The Relationship between Pre- and Postoperative Range of Motion Utilizing Three Cruciate-Retaining Total Knee Prostheses

We prospectively examined the relationship between pre- and postoperative range of motion utilizing three cruciate retaining knees with various mechanical flexion potentials, i.e., two at about 130°–135° (one with posterior lip and the other without) and the third at about 140°–145°. All groups demonstrated mean flexion and range of motion of 116°–122° at one year. Combining data from the three cohorts, patients with the following preoperative flexion values achieved the indicated mean changes (increases) in flexion at one year: < 90° flexion (Δ 23.6°), 91°–105°flexion (Δ 19.3°), and > 105° flexion (Δ 1.8°)). Postoperative improvement was inversely related to preoperative flexion. The high flex knee yielded the best improvement in range of motion (9.7°increase) in the highest flex preoperative group compared to that of the other knees (?7.4° to 2.9°). Hence, a high flex knee design seems to be important in high preoperative range of motion patients obtaining an increase in the postoperative range of motion rather than possible regression.     

Polished Trays Reduce Backside Wear Independent of Post Location in Posterior-stabilized TKAs

Background

Backside damage of the polyethylene in TKA is a potential source of debris. The location of the tibial post in posterior-stabilized implants may influence micromotion, and thus affect backside damage, as may surface roughness.

Questions

We used implant retrieval analysis to (1) examine if there were differences in backside damage among three modern posterior-stabilized implants attributable to variable surface roughness; (2) determine if the location of damage on the tibial post affected the pattern of backside damage; and (3) determine if demographics influenced backside damage.

Methods

We identified 403 posterior-stabilized tibial retrieved inserts (147 NexGen^®, 152 Optetrak^®, 104 Genesis^® II). The damage on the surfaces of the tibial posts was previously graded. The backside of the inserts (divided into quadrants) were scored for evidence of damage. The total quadrant damage was compared for each implant group, the relationship between post face damage and location of damage on the backside was determined for each implant group, and total backside damage was compared among the three implant groups.

Results

No correlation was found between the location of damage on the post and location of damage on the backside of the implant for any of the three groups. The Genesis^® II polyethylene implants, which articulate with a highly polished tibial tray, showed a significantly lower total backside damage score (p < 0.01) when compared with the other two implant groups. The Genesis^® II and Optetrak^® showed significantly more damage in the posterior quadrants of the implants (p < 0.01) when compared with the anterior quadrants. A linear regression analysis revealed that lower tibial tray surface roughness was correlated with decreased damage.

Conclusions

An implant design with a highly polished tibial tray was associated with decreased backside damage. However, tibial post design and location did not influence the location of backside damage.

Clinical Relevance

Our study showed that a highly polished tibial tray was associated with decreased damage to the backside of polyethylene inserts independent of post design and location. These findings should be taken into consideration when new generations of implants are designed.     

Weight of Polyethylene Wear Particles is Similar in TKAs with Oxidized Zirconium and Cobalt-chrome Prostheses

Background  

The greater lubricity and resistance to scratching of oxidized zirconium femoral components are expected to result in less polyethylene wear than cobalt-chrome femoral components.     

Does Acetabular Retroversion Affect Range of Motion after Total Hip Arthroplasty?

Background  

Increasingly, acetabular retroversion is recognized in patients undergoing hip arthroplasty. Although prosthetic component positioning is not determined solely by native acetabular anatomy, acetabular retroversion presents a dilemma for component positioning if the surgeon implants the device in the anatomic position.     

Intraoperative Measurements of Joint Line Changes Using Computer Navigation Do Not Correlate With Postoperative Radiographic Measurements in Total Knee Arthroplasty

Background

The adverse effects of joint line (JL) changes on kinematics and outcomes of total knee arthroplasty (TKA) have been studied. Some authors have quantified JL changes using intraoperative data from computer navigation, despite no studies validating these measurements to date. We designed a prospective study to determine whether intraoperative measurements of JL changes using computer navigation correlate with measurements obtained on weight-bearing radiographs postoperatively.

Range of Motion Simulation of Hip Joint Movement During Salat Activity

Background

Impingement of an artificial hip joint because of limited range of motion (RoM) during human activity is one of the main sources of hip joint failure. The aim of this article is to simulate the RoMs of hip joints during salat, the practice of formal worship in Islam.

Osteomyelitis Risk in Patients With Transfemoral Amputations Treated With Osseointegration Prostheses

Background

Percutaneous anchoring of femoral amputation prostheses using osseointegrating titanium implants has been in use for more than 25 years. The method offers considerable advantages in daily life compared with conventional socket prostheses, however long-term success might be jeopardized by implant-associated infection, especially osteomyelitis, but the long-term risk of this complication is unknown.

Questions/Purposes

(1) To quantify the risk of osteomyelitis, (2) to characterize the clinical effect of osteomyelitis (including risk of implant extraction and impairments to function), and (3) to determine whether common patient factors (age, sex, body weight, diabetes, and implant component replacements) are associated with osteomyelitis in patients with transfemoral amputations treated with osseointegrated titanium implants.

Methods

We retrospectively analyzed our first 96 patients receiving femoral implants (102 implants; mean implant time, 95 months) treated at our center between 1990 and 2010 for osteomyelitis. Six patients were lost to followup. The reason for amputation was tumor, trauma, or ischemia in 97 limbs and infection in five. All patients were referred from other orthopaedic centers owing to difficulty with use or to be fitted with socket prostheses. If found ineligible for this implant procedure no other treatment was offered at our center. Osteomyelitis was diagnosed by medical chart review of clinical signs, tissue culture results, and plain radiographic findings. Proportion of daily prosthetic use when osteomyelitis was diagnosed was semiquantitatively graded as 1 to 3. Survivorship free from implant- associated osteomyelitis and extraction attributable to osteomyelitis respectively was calculated using the Kaplan-Meier estimator. Indication for extraction was infection not responsive to conservative treatment with or without minor débridement or loosening of implant.

Results

Implant-associated osteomyelitis was diagnosed in 16 patients corresponding to a 10-year cumulative risk of 20% (95% CI 0.12–0.33). Ten implants were extracted owing to osteomyelitis, with a 10-year cumulative risk of 9% (95% CI 0.04–0.20). Prosthetic use was temporarily impaired in four of the six patients with infection who did not undergo implant extraction. With the numbers available, we did not identify any association between age, BMI, or diabetes with osteomyelitis; however, this study was underpowered on this endpoint.

Conclusion

The increased risk of infection with time calls for numerous measures. First, patients should be made aware of the long-term risks, and the surgical team should have a heightened suspicion in patients with method-specific presentation of possible infection. Second, several research questions have been raised. Will the surgical procedure, rehabilitation, and general care standardization since the start of the program result in lower infection rates? Will improved diagnostics and early treatment resolve infection and prevent subsequent extraction? Although not supported in this study, it is important to know if most infections arise as continuous bacterial invasion from the skin and implant interface and if so, how this can be prevented?

Level of Evidence

Level IV, therapeutic study.

     

Postoperative Range of Motion Does Not Correlate with Patient Reported Outcome Scores in Asians after Total Knee Arthroplasty

Activities in Asian cultures require greater knee flexion. However, this study hypothesized that post-operative range of motion (ROM) does not correlate with patient reported outcome scores at 2 years. 292 TKAs were evaluated at a public hospital in Singapore from January 2006 to May 2009. The relationship between ROM and outcome scores was examined using a multiple linear regression model with Generalized Estimating Equation (GEE) allowing adjustment for confounders and repeated TKAs within a patient. Analysis did not yield statistically significant results when patients' post-op ROM was correlated with outcome scores at 2 years. Lack of post op ROM does not translate into poorer outcome scores and dissatisfaction. Doctors can now counsel patients who are concerned about a lack of ROM after TKA.     

Periacetabular Osteotomy Restores the Typically Excessive Range of Motion in Dysplastic Hips With a Spherical Head

BackgroundResidual acetabular dysplasia is seen in combination with femoral pathomorphologies including an aspherical femoral head and valgus neck-shaft angle with high antetorsion. It is unclear how these femoral pathomorphologies affect range of motion (ROM) and impingement zones after periacetabular osteotomy.Questions/purposes(1) Does periacetabular osteotomy (PAO) restore the typically excessive ROM in dysplastic hips compared with normal hips; (2) how do impingement locations differ in dysplastic hips before and after PAO compared with normal hips; (3) does a concomitant cam-type morphology adversely affect internal rotation; and (4) does a concomitant varus-derotation intertrochanteric osteotomy (IO) affect external rotation?MethodsBetween January 1999 and March 2002, we performed 200 PAOs for dysplasia; of those, 27 hips (14%) met prespecified study inclusion criteria, including availability of a pre- and postoperative CT scan that included the hip and the distal femur. In general, we obtained those scans to evaluate the pre- and postoperative acetabular and femoral morphology, the degree of acetabular reorientation, and healing of the osteotomies. Three-dimensional surface models based on CT scans of 27 hips before and after PAO and 19 normal hips were created. Normal hips were obtained from a population of CT-based computer-assisted THAs using the contralateral hip after exclusion of symptomatic hips or hips with abnormal radiographic anatomy. Using validated and computerized methods, we then determined ROM (flexion/extension, internal- [IR]/external rotation [ER], adduction/abduction) and two motion patterns including the anterior (IR in flexion) and posterior (ER in extension) impingement tests. The computed impingement locations were assigned to anatomical locations of the pelvis and the femur. ROM was calculated separately for hips with (n = 13) and without (n = 14) a cam-type morphology and PAOs with (n = 9) and without (n = 18) a concomitant IO. A post hoc power analysis based on the primary research question with an alpha of 0.05 and a beta error of 0.20 revealed a minimal detectable difference of 4.6° of flexion.ResultsAfter PAO, flexion, IR, and adduction/abduction did not differ from the nondysplastic control hips with the numbers available (p ranging from 0.061 to 0.867). Extension was decreased (19° ± 15°; range, −18° to 30° versus 28° ± 3°; range, 19°–30°; p = 0.017) and ER in 0° flexion was increased (25° ± 18°; range, −10° to 41° versus 38° ± 7°; range, 17°–41°; p = 0.002). Dysplastic hips had a higher prevalence of extraarticular impingement at the anteroinferior iliac spine compared with normal hips (48% [13 of 27 hips] versus 5% [one of 19 hips], p = 0.002). A PAO increased the prevalence of impingement for the femoral head from 30% (eight of 27 hips) preoperatively to 59% (16 of 27 hips) postoperatively (p = 0.027). IR in flexion was decreased in hips with a cam-type deformity compared with those with a spherical femoral head (p values from 0.002 to 0.047 for 95°–120° of flexion). A concomitant IO led to a normalization of ER in extension (eg, 37° ± 7° [range, 21°–41°] of ER in 0° of flexion in hips with concomitant IO compared with 38° ± 7° [range, 17°–41°] in nondysplastic control hips; p = 0.777).ConclusionsUsing computer simulation of hip ROM, we could show that the PAO has the potential to restore the typically excessive ROM in dysplastic hips. However, a PAO can increase the prevalence of secondary intraarticular impingement of the aspherical femoral head and extraarticular impingement of the anteroinferior iliac spines in flexion and internal rotation. A cam-type morphology can result in anterior impingement with restriction of IR. Additionally, a valgus hip with high antetorsion can result in posterior impingement with decreased ER in extension, which can be normalized with a varus derotation IO of the femur. However, indication of an additional IO needs to be weighed against its inherent morbidity and possible complications. The results are based on a limited number of hips with a pre- and postoperative CT scan after PAO. Future prospective studies are needed to verify the current results based on computer simulation and to test their clinical importance.

Level of Evidence

Level III, therapeutic study.     

The Effect of Geometric Variations in Posterior-stabilized Knee Designs on Motion Characteristics Measured in a Knee Loading Machine

Background

In different posterior-stabilized (PS) total knees, there are considerable variations in condylar surface radii and cam-post geometry. To what extent these variations affect kinematics is not known. Furthermore, there are no clearly defined ideal kinematics for a total knee.

Questions/purposes

The purposes of this study were to determine (1) what the kinematic differences are caused by geometrical variations between PS total knee designs in use today; and (2) what design characteristics will produce kinematics that closely resemble that of the normal anatomic knee.

Methods

Four current PS designs with different geometries and one experimental asymmetric PS design, with a relatively conforming medial side, were tested in a purpose-built machine. The machine applied combinations of compressive, shear, and torque forces at a sequence of flexion angles to represent a range of everyday activities, consistent with the ASTM standard test for measuring constraint. The femorotibial contact points, the neutral path of motion, and the AP and internal-external laxities were used as the kinematic indicators.

Results

The PS designs showed major differences in motion characteristics among themselves and with motion data from anatomic knees determined in a previous study. Abnormalities in the current designs included symmetric mediolateral motion, susceptibility to excessive AP medial laxity, and reduced laxity in high flexion. The asymmetric-guided motion design alleviated some but not all of the abnormalities.

Conclusions

Current PS designs showed kinematic abnormalities to a greater or lesser extent. An asymmetric design may provide a path to achieving a closer match to anatomic kinematics.

Clinical Relevance

One criterion for the evaluation of PS total knees is how closely the kinematics of the prosthesis resemble that of the anatomic knee, because this is likely to affect the quality of function.     

同种异体关节移植的手术配合

对13例患者行同种异体关节移植手术.结果 均顺利完成手术,未发生术中、术后并发症.提出重视患者的心理护理,充分的术前准备,正确熟练的手术配合及术中护理是顺利手术的重要环节.     

Polyethylene Damage Increases With Varus Implant Alignment in Posterior-stabilized and Constrained Condylar Knee Arthroplasty

Background

Implant malalignment in primary TKA has been reported to increase stresses placed on the bearing surfaces of implant components. We used a longitudinally maintained registry coupled with an implant retrieval program to consider whether preoperative, postoperative, or prerevision malalignment was associated with increased risk of revision surgery after TKA.

Questions/purposes

(1) What is the relative polyethylene damage on medial and lateral compartments of the tibial plateaus from revised TKAs? (2) Does coronal TKA alignment affect implant performance, such that TKAs aligned in varus are predisposed to experience increased polyethylene damage? (3) Does TKA alignment differ between postoperative and prerevision radiographs, and if so, what does this difference suggest about the mechanical contact load placed on a knee with a TKA?

Methods

Between 2007 and 2012, we performed 18,065 primary TKAs at our institution. By March 2016, 178 of those TKAs (1%) were revised at our center at least 2 years after primary surgery at our institution. Eighteen of those TKAs were excluded from this analysis because the tibial insert was not explanted during revision surgery, and four more were excluded because the inserts were lost or returned to the patient before the study was initiated, leaving 156 retrieved polyethylene tibial inserts (in 153 patients) revised at greater than 2 years after the primary TKA for this retrospective study. Patients who underwent revision surgery elsewhere were not considered here, since this study depended on having retrieved components. Polyethylene damage modes of burnishing, pitting, scratching, delamination, surface deformation, abrasion, and third-body debris were subjectively graded on a scale of 0 to 3 to reflect the extent and severity of each damage mode. On preoperative, postoperative, and prerevision radiographs, overall alignment, femoral alignment, and tibial alignment in the coronal plane were measured according to the protocol recommended by the Knee Society.

Results

Knees with more overall varus alignment after TKA had increased total damage on the retrieved tibial inserts (Spearman’s rank correlation coefficients of −0.3 [95% CI, −0.4 to −0.1; p = 0.001]). We also found revised TKAs tended to drift back into greater varus before revision surgery, with a mean (SD) of 3.6° ± 4.0° valgus for postoperative alignment compared with 1.7° ± 6.4° prerevision (p = 0.04).

Conclusions

Despite surgical efforts to achieve neutral mechanical alignment, remaining varus alignment places an increased contact load on the polyethylene articular surfaces. The drift toward further varus alignment postoperatively is consistent with the knee adduction moment remaining high after surgery.

Clinical Relevance

While we found a predisposition toward recurrence of the preoperative varus deformity, we did not find increased medial as opposed to lateral polyethylene damage, which may be explained by the curve-on-curve toroidal design of the articulating surfaces of the TKA implants in this study.

     

Mild Preoperative Systolic Dysfunction Associated With the Use of Intraoperative Vasopressors but Not Postoperative Survival in Liver Transplantation

BackgroundMild left ventricular systolic dysfunction (LVSD) is common in patients waiting for liver transplantation (LT), but its impact on intraoperative management and survival is poorly understood. In this study, we investigated if mild pretransplant LVSD was associated with the use of intraoperative vasopressors and 1-year survival after LT.MethodsAfter institutional review board approval, preoperative echocardiographic and perioperative data of adult patients undergoing LT between January 2006 and October 2013 were reviewed. Patients with or without mild LVSD were compared using the t test or Pearson’s χ² test. Independent risk factors were identified using multivariate logistic regression.ResultsOf 1055 adult patients, 11 (1.0%) had mild LVSD. Preoperative variables were similar between the 2 groups except for age and preoperative vasopressor use. Intraoperatively, a greater portion of patients with LVSD required vasopressors following anesthesia induction (71.4% vs 20.5%), immediately after reperfusion (100% vs 62.1%), and at the end of the transplant (100% vs 38.5%) compared with patients without LVSD (all P < .05). Multivariate logistic analysis showed that LVSD was an independent risk factor (odds ratio, 4.7; 95% CI 1.0–21.3; P = .043) for increased requirement of intraoperative vasopressor along with other risk factors, including encephalopathy, preoperative pressors, male sex, high model for end-stage liver disease score, and long cold ischemia time. Patients with mild LVSD had similar 1-year survival rates compared with non-LVSD patients.ConclusionsPatients with mild preoperative LVSD, with proper intraoperative management, could undergo LT surgery and had comparable 1-year survival. Patients with mild preoperative LVSD alone should not be excluded from LT.     

Isocentric 3-Dimensional C-Arm Imaging of Component Alignments in Total Knee Arthroplasty With Potential Intraoperative and Postoperative Applications

An intraoperative imaging tool for total knee arthroplasty could help avoid poor clinical outcomes related to malalignment. We investigated the feasibility of using isocentric (ISO-C) fluoroscopic imaging for this purpose. Three-dimensional ISO-C and computed tomographic (CT) images were acquired from 6 cadaveric specimens implanted with standard knee arthroplasty components and analyzed to determine rotational alignments. In comparison with standard CT measures, the ISO-C–based measures had overall accuracies (determined as root mean square error) of 0.8° and 1.3° and corresponding SDs of 1.3° and 1.4° for the femoral and tibial components, respectively. With ISO-C imaging, it is possible to measure rotational alignment in knee arthroplasty with accuracy and repeatability comparable with CT. Isocentric imaging has strong potential as an intraoperative tool to accurately align arthroplasty components.     

Quantification of Pancreatic Stiffness on Intraoperative Ultrasound Elastography and Evaluation of its Relationship With Postoperative Pancreatic Fistula

“Soft pancreas” has often been reported as a predictive factor for postoperative pancreatic fistula (POPF) after pancreatectomy. However, pancreatic stiffness is judged subjectively by surgeons, without objective criteria. In the present study, pancreatic stiffness was quantified using intraoperative ultrasound elastography, and its relevance to POPF and histopathology was investigated. Forty-one patients (pancreatoduodenectomy, 30; distal pancreatectomy, 11) who underwent intraoperative elastography during pancreatectomy were included. The elastic ratio was determined at the pancreatic resection site (just above the portal vein) and at the remnant pancreas (head or tail). Correlations between the incidence of POPF and patient characteristics, operative variables, and the elastic ratio were examined. In addition, the relationship between the elastic ratio and the percentage of the exocrine gland at the resection stump was investigated. For pancreatoduodenectomy patients, main pancreatic duct diameter < 3.2 mm and elastic ratio < 2.09 were significant risk factors for POPF. In addition, the elastic ratio, but not main pancreatic duct diameter, was significantly associated with the percentage of exocrine gland area at the pancreatic resection stump. Pancreatic stiffness can be quantified using intraoperative elastography. Elastography can be used to diagnose “soft pancreas” and may thus be useful in predicting the occurrence of POPF.Key words: Elastography, Exocrine gland, Pancreatectomy, Pancreatic stiffness, Postoperative pancreatic fistulaDespite current advances in surgical techniques, pancreatectomy is a very difficult procedure associated with the risk of multiple postoperative complications. The morbidity and mortality are reported to be 20–50% and 1–5%, respectively.¹ In particular, a postoperative pancreatic fistula (POPF) can sometimes lead to life-threatening complications, such as hemoperitoneum and sepsis. The worldwide incidence of POPF is reported to be 5–50%. Several predictive factors for POPF have been reported to date, and, of these, “soft pancreas” has often been mentioned.^2–4 However, in all of these reports, evaluation of pancreatic stiffness has depended on subjective judgment by the surgeon, without objective parameters as criteria.Elastography has recently been developed to enable real-time visualization of the relative stiffness of tissue elasticity, and its usefulness in various clinical disciplines for tumor diagnosis and differential diagnosis has been described.⁵ In gastroenterology, evaluation of liver fibrosis and diagnosis of pancreatic tumors and chronic pancreatitis using endoscopic ultrasound (EUS) have been reported,^6,7 but the use of elastography in surgery has not been reported. An objective assessment of pancreatic stiffness as a predictive risk factor for POPF can help in choosing the intraoperative surgical technique and in planning the postoperative management strategy. Therefore, in the present study, pancreatic stiffness was quantified using intraoperative ultrasound elastography, and its relevance to POPF and histopathology was investigated.