mm vs 4.8 +/- 3.0 mm in anterior tibial translation at 15 degrees of knee flexion, P > .05). CONCLUSION: Lateral tunnel placement can restore rotatory and anterior knee stability similarly to an anatomical reconstruction when the knee is near extension. However, the same is not true when the knee is at high flexion angles. CLINICAL RELEVANCE: To reproduce the complex function of the anterior cruciate ligament, reproducing both bundles of the anterior cruciate ligament may be necessary.     

Self-reported patient outcomes after ACL reconstruction with allograft tissue

PURPOSE: Self-reported outcomes after primary ACL reconstruction using allograft tissues were compared at > or = 5 yr (group 1) and at 2-4 yr (group 2) after surgery. METHODS: The IKDC Subjective Knee Evaluation and Current Health Assessment and the Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS) and the Sports Activity Scale (KOS-SAS) were mailed to 335 consecutive former patients at > or = 2 yr after surgery. RESULTS: Surveys were completed and returned by 64.6% of former patients. Time after surgery for group 1 (N = 90) and group 2 (N = 116) was 7.8 +/- 2.7 and 2.8 +/- 0.8 yr, respectively. Groups did not differ for IKDC Subjective Knee Evaluation or KOS-ADLS scores, although group 1 displayed a lower mean KOS-SAS score. Pooled IKDC Subjective Knee Evaluation scores were 42.7% normal (A), 22.8% nearly normal (B), 24.8% abnormal (C), or 9.7% severely abnormal (D). Pooled standardized IKDC Subjective Knee Evaluation z scores were -0.80 +/- 1.4 standard deviations below the reported population mean for unimpaired individuals with 33.5% scoring at or above the normative population mean, 28.2% scoring < 1 standard deviation below the normative population mean, 18.8% scoring between 1 and 2 standard deviations below the normative population mean, and 19% scoring > or = 2 standard deviations below the normative population mean. Pooled KOS-ADLS scores were 62.1% (> or = 90%), 18% (89-80%), 10.2% (79-70%), and 9.7% (< 70%). Pooled KOS-SAS scores were 49.5% (102/206, > or = 90%), 25.7% (53/206, 89-80%), 9.7% (20/206, 79-70%), and 15.1% (31/206, < 70%). Groups displayed comparable knee function before injury and at the time of the survey. Pooled knee-function scores decreased from 9.5 +/- 1.6 before injury to 8 +/- 2.5 current function (84% return). Both groups displayed decreases in current sports activity level from strenuous to moderate and frequency from 4-7 to 1-3 times per week. CONCLUSIONS: Self-reported outcomes did not differ between groups for the IKDC Subjective Knee Evaluation or for the KOS-ADLS score, although group 1 displayed decreased mean KOS-SAS scores, suggesting decreased perceived sporting activity knee function at > or = 5 yr after surgery. Decreased sports activity level and frequency are comparable with self-reported outcome studies after primary ACL reconstruction using autograft tissues.     

Bone mineral density of the proximal tibia relates to axial torsion in the lower limb

This study sought to determine the relationship between bone mineral density distribution in the proximal tibia and tibial and femoral torsions, hip-knee-ankle angle, hip rotation index (internal-external rotation), knee abduction moments, and the foot progression angle. Simple linear regression found that the hip rotation index (r=-0.59, p<0.001), tibial torsion (r=-0.41, p=0.004), and knee abduction moments (r=0.39, p=0.005) were significantly related to medial-lateral BMD ratio for all subjects. The three variables were then studied together to determine their relationship to the bone mineral distribution in the proximal tibia using multiple linear regression (r=0.80, p<0.001). These findings suggest that higher medial knee joint loads, loss of internal rotation of the hip, and internal tibial torsion may lead to increased medial versus lateral BMD of the proximal tibia of healthy knees. Similar bone distribution patterns are found in knees with osteoarthritis; therefore, we suggest these may be risk factors.     

Quantitative analysis of radiophosphate uptakes in asymptomatic porous-coated hip endoprostheses

A quantitative analysis of the uptake of radiophosphate adjacent to the femoral component of a porous-coated cementless prosthesis was undertaken in asymptomatic patients in order to establish normal temporal changes. The group consisted of 55 patients with 62 arthroplasties of 1.6-49-mo duration. Ratios of the stem, stem tip, greater trochanter, lesser trochanter and calcar, and normal femur to the reference sacroiliac joint were obtained, as well as tip-to-stem, and stem-to-normal femur in unilateral arthroplasties. The ratios remained stable at 12 months and beyond, except for the tip and lesser trochanter. Tip-to-stem and tip-to-sacroiliac joint ratios decreased by 24% and 33%, respectively, between 12 and 49 mo. There was also a decrease in the relative uptakes at the lesser trochanter and calcar in the same time interval. Evidence is given that different designs of prostheses may not have the same normal temporal uptakes of radiophosphate.     

The effect of posterior knee capsulotomy on posterior tibial translation during posterior cruciate ligament tibial inlay reconstruction

PURPOSE: To measure the biomechanical effect of the surgical capsulotomy made during a posterior cruciate ligament reconstruction using the tibial inlay technique. HYPOTHESIS: The posterior capsule contributes to posterior tibial stability. STUDY DESIGN: Controlled laboratory experiment. METHODS: Six knee specimens were tested on a robotic testing system from 0 degrees to 120 degrees of flexion with the posterior cruciate ligament intact and resected and with a posterior capsulotomy identical to that performed during tibial inlay reconstruction (sham surgery). A longitudinal incision with medial and lateral soft tissue stripping sufficient to mount an inlay bone block and pass an Achilles tendon graft into the knee was made in the oblique popliteal ligament, muscle belly of the popliteus, and posterior capsule. The posterior tibial translation was measured under a posterior tibial load of 130 N at multiple flexion angles. RESULTS: Capsulotomy increased the posterior laxity compared with the posterior cruciate ligament-resected knee at every flexion angle. An additional 0.97 +/- 0.48 mm, 0.65 +/- 0.47 mm, 0.56 +/- 0.33 mm, 0.48 +/- 0.38 mm, and 0.94 +/- 0.60 mm of posterior laxity was recorded at 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion, respectively. These values were all statistically significant (P < .001). CONCLUSIONS: A posterior capsulotomy alone, without associated posteromedial or posterolateral disruption, produces additional posterior tibial translation in vitro compared with posterior cruciate ligament-deficient knee with intact capsule. CLINICAL RELEVANCE: Damage to the posterior capsule may contribute to the residual posterior laxity noted clinically after posterior cruciate ligament reconstruction.     

Evaluation of metastatic bone disease with pentavalent 99Tc(m)-dimercaptosuccinic acid: a comparison with whole-body scanning and 4/24 hour quantitation of vertebral lesions

The aim of this study was to establish the value of 99Tcm(V)-DMSA scintigraphy in the detection of metastatic bone lesions and compare the results to 99Tcm-MDP bone scintigraphy. Thirty-four patients presenting with metastatic bone disease (Group 1) and 12 controls with degenerative skeletal lesions (Group 2) were studied. Conventional bone scanning and 99Tcm(V)-DMSA whole-body scanning were performed on all patients. All scans were interpreted visually. Furthermore, lesion-to-normal bone ratios (L/N) in vertebral metastases on the 4 and 24 h bone scans were obtained in 58 lesions of cancer patients and in 23 benign (degenerative) vertebral lesions of the control group. 99Tcm-MDP L/N ratios at 24 h (3.08 +/- 0.32) were significantly higher than those at 4 h (2.48 +/- 0.24) in the malignant foci (P < 0.001). No significant difference was observed in benign lesions (P > 0.05). In 167 (164 metastatic, 3 traumatic) of 186 99Tcm-MDP positive lesions (90%) of Group 1, 99Tcm(V)-DMSA uptake was observed. The remaining 19 lesions (10%) were 99Tcm(V)-DMSA negative. Fourteen of these 19 sites were diagnosed as benign. The remaining five foci were malignant. In four lung cancer metastases showing no 99Tcm-MDP uptake, 99Tcm(V)-DMSA uptake was observed. There was no 99Tcm(V)-DMSA accumulation in any of the 99Tcm-MDP positive degenerative lesions of Group 2. All quantitatively evaluated (n = 42) vertebral metastatic foci and two compression fractures in Group 1 showed 99Tcm(V)-DMSA accumulation and an increased 99Tcm-MDP L/N ratio at 24 h. A total of 36 degenerative lesions (Groups 1 and 2) and one compression fracture (Group 1) showed neither 99Tcm(V)-DMSA uptake nor an increased 99Tcm-MDP L/N ratio at 24 h. Our results indicate that quantitative 4/24 h analysis of vertebral lesions on 99Tcm-MDP scans has a similar diagnostic value to 99Tcm(V)-DMSA imaging in the detection of bone metastases. However, the accumulation of 99Tcm(V)-DMSA in four lung cancer metastases showing no 99Tcm-MDP uptake is encouraging and justifies further research in patients with proven bone metastases and negative bone scans.     

The use of three-phase bone imaging in vascularized fibular and iliac bone grafts

Three-phase bone imaging was undertaken to monitor the viability of vascularized bone grafts after surgery. Eleven vascularized fibular grafts and six vascularized iliac grafts were reviewed. The study evaluated patients over multiple time intervals from 1 week to 6-8 weeks postoperatively. Follow-up ranged from 12 to 60 months. In most of the patients who achieved a successful clinical outcome, the study was positive; blood perfusion and blood pool radioactivity at sites of bone grafts were higher than those at recipient sites two weeks postoperatively and became equal to surrounding tissue thereafter. The grafted bone uptake of radiophosphate was constantly positive in these cases. Conversely, the study was negative in three cases of postoperative vascular complications. Serial three-phase bone imaging is a useful tool to monitor the viability and early complications of vascularized bone grafts after surgery.