Reestablishment of the Posterior Stability After the Posterior Cruciate Ligament-Released Cruciate Retaining Total Knee Arthroplasty

PURPOSE

The cruciate retaining (CR) design was developed to obtain knee stability with the natural posterior cruciate ligament (PCL) in total knee arthroplasty (TKA). However, the preservation of the PCL can limit knee exposure and increase the technical challenge during the procedure. Knee exposure is easily achieved under the released PCL, and we hypothesized that the PCL naturally repairs after release, thus re-establishing the posterior stability. Accordingly, the objective of this study was to evaluate the varying of the posterior stability after the PCL-released CR TKA over time.

METHODS

Eight consecutive patients received the CR TKA in which the entire PCL was subperiostealy released at its femoral insertion. Thereafter, the patients were examined with the Knee Society Score, the posterior drawer examination, and the knee ligament arthrometer postoperatively.

RESULTS

Once the PCL was released, the tibia was easily subluxated, and the knee was clearly exposed intraoperatively. However, the posterior stability significantly improved with time postoperatively. We also had confirmed the reestablishment of the PCL directly at revision TKAs, one case of which is shown.

CONCLUSION

The reestablishment of the posterior stability after the PCL-released CR TKA was demonstrated. This procedure to release the entire PCL subperiostealy is recommended as a means of facilitating CR TKA.

Combination of Accelerometer-Based Navigation and Force Sensor for Precise Bone Resection and Appropriate Soft Tissue Balancing in Total Knee Arthroplasty

Background: Precise bone resection and appropriate soft tissue balancing are considered indispensable in total knee arthroplasty (TKA). However, in most TKAs, only the experienced-based subjective physical “feel” of the surgeon, or either a computer-based navigation system or a soft tissue balancing system are applied to improve the results. In the present study, a combination of both an accelerometer-based navigation system and an electronic knee balancing force sensor were applied to attempt to obtain optimal outcomes.Materials and Methods: An accelerometer-based navigation system and an electronic knee balancing force sensor were applied in combination in 5 TKAs. Thereafter, the incidence of radiographical outliers of the lower-extremity mechanical axis and the alignments of femoral and tibial components, and the incidence of intraoperative lateral retinacular release were evaluated and compared against those of 5 TKAs performed with the force sensor alone as a control.Results: The posterior slope of the tibia was significantly improved in the TKAs performed with the combination of both devices (P=0.004). No lateral release was performed in any TKAs of either group.Conclusion: TKAs performed under the combination of an accelerometer-based navigation system and an electronic knee balancing force sensor can obtain greater the accuracy of bone resection and appropriate soft tissue balancing.

Pendulum Test: A Highly Accurate and Simple Physical Examination Maneuver to Identify Hip Pathology

Background: Patients with hip pathology often complain of various symptoms, e.g. pain or discomfort of low back, lower extremity, hip, groin, thigh, buttock or knee. Physicians may be distracted by these complaints, and misdiagnose and mistreat hip pathology. To avoid this, the pendulum test, which is performed with a patient seated on the examination table and hips and knees are flexed at 90 degrees, while the examiner passively swings the patient's lower extremity in and out as a pendulum, has been employed for all patients with the complaint of low back, hip and knee.Objective: The efficacy and the accuracy of the pendulum test were evaluated.Patients and methods: Consecutive 40 patients, who had complained pain or discomfort of low back, lower extremity, hip, groin, thigh, buttock and knee were examined by the pendulum test.Results: Eighteen patients were positive for the pendulum test, and all of them correlated to the hip pathology.Conclusions: The pendulum test was confirmed to be easily performed and reliable in detecting the hip pathology. Therefore, this test is highly recommended for the differentiation of patients with low back, hip and knee complaints.

Phialophora verrucosa as a cause of deep infection following total knee arthroplasty

Deep joint infection is one of the most feared complications following total joint replacement. Prompt diagnosis and treatment with 2-staged revision is currently the gold standard for treatment. We report a case of a chronic infection following total knee replacement caused by Phialophora verrucosa, a form of dematiaceous fungus. The patient was treated with an antibiotic spacer and a course of oral anti-fungal agents. To our knowledge, there have been no reported cases of P verrucosa as a cause of infection in hip or knee arthroplasty.

Evaluation of femoral strains with cementless proximal-fill femoral implants of varied stem length

BACKGROUND

The design intent of proximally-filling lateral flare femoral stems is to load the endosteal surface of the proximal femur both laterally and medially, to achieve normal bone strains. However, the long stem can contact the femoral cortex and may offload the proximal region to some extent. Therefore, in this study, we sought to determine if reducing the stem length, would result in physiologic strain patterns.

METHODS

Using the PhotoStress® method we analyzed 13 femurs intact and with three different stem length implants: stemless, ultra-short and short. The test rig loaded the femoral head by simulating the mid-stance single leg support phase of gait with the ilio-tibial band and the hip abductor forces. The strain distribution with each stem length implant was then compared to the intact strain distribution to determine which was most similar.

FINDINGS

As the stem length increased the femurs exhibited a typical pattern of reduced proximal strain and increased distal strain. However, there was some variation in this pattern indicating that the exact stem position and the location of its interaction with the endosteal surface of bone was not the same in each femur.

INTERPRETATION

The stemless design provided the best match compared to the native femur and therefore has the greatest potential to address the shortcomings of a stemmed femoral implant. However, the ultra-short implant also exhibited a strain distribution that closely emulated the intact femur, and may represent the best option as there are still several questions pertaining to stability and alignment of a stemless implant.

Promising mid-term results of total hip arthroplasties using an uncemented lateral-flare hip prosthesis: a clinical and radiographic study

The clinical results after total hip replacements using noncemented stems have shown considerable variability over the years; the design and characteristics of the implant seemed to play a role in explaining this fact. The purpose of this paper is to report the clinical, radiographic and densitometry results of total hip arthroplasties using a stem designed for noncemented implantation and to engage and load the femur proximally. Fifty-eight consecutive patients (62 hips) followed for an average of 4.3 years (range 36-70 months) were clinically and radiographically followed up at three weeks, three months, six months, one year, and yearly thereafter. The average pre-operative Harris hip score was 49 increasing to 98 at the latest follow-up. There were no cases of aseptic or septic loosening. The average subsidence at three years was 0.45 mm (SD +/- 0.36 mm). Radiographically all hips were classified as stable, and evident changes compatible with new bone apposition were observed in 64% of the cases. The extended proximal geometry of the device seems to favour initial and secondary stability as reflected by the low subsidence values over time. The maintenance of periprosthetic bone stock and the absence of stress shielding can be explained by the predominantly proximal loading pattern of the stem.

Relapsing oligoarticular septic arthritis during etanercept treatment of rheumatoid arthritis

Septic arthritis is a commonly reported complication of rheumatoid arthritis (RA). Tumor necrosis factor alpha (TNF-alpha) plays an important role in host defense against infection. Inhibition of its activity could therefore be anticipated to augment the risk of infection. Both opportunistic and bacterial infections have been described in patients with RA treated with anti-TNF-alpha therapy. We describe a patient who experienced 2 episodes of septic arthritis. Both occurred while the patient was on etanercept. Recurrence developed despite prolonged parenteral antibiotic. To our knowledge, this is the first report of relapsing oligoarticular methicillin-sensitive Staphylococcus aureus septic arthritis despite prolonged antibiotic treatment in a patient receiving etanercept therapy. Our case underscores the advisability of discontinuing TNF-alpha blockade in patients with septic arthritis during prolonged antimicrobial therapy.

Favorable midterm results of total hip arthroplasties with a lateral flare uncemented stem

Uncemented stems have been advocated for primary total hip arthroplasties in the young active population. We evaluated the clinical and radiographic results of total hip arthroplasties with a customized lateral flare cementless femoral stem in a prospective, consecutive series of 35 patients (40 hips) younger than 55 years at the time of surgery and who were followed up for an average of 9.2 years (range, 5.7-12.2 years). The study group comprised 20 men and 15 women with an average age of 45.2 years (range, 30-55 years). One patient had aseptic loosening of the stem and one patient had a deep infection. The mean preoperative Harris hip score was 47 and at the latest followup it was 97. The mean axial migration was 0.51 mm. Femoral osteolysis was found to be circumscribed to the proximal femur in Gruen Zones 1 (15%) and 7 (8%) in patients with accelerated polyethylene wear. Radiographic changes consistent with new bone apposition under the lateral flare of the stem in Zones 2, 6, and 7 were found in 73% of the cases. Our data suggest a custom lateral flare stem for primary arthroplasties in the younger patient population achieves excellent clinical results with a low rate of aseptic loosening.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series).

Three-dimensional dynamic hip contact area and pressure distribution during activities of daily living

Estimation of the hip joint contact area and pressure distribution during activities of daily living is important in predicting joint degeneration mechanism, prosthetic implant wear, providing biomechanical rationales for preoperative planning and postoperative rehabilitation. These biomechanical data were estimated utilizing a generic hip model, the Discrete Element Analysis technique, and the in vivo hip joint contact force data. The three-dimensional joint potential contact area was obtained from the anteroposterior radiograph of a subject and the actual joint contact area and pressure distribution in eight activities of daily living were calculated. During fast, normal, and slow walking, the peak pressure of moderate magnitude was located at the lateral roof of the acetabulum during mid-stance. In standing up and sitting down, and during knee bending, the peak pressures were located at the edge of the posterior horn and the magnitude of the peak pressure during sitting down was 2.8 times that of normal walking. The peak pressure was found at the lateral roof in climbing up stairs which was higher than that in going down stairs. These results can be used to rationalize rehabilitation protocols, functional restrictions after complex acetabular reconstructions, and prosthetic component wear and fatigue test set up. The same model and analysis can provide further insight to soft tissue loading and pathology such as labral injury. When the pressure distribution on the acetabulum is inverted onto the femoral head, prediction of subchondral bone collapse associated with avascular necrosis can be achieved with improved accuracy.

Evolution of the Koch model of the biomechanics of the hip: clinical perspective

Over the past several decades numerous researchers have revisited the model of the biomechanics of the hip first predicated by John Koch in 1917. The contributions of Blount (1956), Frankel (1960), Pauwels (1976), Toridis (1969), Rybicki (1972), Fetto (1994, 1995), Ling (1996), and Lu (1997, 1998) among others created a more complete picture. The present article briefly reviews the previous biomechanical concept and its clinical inconsistencies and offers a model that includes the dynamic and static input of the soft tissues. The action of the iliotibial band (ITB) and the vastus lateralis-gluteus medius complex (as static and dynamic tension bands lateral to the femur) counterbalance the varus bending torque of the loads acting on the hip, transforming the tensile stresses in the lateral femur (as hypothesized by Koch) into compressive stresses. The inclusion of the soft tissues, extending the previous model, widens our understanding of the forces acting on the hip. Thus, a variety of clinical observations can be better explained in a comprehensive theoretical framework.

Comprehensive deep venous thrombosis prevention strategy after total-knee arthroplasty

OBJECTIVE

Venous thromboembolism after total-knee arthroplasty represents a common early postoperative complication resulting in significant morbidity. Despite this, the optimal prophylactic regimen is controversial. The prevalence of venous thromboembolism has been cited as high as 35% in patients receiving pharmacologic prevention alone. We investigated the efficacy of a comprehensive prevention protocol encompassing the use of epidural anesthesia, aspirin, venous foot compression pumps, and early mobilization in a series of consecutive total-knee arthroplasties.

DESIGN

A series of 100 consecutive total-knee arthroplasty patients were enrolled into the prospective trial. All patients were allowed full weight bearing on the first postoperative day and ambulation as tolerated. Venous foot compression pumps and aspirin were used immediately after surgery in the totality of subjects. Seventy-five percent of the patients were transferred to an acute rehabilitation service during the first postoperative week. The presence of deep-vein thrombosis was subsequently determined with the routine use of venous duplex scans.

RESULTS

Three patients (3%) demonstrated evidence of distal deep-vein thrombosis. No patient had symptomatic pulmonary embolism.

CONCLUSION

The combination of epidural anesthesia, aspirin, immediate postoperative venous foot compression pumps, and early ambulation together seem to be a more effective approach to prevent the occurrence of thromboembolic events after knee replacements than pharmacologic prevention alone.

The effect of a lateral flare feature on implant stability

We reviewed the X-rays of 109 patients with 115 primary total hip replacements utilizing a lateral flare cementless stem to assess axial migration and stability. The average follow-up was 48.6 (24-104) months. The average subsidence at 2 years was 0.32 mm, remaining at a level below 1 mm for the duration of the follow-up. Even though there were ten reoperations involving either the change of a polyethylene liner and the acetabular component, or both, none of the patients required a femoral stem revision. It was concluded that the proximal geometry of the stem provides significant initial stability, which seems to be preserved throughout a long follow-up period.

Prevention of thromboembolic disease after non-cemented hip arthroplasty. A multimodal approach

Thromboembolism following total hip arthroplasty is a common complication that may result in significant morbidity and mortality. Despite this, optimal prophylactic regimen is controversial. We investigated the efficacy of a comprehensive approach encompassing the use of aspirin, intermittent compression devices ('foot pumps'), and early mobilization in a cohort of 200 consecutive patients after non-cemented total hip replacements. The surgical procedures were carried out under epidural anesthesia in most cases (91%). All patients were allowed full weight bearing and received ambulation training starting on the first post-operative day. Ankle-high pneumatic boots ('foot pumps') and aspirin (325 mg p.o./qd) were used immediately after surgery. The presence of deep vein thrombosis was determined with the routine use of venous duplex scans on post-operative day number 5 to 10 (mean 6.8). The duration of the follow-up was 3 months. No patients were lost to follow-up. Four distal DVT's (2%) were detected in three patients. None of the patients developed symptomatic pulmonary embolism during the follow-up period. There were no major wound complications. Venous thromboembolic disease after hip replacement surgery is largely associated with postoperative immobilization and venous stasis. It is the authors' opinion that a prevention strategy should include mechanical as well as pharmacological measures. The concomitant use of epidural anesthesia, "foot pumps", aspirin and early full weight bearing ambulation may be effective in further reducing the incidence of DVT after surgery.

Biostructural augmentation for the treatment of osteonecrosis: rationale, technique, and case example

Avascular necrosis of the hip is a common disease that usually affects a young and active patient population. As the disease progresses, the undermined structural integrity of the subchondral bone leads to articular collapse and subsequent osteoarthrosis. The ideal treatment is one that hinders or arrests the progression of the disease, averting articular collapse and joint replacement surgery. A surgical strategy is described that attempts to address the multiple factors involved in the progression of the disease. This is accomplished through a modified core decompression procedure combined with the insertion of two interference screws into the subchondral plate to provide structural support and the use of osteoinductive material (i.e., demineralized bone matrix) in an effort to accelerate the bone healing process.

Team physician #6. Surgical treatment of Achilles tendon rupture

The ideal treatment of Achilles tendon ruptures has always been controversial. Nonoperative treatment has been criticized for its high rerupture rate and surgical treatment has been criticized for its high complication rate. This paper describes a surgical method of repair that can be used for acute or late ruptures, and has been associated with a low complication and rerupture rate.

Low-intensity pulsed galvanic current and the healing of tenotomized rat achilles tendons: preliminary report using load-to-breaking measurements

The possible beneficial effects of low-intensity, pulsed galvanic currents on the healing of tenotomized Achilles tendons was investigated in three groups (20 animals each) of male Sprague-Dawley rats. Treatments via implanted electrodes were given once daily for 15 minutes over a two-week period. Although a portable high-voltage galvanic stimulator was used, stimulus intensity was only 75 microA at a frequency of 10/sec. Tendons were tested after two weeks for the load required to rebreak them at the original tenotomy site. The group treated with anodal current withstood significantly greater loads (p less than 0.001) than did either the group which healed normally (ie, without stimulation) or the group treated with cathodal current.