Lawrence S. Crossett

Malrotation causing patellofemoral complications after total knee arthroplasty.

Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements without patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and tibial components. The group with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of combined internal rotation (1°-4°) correlated with lateral tracking and patellar tilting. Moderate combined internal rotation (3°-8°) correlated with patellar subluxation. Large amounts of combined internal rotational (7°-17°) correlated with early patellar dislocation or late patellar prosthesis failure. The control group was in combined external rotation (10°-0°). The direct correlation of combined (femoral and tibial) internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axial alignment. The epicondylar axis and tibial tubercle are reproducible landmarks which are visible on computed tomography scans and can be used intraoperatively. Using this computed tomography study can determine whether rotational malalignment is present and thus, whether revision of one or both components may be indicated.

Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis

The posterior condylar surfaces of the femur are routinely used as the reference for the rotational orientation of the femoral component during most primary total knee arthroplasties. The purpose of this investigation was to identify a clearly discernible, reproducible secondary anatomic axis useful for determining the rotational orientation of the femoral component when the posterior condylar surfaces cannot be used. Seventy-five embalmed anatomic specimen femurs were studied. A surgical epicondylar axis was defined as the line connecting the lateral epicondylar prominence and the medial sulcus of the medial epicondyle. The posterior condylar angle was measured as the angle between the posterior condylar surfaces and the surgical epicondylar axis. Measurement of the posterior condylar angle referenced from the surgical epicondylar axis yielded a mean posterior condylar angle of 3.5 degrees (+/- 1.2 degrees) of internal rotation for males and a mean posterior condylar angle of 0.3 degree (+/- 1.2 degrees) of internal rotation for females. Thus, rotational alignment of the femoral component can be accurately estimated using the posterior condylar angle. The posterior condylar angle, referenced from the surgical epicondylar axis, provides a visual rotational alignment check during primary arthroplasty and may improve alignment of the femoral component at revision.

Reconstruction of a ruptured patellar tendon with achilles tendon allograft following total knee arthroplasty.

Background: Rupture of the patellar tendon after total knee arthroplasty is a rare and debilitating complication. Proper surgical management of this condition remains controversial. The purpose of this study was to review the results of reconstruction of a ruptured patellar tendon with an Achilles tendon allograft following total knee arthroplasty.Methods: We reviewed our experience with the use of a fresh-frozen Achilles tendon allograft with an attached calcaneal bone graft to restore extensor function in nine patients with patellar tendon rupture following total knee arthroplasty (five primary and four revision). All patients were examined clinically and radiographically at an average of twenty-eight months.Results: The average knee and functional scores improved from 26 and 14 points, respectively, before the surgery to 81 and 53 points after the surgery. The average extensor lag decreased from 44° preoperatively to 3° postoperatively, and the average range of motion of the knee increased from 88° to 107°. Two grafts failed in the early postoperative period. Both were repaired successfully. Radiographs showed an average proximal patellar migration of 17.8 mm, which did not appear to affect extensor function.Conclusions: This short-term follow-up study showed that once an Achilles allograft has healed, it can serve as a reliable reconstruction of a ruptured patellar tendon following total knee arthroplasty. This technique may be particularly suited for patients in whom the extensor mechanism was compromised by multiple prior operations. Continued follow-up is necessary to determine the long-term durability of these results.

Postoperative infection following orthopaedic surgery in human immunodeficiency virus-infected hemophiliacs with CD4 counts ≤ 200/mm3

Human immunodeficiency virus-infected hemophiliacs are at risk for bacterial and opportunistic infections with worsening immunosuppression. Thus, the risk of postoperative infection following orthopaedic surgery is of considerable concern. A survey of United States hemophilia treatment centers was conducted to determine the incidence of postoperative infection in human immunodeficiency virus-positive hemophiliacs with CD4 counts of 200 mm3 or less undergoing orthopaedic surgery. A total of 115 centers from 37 states reported that postoperative infection occurred in 10 (15.1%) of 66 patients undergoing 74 orthopaedic procedures, between several weeks and 5 months following surgery. In five (50%), pre-operative infection preceded postoperative joint infection. Staphylococcus was the most common organism isolated in a prosthetic joint infection, in 6 of 10 (60.0%), and the knee was the most commonly affected joint, in 9 of 10 (90.0%). Joint arthroplasty appeared to have 10 times the risk of nonarthroplasty procedures for postoperative infection (9 of 34 [26.5%] and 1 of 40 [2.5%], respectively, P < .01). Two subjects developed chronic osteomyelitis. The rate of postoperative infection in human immunodeficiency virus-positive hemophiliacs with CD4 counts of 200/mm3 or less appears to be high, when compared with the general population. Early, vigorous treatment should be instituted for suspected infection, antibiotic prophylaxis considered for invasive procedures, and surgical intervention individualized based on the balance of risks and benefits.

Predicting discharge outcome after elective hip and knee arthroplasty

The objective of this prospective study was to determine if differences exist between individuals who require an inpatient rehabilitation program after elective hip and knee arthroplasty from those patients who can be discharged directly home. Multiple variables consisting of baseline demographics, social status, insurance status, medical history, pain level, quantitative strength, range of motion, and functional ability were examined. The primary outcome measure was the discharge destination from the orthopedic service and consisted of either a discharge to home or a discharge to an inpatient rehabilitation unit. Of the 162 patients followed, 65 (40%) were discharged to an inpatient rehabilitation unit, whereas 97 were discharged to home. The patients discharged to inpatient rehabilitation tended to live alone, were significantly older (mean difference = 6.3 yr), and had increased comorbid conditions (P < 0.001 for all variables). Patients discharged to a rehabilitation unit reported significantly greater pain levels than those discharged to home (P < 0.001). The attainment of a supervision level of function demonstrated greater differences between groups than the attainment of independent function for all functional measures. A logistic regression model was developed that predicted 76% of the discharges to rehabilitation by the third physical therapy session postsurgery. In conclusion, predictive markers do exist that differentiate individuals who require further inpatient therapy services after joint replacement surgery.

Preoperative Screening/Decolonization for Staphylococcus aureus to Prevent Orthopedic Surgical Site Infection Prospective Cohort Study With 2-Year Follow-Up

We quantified surgical site infections (SSIs) after preoperative screening/selective decolonization before elective total joint arthroplasty (TJA) with 2-year follow-up and 2 controls. Concurrent controls (n = 2284) were patients of surgeons not participating in screening/decolonization. Preintervention controls (n = 741) were patients of participating surgeons who underwent TJA the previous year. Staphylococcus aureus nasal carriers (321/1285 [25%]) used intranasal mupirocin and chlorhexidine baths as outpatients. Staphylococcal SSIs occurred in no intervention patients (0/321) and 19 concurrent controls. If all SSIs occurred in carriers and 25% of controls were carriers, staphylococcal SSI rate would have been 3.3% in controls (19/571; P = .001). Overall SSI rate decreased from 2.7% (20/741) in preintervention controls to 1.2% (17/1440) in intervention patients (P = .009). Preoperative screening/selective decolonization was associated with fewer SSIs after elective TJA.

A biochemical, histologic, and immunohistologic analysis of membranes obtained from failed cemented and cementless total knee arthroplasty.

Biochemical, histologic, and immunohistochemical analyses were performed on 34 interface membranes obtained from 33 patients during revision total knee arthroplasty. The membranes had surrounded components of cementless (n=11) and cemented (n=23) knee prostheses that were aseptically loose. None of these implant failures was caused by catastrophic polyethylene erosion leading to metal-to-metal contact. The histologic findings were similar in the membranes from cemented and cementless knee components: small polyethylene debris within macrophages and large birefringent polyethylene debris within foreign-body giant cells. Metallic debris was seen in membranes from both groups, but cemented membranes had more polymethylmethacrylate particles and more hyalinization

Long-Term Clinical Outcomes and Survivorship After Total Knee Arthroplasty Using a Rotating Platform Knee Prosthesis

A systematic search identified 29 papers reporting survivorship and clinical and function Knee Society Scores (KSS) of 6437 total knee replacements using the Low Contact Stress (LCS) Rotating Platform (RP) mobile bearing knee. Low Contact Stress RP survivorship and KSS outcomes were compared with non-LCS knees in the Swedish knee registry at comparable time periods and in 2 independent systematic reviews of knee arthroplasty outcomes. There is a substantial body of mainly observational evidence supporting the LCS RP knee. Knee Society Score outcomes were comparable for LCS RP and non-LCS RP knees at up to 15 years of follow-up, with mean clinical and function scores ranging from 72 to 96 and 58 to 90, respectively. Survivorship of LCS RP knees up to 14 years was higher than that for all knees in the Swedish Knee Registry.

Recovery of articular cartilage metabolism following thermal stress is facilitated by IGF-1 and JNK inhibitor.

Background The safety of intra-articular use of thermal probes is related to whether chondrocytes can tolerate exposure to high temperatures and whether cytoprotective agents may improve chondrocyte survival after thermal injury. Purpose This study was conducted to characterize the metabolic responses of articular cartilage after short-term exposure to temperatures between 50 ° C and 60 ° C with and without addition of insulin-like growth factor 1 (IGF-1) and c-Jun N-terminal kinase (JNK) inhibitor. Methods Human articular cartilage from osteoarthritic knees was subjected to defined thermal stress. Results Although significant reduction of proteoglycan synthesis was observed after 5 seconds of exposure to 55 ° C and 60 ° C and after 10- to 30-second exposures to 53 ° C, recovery of metabolic activity levels was observed after 7 days. Conclusion Addition of IGF-1 and JNK inhibitor Sp600125 enabled the cartilage to maintain significantly higher levels of proteoglycan synthesis immediately after thermal stress. IGF-1 also enhanced recovery of metabolic activity after 7 days. Clinical Significance Results from this study indicate that there may be time and temperature parameters within which thermal chondroplasty can be safely performed. The data additionally suggest that inadvertent chondrocyte injury may be minimized through potential addition of substances like IGF-1 or JNK inhibitor.

Primary versus secondary distal femoral arthroplasty for treatment of total knee arthroplasty periprosthetic femur fractures.

Current methods of fixing periprosthetic fractures after total knee arthroplasty (TKA) are variable, and include open reduction and internal fixation (ORIF) via plating, retrograde nailing, or revision using standard revision TKA components or a distal femoral arthroplasty (DFA). The purpose of this study is to compare patients who failed plating techniques requiring subsequent revision to DFA to patients who underwent primary DFA. Of the 13 patients (9.2%) who failed primary ORIF, causes included nonunion (53.8%), infection (30.8%), loosening (7.7%), and refracture (7.7%). There were significantly more surgical procedures for ORIF revision to DFA compared to primary DFA. Complications for patients who underwent primary reconstruction with DFAs included extensor mechanism disruption (8.3%), infection (5.6%), and dislocation (2.8%). Primary reconstruction via ORIF is beneficial for preserving bone stock, but primary DFA may be preferred in osteopenic patients, or those at high risk for nonunion.