A ported, proximally-cemented femoral stem for total hip arthroplasty. Development and clinical application.

We describe the development and early clinical application of a ported, proximally-cemented titanium stem for cemented total hip arthroplasty. PMMA bone cement is delivered to the proximal femur under pressure after the stem has been positioned within the femoral canal. A mid-stem cement occluder contains the cement to the proximal stem only. A tapered body is incorporated in the design of the stem to reduce the structural stiffness and hence the degree of stress shielding within the reconstructed joint. We performed preclinical studies to measure the reduction in porosity and the pressurisation achieved. The porosity, as measured by the void percentage within the cured cement mantle, was reduced by more than 50% and there was an almost threefold increase in the mean pressure. Mechanical testing of the stem, using a three-point bend test, showed that the addition of cement injection ports on the anterior and posterior sides of the body of the proximal stem did not reduce its strength. Finite-element analysis indicated that, compared with a fully-cemented conventional stem, there was no change in the stresses within the cement mantle. In a series of 40 proximally-cemented stems followed for up to six years (mean 51 months) the mean Harris hip score was 91, and 85% of patients had good or excellent results. There was excellent pain relief, an increased level of activity and good patient satisfaction. One mechanical failure of the stem required revision at three years after implantation. The early results indicate that the clinical performance was equal to that achieved with other modern cemented stems. Radiological evaluation showed excellent results with no evidence of stress shielding. Further follow-up will determine if long-term stress shielding is reduced and if revision is made easier by the absence of a distal cement mantle.

Ipsilateral knee injury with femoral fracture. Examination under anesthesia and arthroscopic evaluation.

Forty adults with closed diaphyseal femoral fractures and no previous knee injury were prospectively studied to determine the incidence of concomitant ipsilateral extra- and intraarticular knee injury. After intramedullary nailing, examination under anesthesia and arthroscopy were performed. The mechanism of injury was high-energy trauma. Femoral fixation included 30 interlocked nails. The results of the examination showed laxity > Grade I in 52.5% of the patients. Significant arthroscopic findings included 19 partial (48%) and two complete (5%) anterior cruciate injuries; two partial (5%) and one complete (2.5%) posterior cruciate injuries; and five medial (12%) and eight lateral (20%) meniscus tears. Significant arthroscopic findings (anterior cruciate ligament or posterior cruciate ligament injuries, meniscal tear, osteochondral fracture) were noted in conjunction with effusion or laxity > Grade I in more than half of the group, and such findings were present in one third despite absence of effusion or laxity. This study documented the incidence and array of findings noted at arthroscopy. In all, 22 patients (55%) had significant arthroscopic findings. A high incidence of knee injuries, including many that were occult, occurred in conjunction with ipsilateral femoral shaft fractures. Based on these findings, the authors recommend a high index of suspicion for coexisting knee injuries with ipsilateral femoral fracture and use of appropriate diagnostic and therapeutic measures.

Meniscal injury associated with femoral shaft fractures. An arthroscopic evaluation of incidence.

We studied 47 patients with closed, displaced, diaphyseal fractures of the femur caused by blunt trauma, to determine the incidence of associated knee injuries, particularly of the meniscus. After femoral nailing, all patients had an examination under anaesthesia and an arthroscopy. There were 12 medial meniscal injuries (5 tears) and 13 injuries of the lateral meniscus (8 tears). Ten of the 13 tears were in the posterior third of the meniscus, and two patients had tears of both menisci. Synovitis was common at the meniscal attachments. Complex and radial tears were more common than peripheral or bucket-handle tears. Examination under anaesthesia revealed ligamentous laxity in 23 patients (49%), but meniscal injuries had a similar incidence in knees with and without ligament injury. Femoral shaft fractures are often associated with injuries to the ipsilateral knee, and a high index of suspicion is necessary to identify these lesions.

Total knee replacement after fractures about the knee.

We reviewed 17 cases of posttraumatic arthritis after fractures about the knee. All patients underwent total knee replacement; one had a distal femoral osteotomy to correct a deformity prior to arthroplasty. Thirteen patients had a minimum one-year follow-up, with an average follow-up of 27 months (range, one to four years). Of these, eight were considered to have a successful clinical result. All five patients with unsuccessful results had major intraoperative and/or postoperative complications. In malunions of intra-articular fractures of the proximal tibia, the important technical consideration for planned total knee replacement is preoperative tilt of the tibial plateau in the antero-posterior (AP) and lateral radiographic views. Tibial plateau tilt should be recognized during preoperative planning, and intraoperative adjustments are required. In malunions of extra-articular fractures of the distal femur or proximal tibia, a varus or valgus deformity is an important consideration. Prearthroplasty osteotomy may be considered in a patient with a significant bony deformity above or below the joint line. Incisions should be carefully planned, especially when a previous lateral distal femoral approach has been performed. The results may resemble revision rather than primary arthroplasty.

Displaced acetabular fractures.

Displaced acetabular fractures occur primarily in young adults involved in high energy trauma and can lead to disabling posttraumatic arthritis. An initial roentgenographic evaluation with accurate delineation of all fracture lines provides the key to decisions about whether to give closed or open treatment. When open treatment is indicated, a surgical approach can be chosen that will almost always lead to reduction without the necessity of a second approach. The authors have found that the Kocher-Langenbeck, ilioinguinal, and extended iliofemoral approaches are the most useful. A fracture table and specialized reduction instruments aid fracture reduction and fixation. Satisfactory operative reduction of the fracture is the factor that correlates best with a satisfactory clinical result. The rate of satisfactory operative reductions improved gradually over the first 50 operations of a prospective study of 121 displaced acetabular fractures. Overall, there were 80% satisfactory clinical results in this series. Complications included a 3% infection rate and a 5% incidence of nerve palsy. Open reduction and internal fixation are indicated for the majority of displaced fractures. However, closed treatment can produce satisfactory results in selected patients.

Immediate internal fixation of open ankle fractures.

Seventy-six consecutive displaced open ankle fractures were treated by immediate internal fixation between 1983 and 1986 at Los Angeles County University of Southern California Medical Center. Sixty-two patients were available for clinical and radiological examination at an average of 16.4 months post-fixation. Seventy-two percent of the patients had a satisfactory result. Poor results (20%) were most commonly due to non-anatomic reductions, articular surface damage, or deep infection. Deep infection occurred in 5% of the patients while 8% required late ankle arthrodesis. We believe immediate internal fixation is the treatment of choice for displaced open ankle fractures, but this form of treatment does have a significant rate of complications.