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Biomedical subjects

P A Keblish

Publications and source records attributed to P A Keblish.

12 recordsLinked to original sources
PubMed2006

Femoral component rotation in mobile-bearing total knee arthroplasty.

The surgical technique utilized for the LCS mobile-bearing since 1977 has been a tibial cut first method which requires determination of femoral rotation with tension spacing. We evaluated 38 randomly selected mobile-bearing TKA in which this technique was utilized. All cases had satisfactory clinical results. Spiral computed tomography scans measured the posterior condylar angle which is the angle of the femoral component posterior condyles in relation to the surgical transepicondylar axis. The mean femoral component alignment was 0.3 degrees of internal rotation to the transepicondylar axis (S.D.=2.2 degrees ; range=6 degrees internal to 4 degrees external). Four cases (10%) were outside of 3 degrees from the TEA. Lateral patellar tilt and subluxation was identified in one female who had a femoral component position of 5 degrees internal rotation. In 90% of cases, the posterior condylar angle was within 3 degrees of the surgical transepicondylar axis which is regarded as the functional ideal for conventional methods.

Aged↗
PubMed2001

Kinematics of the patellofemoral joint in total knee arthroplasty.

Sagittal plane patellofemoral kinematics was determined for 81 subjects while performing a weight-bearing deep knee bend under fluoroscopic surveillance. Fourteen normal knees, 12 anterior cruciate ligament (ACL)-deficient knees, and 55 total knee arthroplasties (TKAs) were assessed. Of TKAs, 39 had resurfacing with a dome-shaped patella, 8 had resurfacing with an anatomic mobile-bearing patella, and 8 were unresurfaced. TKA patellae experienced more superior patellofemoral contact and higher patellar tilt angles compared with the normal knees and ACL-deficient knees (P <.05). Patellofemoral separation at 5 degrees (+/-3 degrees ) extension was seen in 86% cruciate-retaining and 44% cruciate-stabilized TKAs and 8% ACL-deficient knees but not in the normal knees or mobile-bearing TKAs (P <.05). The patellar kinematic patterns for subjects having a TKA were more variable than subjects having either a normal knee or an ACL-deficient knee. Kinematic abnormalities of the prosthetic patellofemoral joint may reduce the effective extensor moment after TKA.

Anterior Cruciate Ligament↗
PubMed2000

In vivo kinematic comparison of posterior cruciate ligament retention or sacrifice with a mobile bearing total knee arthroplasty.

Video fluoroscopy and computer photogrammetry was used to evaluate 20 knees with posterior cruciate ligament (PCL) retaining and 19 knees with PCL sacrificing total knee arthroplasties (TKAs) with a mobile bearing total condylar prosthesis compared with 10 normal patients. In extension, femorotibial contact was posterior for TKA patients (P<.05) and demonstrated anterior translation from 60 degrees-90 degrees flexion. However, posterior rollback with limited translation was seen from 0 degrees-40 degrees, which may reflect the high congruity of this prosthesis. Fifty percent of meniscal bearing implants demonstrated bearing translation. Kinematics and weight-bearing range of motion were similar with PCL retention or sacrifice.

Aged↗
PubMed1997

In vivo kinematic analysis of a mobile bearing total knee prosthesis.

Ten normal subjects and 10 patients with a posterior cruciate retaining mobile bearing total knee replacement performed successive deep knee bends under fluoroscopy to determine tibiofemoral contact positions. At full extension the average initial contact position for the normal and mobile total knee replacement was 6.2 mm (range, 4.8 to 12 mm) anterior, and -4.4 mm (range, 3.9 to 11 mm) posterior to the sagittal tibial midplane, respectively. At 60 degrees flexion, the normal knee rolled back to -5.8 mm (range, -2.5 to -13.2 mm), whereas the mobile bearing total knee replacement rolled back to -9.2 mm (range, -4 to -17 mm). From 60 degrees to 90 degrees, normal knees rolled back to -7.8 mm (range, -5.8 to -13.8 mm), but the mobile bearing total knee replacement slid anteriorly to -5 mm (range, 2 to -12 mm). All mobile bearing total knee replacements had some form of roll back, but some slid anterior more than others. Five of 10 mobile bearing total knee replacements had some movement of the bearings while the others remained fixed. Patellar kinematics was similar to normal but reflected tibiofemoral abnormalities.

Arthroplasty, Replacement, Knee↗
PubMed1994

Patellar resurfacing or retention in total knee arthroplasty. A prospective study of patients with bilateral replacements.

Patellofemoral problems are a common cause of morbidity and reoperation after total knee arthroplasty. We made a prospective study of 52 patients who had bilateral arthroplasty (104 knees) and in whom the patella was resurfaced on one side and not on the other. A movable-bearing prosthesis with an anatomical femoral groove was implanted on both sides by the same surgeon using an otherwise identical technique. The mean follow-up was 5.24 years (2 to 10). In the 30 available patients (60 knees) there was no difference between the two sides in subjective preference, performance on ascending and descending stairs or the incidence of anterior knee pain. Radiographs showed no differences in prosthetic alignment, femoral condylar height, patellar congruency or joint line position. The use of an appropriate prosthetic design and careful surgical technique can provide equivalent results after knee arthroplasty with or without patellar resurfacing. Given the indications and criteria, which we discuss, retention of the patellar surface is an acceptable option.

Adult↗
PubMed1991

The lateral approach to the valgus knee. Surgical technique and analysis of 53 cases with over two-year follow-up evaluation.

Valgus deformity correction poses a major challenge in total knee arthroplasty (TKA). The standard medial approach has many technical limitations and disadvantages that include patellofemoral maltracking and subsequent patellar problems. The lateral approach has been developed and utilized successfully in 79 cases (53 with over two-year follow-up evaluation) since 1980. The biomedical rationale of the approach is sound, and addresses the pathologic anatomy of fixed valgus deformity. Surgical technique is direct, anatomical, more physiologic, and maintains soft-tissue integrity. The "lateral release" is performed as part of the approach. Patellofemoral tracking and alignment stability are optimized and medial blood supply preserved. Clinical experience has shown the approach to be more aesthetic and results objectively superior. Scores have been good/excellent in 94.3% of cases. Knee stability is enhanced with the use of nonconstrained prostheses in this difficult group of patients. The lateral approach is recommended as the "approach of choice" for fixed valgus deformity in TKA.

Aged↗
PubMed1988

Restoration of the foot using the radial forearm flap.

Large foot defects unsuitable for reconstruction by local foot flaps are most expediently salvaged with distant free-tissue transfers. Although muscle flaps are preferred for infected wounds, coverage of the clean or acute foot deformity may be better achieved with the innervated radial forearm fasciocutaneous flap. This almost ideal donor site has been used by us for all traumatic foot defects requiring free flaps during the previous year. Our results document that in the 5 available clinical examples, restoration of normal foot contour, durability during ambulation, and an excellent aesthetic appearance were achieved.

Adolescent↗
PubMed1986

Amputation alternatives in the lower limb, stressing combined management of the traumatized extremity.

A methods approach for the care of the traumatic lower extremity amputee is presented, emphasizing joint surgical approach, specifics of management, ideal amputation levels, and functional rehabilitation. The role of the plastic surgeon with an interest in free flaps is ever increasing and has elevated the level and quality of traumatic extremity amputation. Therefore, an understanding by the plastic surgeon of the orthopedic, prosthetic, functional, and rehabilitation principles becomes as important as the orthopedic surgeon's appreciation of current microvascular reconstruction potential. Fortunately, large numbers of traumatic amputees are not available for study in the civilian population. With better-quality extremity salvage by free flap coverage, this number is decreasing. However, the problem will never be eliminated and efforts to produce the best possible amputation must be expended by the best techniques and personnel. Prosthetic management continues to develop with exciting innovations on the horizon. Currently, the modular concept of prosthetic design (Fig. 26) is a practical, cosmetic standard. Newer space-age materials and design changes should facilitate the functional potential of the traumatic amputee. Characteristics of traumatic lower extremity amputees are youth, immaturity, arrogance, and psychological instability, but they are usually cooperative following the initial shock and reality of the situation. These young people deserve our best efforts to allow them to become integrated into society and continue an active life, albeit passive or active (Fig. 27).

Amputation, Surgical↗