Mark W. Pagnano

Effect of Postoperative Mechanical Axis Alignment on the Fifteen-Year Survival of Modern, Cemented Total Knee Replacements

BACKGROUND One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers. METHODS Clinical and radiographic data were reviewed retrospectively to determine the fifteen-year Kaplan-Meier survival rate following 398 primary total knee arthroplasties performed with cement in 280 patients from 1985 to 1990. Preoperatively, most knees were in varus mechanical alignment (mean and standard deviation, 6° ± 8.8° of varus [range, 30° of varus to 22° of valgus]), whereas postoperatively most knees were corrected to neutral (mean and standard deviation, 0° ± 2.8° [range, 8° of varus to 9° of valgus]). Postoperatively, we defined a mechanically aligned group of 292 knees (with a mechanical axis of 0° ± 3°) and an outlier group of 106 knees (with a mechanical axis of beyond 0° ± 3°). RESULTS At the time of the latest follow-up, forty-five (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with fourteen (13%) of the 106 implants in the outlier group (p = 0.88); twenty-seven (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with eight (7.5%) of the 106 implants in the outlier group (p = 0.88); and seventeen (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with four (3.8%) of the 106 implants in the outlier group (p = 0.49). CONCLUSIONS A postoperative mechanical axis of 0° ± 3° did not improve the fifteen-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.

The Effect of Superior Placement of the Acetabular Component on the Rate of Loosening after Total Hip Arthroplasty. Long-Term Results in Patients Who Have Crowe Type-II Congenital Dysplasia of the Hip*

A method for measurement of the true acetabular region and the approximate femoral head center as well as a classification consisting of four zones for assessment of the acetabular position of the acetabular cup were used to analyze the results of primary total hip arthroplasty with cement in 117 patients (145 hips). All patients had Crowe type-II congenital dysplasia of the hip. The mean age at the time of the arthroplasty was fifty-one years (range, fifteen to seventy-six years), and the mean duration of follow-up was fourteen years (range, two to twenty-two years). The initial position of the acetabular cup outside of the true acetabular region and outside of zone 1 (inferior and medial) was associated with an increase in the rates of loosening (p < 0.05) and revision (p < 0.04) of the femoral components. Cups that initially were more than fifteen millimeters superior to the approximate femoral head center, without lateral displacement, were associated with an increased rate of loosening (p < 0.001) and of revision (p < 0.04) of the femoral components as well as with an increased rate of loosening (p < 0.002) and of revision (p < 0.01) of the acetabular components. These findings suggest that superior positioning of the acetabular component, even without lateral displacement, leads to increased rates of loosening of the femoral and acetabular components. An attempt should be made to position the acetabular component in or near the true acetabular region.

Flexion instability after primary posterior cruciate retaining total knee arthroplasty

Between 1990 and 1995, 25 painful primary posterior cruciate ligament retaining total knee arthroplasties were revised for flexion instability. These patients shared typical clinical presentations that included a sense of instability without frank giving way, recurrent knee joint effusion, soft tissue tenderness involving the pes anserine tendons and the retinacular tissue, posterior instability of 2+ or 3+ with a posterior drawer or a posterior sag sign at 90° flexion, and above average motion of their total knee arthroplasty. The primary total knee arthroplasty was performed for osteoarthritis in 23 patients and rheumatoid arthritis in two patients. There were 13 male and 12 female patients and their mean age was 65 years (range, 35-77 years). Before the revision operation, Knee Society knee scores averaged 45 points (range, 17-68 points) and function scores averaged 42 points (range, 0-60 points). Twenty-two of the knee replacements were revised to posterior stabilized implants and three underwent tibial polyethylene liner exchange only. Nineteen of the 22 knee replacements revised to a posterior stabilized implant were improved markedly after the revision surgery. Only one of three knee replacements that underwent tibial polyethylene exchange was improved. After the revision for flexion instability, Knee Society knee scores averaged 90 points (range, 82-99 points) and function scores averaged 75 points (range, 45-100 points) for the 20 knees with a successful outcome. This study suggests that flexion instability can be a cause of persistent pain and functional impairment after posterior cruciate ligament retaining total knee arthroplasty. A revision operation that focuses on balancing the flexion and extension spaces, in conjunction with a posterior stabilized knee implant, seems to be a reliable treatment for symptomatic flexion instability after posterior cruciate retaining total knee arthroplasty.

Muscle damage during MIS total hip arthroplasty : Smith-Petersen versus posterior approach

Decreased muscle damage is a reported benefit of minimally invasive surgical (MIS) approaches in total hip arthroplasty (THA). We compared the extent and location of muscle damage during THA using the MIS anterior Smith-Peterson and MIS posterior surgical approaches. THA was performed in six human cadavers (12 hips). One hip was assigned to the Smith-Peterson approach and the contralateral hip to the posterior approach. Muscle damage was graded with a technique of visual inspection to calculate a proportion of surface area damage. Less damage occurred in the gluteus minimus muscles and minimus tendon with the Smith-Peterson approach. A mean of 8% of the minimus muscle was damaged via the Smith-Peterson approach, compared to 18% via the posterior approach. The tensor fascia latae muscle was damaged (mean of 31%), as well as direct head of the rectus femoris (mean 12%) during the Smith-Peterson approach. The piriformis or conjoined tendon was transected in 50% of the anterior approaches to mobilize the femur. The posterior approach involved intentional detachment of the piriformis and conjoined tendon and measurable damage to the abductor muscles and gluteus minimus tendon in each specimen. Clinical outcome studies and gait analysis are necessary to ascertain the functional implications of these findings.

The Frank Stinchfield Award: muscle damage after total hip arthroplasty done with the two-incision and mini-posterior techniques.

Some surgeons have suggested that a minimally invasive two-incision approach allows total hip arthroplasty to be done without cutting or damaging any muscle or tendon. To our knowledge that claim has not been supported by any published clinical or basic science data. Our purpose in doing this study was to quantify the extent and location of damage to the abductor and external rotator muscles and tendons after two-incision and mini-posterior total hip arthroplasty. Ten cadavers (20 hips) were studied. In each cadaver one hip randomly was assigned to the two-incision group and the contralateral hip was assigned to the mini-posterior group. After inserting the total hip arthroplasty components the muscle damage was assessed using a technique described previously. Damage to the muscle of the gluteus medius and gluteus minimus was substantially greater with the two-incision technique than with the mini-posterior technique. Every two-incision total hip replacement caused measurable damage to the abductors, the external rotators, or both. Every mini-posterior hip replacement caused the external rotators to detach during the exposure and had additional measurable damage to the abductor muscles and tendon. We do not support the contention that a two-incision total hip arthroplasty is done without cutting muscle or tendon. None of the two-incision hip replacements were done without cutting, reaming, or damaging the gluteus medius or gluteus minimus muscle or external rotators.

Analgesia for Total Hip and Knee Arthroplasty: A Multimodal Pathway Featuring Peripheral Nerve Block

Patients undergoing total hip and knee arthroplasty experience substantial and sustained postoperative pain. Inadequate analgesia may impede physical therapy and rehabilitative efforts and delay hospital dismissal. Traditionally, postoperative analgesia after total joint replacement was provided by either intravenous patient-controlled analgesia or epidural analgesia. Each, however, had disadvantages as well as advantages. Peripheral nerve blockade of the lumbosacral plexus has emerged as an alternative analgesic approach. In several studies, unilateral peripheral block provided a quality of analgesia and functional outcomes similar to those of continuous epidural analgesia and superior to those of systemic analgesia, but with fewer side effects because of their opioid-sparing properties. Peripheral nerve block techniques may be the optimal analgesic method following total joint arthroplasty.

Two-incision THA had modest outcomes and some substantial complications.

Proponents of two-incision total hip arthroplasty suggest the technique is minimally invasive and promotes rapid rehabilitation with a low prevalence of complications. We applied the two-incision total hip arthroplasty technique to a consecutive group of unselected patients with primary degenerative arthritis to determine the technical difficulty of the operation as measured by the operative time compared with a standard posterior approach, the safety of the operation as measured by the prevalence of complications compared with a standard posterior approach, and the early functional outcome measured by the time to return to activities of daily living as compared with a previous study of the two-incision technique in selected younger patients. The 80 patients included 45 women and 35 men with a mean age of 70.5 years. The patients treated with a two-incision method had longer operative times and substantially more complications than did the patients treated with a standard posterior approach. The early functional outcomes in this group of unselected patients were modest when compared with the previous results in selected younger patients. Patient and surgeon enthusiasm for the potential benefits of the two-incision total hip arthroplasty should be tempered by the modest early outcomes and the substantial prevalence of complications found in this group of typical patients having total hip arthroplasty. Level of Evidence: Prognostic study, Level III (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Low Risk of Thromboembolic Complications With Tranexamic Acid After Primary Total Hip and Knee Arthroplasty

BackgroundThe use of antifibrinolytic medications in hip and knee arthroplasty reduces intraoperative blood loss and decreases transfusion rates postoperatively. Tranexamic acid (TXA) specifically has not been associated with increased thromboembolic (TE) complications, but concerns remain about the risk of symptomatic TE events, particularly when less aggressive chemical prophylaxis methods such as aspirin alone are chosen.Questions/purposesWe determined whether the rate of symptomatic TE events differed among patients given intraoperative TXA when three different postoperative prophylactic regimens were used after primary THA and TKA.MethodsWe retrospectively reviewed 2046 patients who underwent primary THA or TKA and received TXA from 2007 to 2009. The three chemical regimens included aspirin alone, warfarin (target international normalized ratio, 1.8–2.2), and dalteparin. Primary outcome measures were venous TE events, including symptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE), and arterioocclusive events, including myocardial infarction and cerebrovascular accident. Patients judged to be at high risk for TE due to recent cardiac stent placement or strong personal/family history of TE disease were excluded.ResultsFor aspirin, warfarin, and dalteparin, the rates of symptomatic DVT (0.35%, 0.15%, and 0.52%, respectively) and nonfatal PE were similar (0.17%, 0.43%, and 0.26%, respectively). There were no fatal PE. Among the three groups, we found no difference in the rates of symptomatic DVT or PE with or without stratification by ASA score.ConclusionsA low complication rate was seen when using TXA as a blood conservation modality during primary THA and TKA with less aggressive thromboprophylactic regimens such as aspirin alone and dose-adjusted warfarin.Level of EvidenceLevel III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

A Comprehensive Anesthesia Protocol That Emphasizes Peripheral Nerve Blockade for Total Knee and Total Hip Arthroplasty

R ecently, advances in radiographic imaging and surgical instrumentation have allowed experienced orthopaedic surgeons to perform total hip and total knee replacement surgery with surgical exposures that are less extensive than those associated with traditional techniques1,2. Commonly referred to as “minimally invasive total hip and total knee arthroplasty,” these techniques are now being touted as important surgical advancements. The introduction of minimally invasive total hip and total knee techniques has been accompanied by substantial concomitant changes in perioperative anesthetic techniques, rapid rehabilitation protocols, and changes in patient education and expectations. However, the specific contribution of each of these changes to observed improvements after contemporary total hip and total knee arthroplasty remains unclear. Tremendous strides in anesthesiology and perioperative pain management have been made with regard to the understanding of pain mechanisms and the importance of perioperative analgesia. The consequences of uncontrolled pain and medication-related side effects include the inability to actively participate in rehabilitation, delayed recovery, poor or suboptimal surgical outcome, prolonged hospitalization, and greater use of health-care resources3. Traditionally, the administration of intravenous opioids has been the mainstay for postoperative analgesia following total hip or total knee arthroplasty. However, parenteral opioids are commonly associated with inadequate pain relief, generalized sedation, and adverse side effects such as nausea, vomiting, gastrointestinal ileus, and pruritus. In response, some anesthesiologists have embraced the concept of “preemptive multimodal perioperative analgesia.” Preemptive analgesia involves the administration of analgesics prior to painful stimuli in order to prevent central sensitization and thus the amplification of pain4. Multimodal analgesia refers to the use of combined analgesic regimens for the treatment of postoperative pain. For example, low-dose opioids, local anesthetic infiltration, peripheral nerve blockade, nonsteroidal anti-inflammatory drugs, corticosteroids, clonidine, and cryotherapy all have been used in various combinations to manage postoperative …

Total knee arthroplasty in patients with isolated patellofemoral arthritis.

The current study evaluated the results of total knee arthroplasty for the treatment of isolated patellofemoral degenerative arthritis. Between 1980 and 1997, 31 total knee arthroplasties were done in 24 patients with advanced, isolated patellofemoral arthritis. The average followup was 5.2 years (range, 2–12 years). There was a significant improvement in the mean preoperative Knee Society pain and function scores. Twenty-one knees required a lateral retinacular release and three knees required additional formal proximal realignment at the time of the total knee arthroplasty. There were three reoperations in this series including, manipulation for poor motion in one patient; revision of a loose patellar component in one patient; and extensor mechanism realignment in the third patient. At midterm followup, total knee arthroplasty proved to be reliable and durable in alleviating pain and improving function in this group of patients with isolated, advanced patellofemoral arthritis. Surgeons should be made aware, however, that resurfacing of the patella and balancing the extensor mechanism for patients with isolated patellofemoral arthritis can be demanding technically as evidenced by the high rate of asymmetrically resurfaced patellas, the high rate of lateral retinacular release, and formal realignment procedures.