Paul J. Duwelius

Minimally invasive total hip arthroplasty development, early results, and a critical analysis

Hip replacement with use of small incisions has been practiced selectively by a few practitioners for many years, but only in the last several years has so-called minimally invasive hip replacement been widely introduced to the majority of orthopaedic surgeons. Minimally invasive hip replacement, in fact, is not a single type of surgery but rather is a family of operations designed to allow total hip replacement to be done through smaller incisions, potentially with less soft-tissue disruption. The three main methods involve a combination of a small incision and a posterior approach to the hip, a combination of a small incision and an anterior approach to the hip, or two small incisions performed with use of the Smith-Peterson interval for acetabular placement and the approach usually used for femoral intramedullary nailing for femoral component insertion. Minimally invasive total hip arthroplasty has created much controversy among orthopaedic surgeons and a great deal of publicity in the popular press. Advocates emphasize the potential for these methods to reduce soft-tissue trauma and thereby reduce operative blood loss, postoperative pain, and hospitalization time; speed the postoperative recovery; and improve the cosmetic appearance of the surgical scar. Advocates view minimally invasive total hip arthroplasty as a logical extension of less invasive methods that have revolutionized other fields, such as arthroscopy, laparoscopic cholecystectomy, and cardiac surgery, just to name a few. Those with reservations about minimally invasive total hip replacement point out that conventional hip replacement already provides excellent pain relief, functional improvement, and durability with a low complication rate. Skeptics are concerned that minimally invasive procedures introduce new potential problems related to reduced visualization at the time of the operation, such as implant malposition, neurovascular injury, poor implant fixation, or compromised long-term results. Advocates of minimally invasive methods believe that minimally invasive hip arthroplasty holds …

A technique for intramedullary nailing of proximal third tibia fractures

Twelve of 14 proximal third tibial shaft fractures were successfully treated with a new technique for intramedullary nailing of these fractures. The average anterior displacement was 3.0 mm (range 0-17). The average coronal plane alignment was 2.0 degrees valgus (range 2 degrees varus to 12 degrees valgus). There was one nonunion. The techniques success is dependent on neutralizing the primary factors causing malreduction: wide effective diameters of tibial nails, narrow diameter of the medial tibial metaphysis, and a posteriorly directed sagittal plane entrance angle.

The two-incision minimally invasive total hip arthroplasty: technique and results

Minimally invasive surgery has the potential for minimizing surgical trauma, pain, and recovery time in patients having THA. This minimally invasive two-incision total hip technique was found to be safe and facilitated a rapid patient recovery. Further-more, unique instruments and fluoroscopic assistance ensure accurate component position and alignment. This technique is technically challenging, however; as such, proper training, including cadaveric training, is essential to minimize complications and ensure success.

Internal fixation of displaced fractures of the sacrum

The results of internal fixation in 30 patients with displaced fractures of the sacrum were retrospectively reviewed. All fractures were displaced at least 1 cm. Neurologic injuries occurred in 40% (12 of 30) patients. In 17 patients who underwent open reduction, the preoperative displacement averaged 24 mm and the postoperative displacement averaged 4 mm. In the 13 patients in whom percutaneous fixation was done, the preoperative displacement averaged 15 mm and the postoperative displacement averaged 5 mm. All 30 fractures united. This review of 30 patients with displaced sacral fractures suggests that open reduction and iliosacral screw fixation leads to better reduction of the fracture site than does closed reduction and percutaneous fixation. Functional assessment indicated that the presence of a neurologic injury is the most important predictor of compromised outcome in patients with displaced sacral fractures.

The Effects of Femoral Intramedullary Reaming on Pulmonary Function in a Sheep Lung Model

Two methods of intramedullary fixation of fractures of the middle of the femoral shaft were evaluated in a sheep model to determine the effect of femoral reaming on pulmonary function. The effect of a modified reamer was also studied. A second experiment with the same model was performed to evaluate the relationship between embolization and pulmonary dysfunction. This experiment involved two groups of sheep—those with normal lungs and those with contused lungs—divided into subgroups—those that had nailing with reaming and those that had nailing without reaming. Intracardiac ultrasound was used to measure the magnitude and duration of transvenous particulate embolization during the operations. Both experiments involved hemodynamic monitoring during and after the nailing. The pulmonary tissue was examined histologically after the animals were killed. The hemodynamic monitoring revealed only a transient increase in pulmonary vascular resistance in the animals that had femoral nailing with reaming in both experiments. The modified reamer had no effect on the pulmonary response. Histological analysis of pulmonary tissue demonstrated a significant increase in the number of fat emboli in both the animals that had nailing with reaming and the animals that had nailing without reaming compared with the control animals. Intravascular ultrasound revealed that the operative maneuver associated with the greatest number of emboli was opening of the intramedullary canal with the awl. The first two passes of the reamer produced more emboli and embolism of longer duration than did the later passes. Pulmonary contusion did not increase the risk of pulmonary dysfunction due to intramedullary nailing in this model. CLINICAL RELEVANCE: Pulmonary dysfunction as a result of intramedullary nailing was minimum in our fracture model. There was no significant difference, between the animals that had reaming and those that did not have reaming, with regard to the adverse effects on pulmonary function. Reaming had a minor transient effect on pulmonary vascular resistance that was not seen in the animals that did not have reaming. The minor pulmonary effects in the two groups were not worsened by the presence of a pulmonary contusion. We concluded that, with regard to their effects on pulmonary function, there was no distinct advantage either to nailing with reaming or to nailing without reaming for fractures of the femoral shaft.

Treatment of tibial plateau fractures by limited internal fixation

Seventy-five adults who sustained 76 tibial plateau fractures were treated according to a prospective protocol using instability in extension as the principal indication for operative fixation. Patients showing instability underwent closed manipulative reduction under fluoroscopic guidance. If significant joint depression persisted after reduction, elevation of the fracture was performed either from below using bone punches through a cortical window or via limited arthrotomy. Iliac crest bone graft was used to buttress depressed fractures. Fixation was then secured using 7-mm cannulated screws with washers or buttress plates and screws. Postoperatively, 58 of 76 knees were managed in a hinged knee brace, allowing the patient early range of motion and protected weightbearing for 8 weeks. Patients who were found to have a stable knee were treated with Bledsoe braces according to the postoperative protocol. In the 75 patients, 18 of the 76 knees were unsuitable for percutaneous screw fixation because of fracture complexity requiring plates, severe open injuries, or inadequate reductions with limited fixation had been done. A minimum followup of 12 months was obtained in 55 patients (range, 12-59 months). All fractures had healed at the time of followup. Eighty-seven percent of the patients at followup had a successful outcome using Rasmussens criteria. Fourteen of these patients had arthroscopic assisted reduction or evaluation. All seven patients who had poor outcomes had AO Type C3 fracture patterns. Severely depressed or comminuted fractures or fractures with significant metaphyseal diaphyseal extension may not be suitable for this technique and require the addition of an external fixation device or buttress plate to maintain the reduction and allow for early range of motion.

Resonant frequency analysis of the tibia as a measure of fracture healing.

Summary: The Resonant Frequency (RF) of the tibia is proportional to its stiffness. As a fractured tibia heals, its RF should increase. The RF was serially determined in 74 fractured tibias (205 examinations). These were subdivided by fracture location and fixation. Fast Fourier transform software generates the RF from data obtained with an instrumented impactor and accelerometer. The RF was normalized by expressing it as a ratio of the intact tibia. This ratio is called the tibial stiffness index (TSI). A 20 point tibial fracture score (TFS) quantitated the clinical and radiographic signs of healing. For each group the paired TSI and TFS were compared by regression analysis. Except for those fractures limited to the proximal fourth of the tibia, the TSI was found to correlate significantly (p=0.0001) with the TFS. Fractures without fixation and those with unlocked, unreamed tibial nails showed very significant correlation of TSI with TFS (p=0.0001). RF analysis was not useful in fractures with locked or reamed tibial nails. Examination of tibia with external fixation showed significant correlation (p=0.02) of the TSI with the TFS

Closed reduction of tibial plateau fractures. A comparison of functional and roentgenographic end results.

One hundred tibial plateau fractures in 96 patients were treated at three teaching hospitals. Seventy-three fractures were treated by closed reduction and early mobilization of the knee using a cast brace. Twelve fractures in this group also had percutaneous pin fixation under fluoroscopic control. The end results were graded by clinical functional criteria and by roentgenographic criteria. Eighty-nine percent of the patients treated by closed reduction methods had good to excellent functional results with a low complication rate (12%). Observations based on long-term roentgenographic examinations did not correlate with the functional end results. Many patients with less than satisfactory roentgenographic results had good to excellent functional long-term results. The indications for operative stabilization of these fractures should be based on testing for knee stability in full extension, rather than on any arbitrary roentgenographic criteria. For unstable fractures, closed reduction using ligamentotaxis and percutaneous fixation supplemented by cast brace support proved effective and relatively free of complications.

Synovial cyst formation complicating total hip arthroplasty: a case report.

The most frequent causes of unilateral limb swelling unrelated to trauma or surgery are deep venous thrombosis, chronic venous insufficiency, and primary lymphedema. Other important but less frequent causes include infection and neoplasm. Neoplasms may cause limb swelling, either by soft tissue enlargement or incidental compression of venous or lymphatic structures. Reported here is an unusual case of a patient with unilateral leg swelling and an inguinal mass presenting years after total hip arthroplasty. The unilateral leg swelling was caused by compression of the right common femoral vein by a synovial cyst arising from the hip joint. Although only 2 cases have been described in the literature, such cyst formation is not uncommon with loose acetabular components. The most apparent cause of cyst formation was polyethylene debris. Treatment efforts should be directed at the source of the debris intraarticularly.

Nonreamed interlocked intramedullary tibial nailing. One community's experience.

Forty-nine acute displaced tibial fractures (31 closed, 18 open: 5 Grade I, 7 Grade II, 4 Grade IIIA, and 2 Grade IIIB) were treated in 1 community with a standard operative protocol using a distractor without a fracture table, and an unreamed interlocked tibial nail. Forty-six fractures healed (94%). Complications included 3 nonunions (6%), 2 deep infections (4%), 9 delayed unions (18%), 4 angular malunions (8%), 2 rotatory malunions (4%), and 12 interlocking screws bent or broke (24%). Twenty-eight patients (57%) required at least 1 additional operation to obtain union, most commonly dynamization of a statically locked nail. The authors conclude that unreamed tibial nails provide adequate stabilization of displaced tibial fractures and can be used in the management of most open or closed tibial fractures. However, static locking is required in axially unstable fractures. Early dynamization or exchange nailing and bone grafting should be considered to hasten union and avoid screw failure. The distractor is an excellent adjunctive technique for reduction and alignment of tibial shaft fractures during intramedullary nailing.