Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation.

In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g/cm2) was similar to that of young human bone (1.30 g/cm2) and significantly higher than that of elderly human cadaveric bone specimens (0.30 g/cm2). Cyclic loading was performed on free tendon grafts fixed with a bioabsorbable screw alone and on grafts fixed with a bioabsorbable screw and an anchor (polylactic acid ball or cortical bone disk). Stiffness of fixation increased substantially with the addition of a cortical bone disk anchor or polylactic acid ball compared with the interference screw alone. Tensile fixation strength of central quadriceps free tendon and hamstring tendon grafts were significantly superior in porcine bone of density similar to young human bone than in elderly human cadaveric bone. The bioabsorbable interference screw yielded loads at failure comparable with traditional bone-tendon-bone and hamstring tendon fixation when controlled for bone density. The addition of a cortical bone disk anchor provided the most optimal fixation of free tendon with the bioabsorbable screw and reduced slippage with cyclic loading to a very low level.

Resection of clinically localized segments of painful retinaculum in the treatment of selected patients with anterior knee pain.

We reviewed the long-term results of 25 patients who had localized soft tissue resections for refractory anterior retinacular knee pain. Patients completed visual analog scales to determine their activity and pain level changes, subjective assessment of their results, and whether they would have the surgery again under the same circumstances. Five of the 25 patients (20%) had had no knee surgery before the soft tissue excision, with the rest having had an average of two prior operations (range, 1 to 6). Subjectively, 22 patients (88%) noted moderate-to-substantial improvement after surgery; 3 patients (12%) declared no long-term benefit. All 25 patients stated that they would repeat the surgery under the same circumstances. Five patients (20%) noted a decrease in their results over time, but only two patients (8%) decreased their job level after surgery because of their knee pain. The average activity level dropped 60% after knee symptoms developed and increased 40% after surgery. Pain levels decreased 50% after surgery. The patients with the best overall results had lesions that were in the medial, inferomedial, or inferolateral retinaculum. The histologic results of the specimens included fibrosis, vascular proliferation, and small nerves with decreased myelin (neuromata). Our results show that specific soft tissue excision of painful tissue can often lead to successful clinical outcomes.

Anterior knee pain in females.

There are clear differences between men and women regarding anterior knee pain. Anatomic factors including increased pelvic width and resulting excessive lateral thrust on the patella are primary factors that predispose females to anterior knee pain. Effects of estrogen on connective tissue synthesis have been reported, but there is no clear mechanism by which this would affect anterior knee pain. Postural and sociologic factors such as wearing high heels and sitting with legs adducted can influence the incidence and severity of anterior knee pain in women.

The female knee--anterior knee pain.

There are clear differences between men and women with regard to anterior knee pain. Anatomic factors including increased pelvic width and the resulting excessive lateral thrust on the patella are significant in female predisposition to anterior knee pain. Effects of estrogen on connective tissue synthesis have been noted, but there is no clear mechanism by which this would affect anterior knee pain. Postural and sociologic factors such as wearing high heels and sitting with legs adducted can influence the incidence and severity of anterior knee pain in women.

Axial and lateral radiographs in evaluating patellofemoral malalignment.

This is a prospective study of 431 patients (862 knees) with patellofemoral pain, patellar dislocation, or other abnormalities of the knee joint. There were 217 asymptomatic knees with no contralateral problems for comparison. All patients had a history and physical and radiographic examination of both knees. The radiographs included standard anteroposterior views, axial views at 30 degrees of knee flexion, and standing lateral views at 0 degree and 30 degrees of flexion. The presence of patellar tilt or subluxation was noted on the axial view. The lateral view of the patella, with precise overlap of the posterior femoral condyles, allowed determination of relationships between the patella's medial edge, median ridge, and lateral edge to assess patellar tilt. Sixty-two percent of patients with patellar dislocations demonstrated subluxation on the axial view, while 98% demonstrated an abnormal lateral view. Eighteen percent of the control knees revealed evidence of subluxation on the axial view while 35% demonstrated subluxation on the extended lateral view. The axial view demonstrated 62% sensitivity for dislocation, while the lateral view taken in full extension demonstrated 98% sensitivity. The specificity for previous dislocation was 82% for the axial view and 93% for the lateral flexed view. Given the high sensitivity of the lateral view for detecting prior patellar dislocation, a normal result on this view can virtually eliminate the question of previous dislocation. Also, with the high specificity of the axial view and lateral view with knee flexion, the two views combined can confirm a clinical impression of patellofemoral malalignment.

The effects of bone plug length and screw diameter on the holding strength of bone-tendon-bone grafts.

The effect of bone plug length and Kurosaka screw (DePuy, Warsaw, IN) diameter on graft holding strength of the bone-tendon-bone construct was determined. Random length porcine bone plugs were assigned to fixation with 7 or 9 mm Kurosaka screws. Peak load to failure was determined. There was a significant decrease in peak load to failure of the 5-mm long bone plugs compared with longer bone plugs. No difference was found between longer lengths of bone plug in either the 7- or 9-mm screw diameter groups. The 9-mm diameter screws significantly increased peak load to failure for both 1- and 2-cm bone plug lengths.

Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer.

This retrospective study determined that the outcome from anteromedialization of the tibial tubercle correlates well with the location of patellar articular lesions. Detailed descriptions of patellar articular cartilage lesions were obtained from the operative reports of 36 patients who had anteromedialization performed between February 1984 and March 1994. The patterns fell into four distinct groups. Ten patients with type I (distal) patellar lesions and 13 patients with type II (lateral facet) patellar lesions had 87% good to excellent subjective results, and 100% of these patients said they would have the procedure done again. Nine patients with type III (medial facet) lesions had 55% good to excellent results, and 5 patients with type IV (proximal or diffuse) lesions had only 20% good to excellent results. Patients with type I or II lesions were significantly more likely to have good or excellent results than those with type III or IV lesions. Central trochlear lesions were associated with medial patellar lesions and all patients with central trochlear lesions had poor results. There was no significant correlation between the Outerbridge grading of the patellar lesion and the overall results. Workers' compensation issues diminished the likelihood of a satisfactory outcome by 19%; however, this was not statistically significant. This is the first study to correlate the patellar articular cartilage lesion with outcome after tibial tubercle transfer.

Fracture of the proximal tibia with immediate weightbearing after a Fulkerson osteotomy.

The records of 234 people who had anteromedialization of the tibial tubercle with oblique osteotomy between 1983 and 1994 at two separate institutions were reviewed retrospectively. Six patients (2.6%) had fractures of the proximal tibia postoperatively, within 13 weeks of the Fulkerson osteotomy. All fractures occurred after a change in the postoperative physical therapy regimen from partial weightbearing to immediate full weightbearing. All fractures healed with acceptable alignment of less than 5 degrees of varus-valgus or anteroposterior angulation. Given this increase in fracture incidence, a more conservative postoperative physical therapy regimen is recommended. All patients should be nonweightbearing initially, advanced gradually to partial weightbearing, and allowed full weightbearing only after the osteotomy has radiographic evidence of complete healing.

Arthroscopy of the patellofemoral joint.

There are multiple causes of patellofemoral pain that can be difficult to differentiate. A careful history and physical examination along with appropriate radiographic evaluation lead to the correct diagnosis in most cases. Most patients respond to a comprehensive nonoperative program that emphasizes stretching and strengthening of the quadriceps mechanism. Arthroscopy should be used judiciously when approaching patellofemoral problems. Regarding alignment, arthroscopy offers little benefit but may provide visualization for lateral release to relieve tilt. Arthroscopy of the patellofemoral joint does provide valuable information about articular cartilage breakdown location, extent, and pattern, which may help with future treatment decisions. Arthroscopy is helpful in the diagnosis and treatment of plicae and in ruling out other intraarticular causes of knee pain.

An alternative cruciate reconstruction graft: the central quadriceps tendon.

The central quadriceps tendon, above the patella, is thicker and wider than the patella tendon. Using precise technique, one can obtain a tendon graft for cruciate reconstruction with 50% greater mass than a patellar tendon bone-tendon-bone graft of similar width. The central quadriceps tendon graft may be harvested by a second surgeon while the first surgeon is simultaneously accomplishing notch-plasty and tunnel placement for cruciate ligament reconstruction. Consequently, this cruciate ligament reconstruction graft offers time savings as well as greater tendon volume. The central quadriceps tendon graft is difficult to harvest, with significant risk of entering the suprapatellar pouch and losing knee distension during ACL reconstruction. By careful adherence to the technique described in this article, the surgeon can obtain this reconstruction graft safely. It is important to recognize the anatomic subtleties of the proximal patella, which include a curved proximal surface, dense cortical bone, and closely adherent suprapatellar pouch. Proper technique is of utmost importance in obtaining this tendon graft safely and efficiently.

Differential diagnosis in patients with disorders of the patellofemoral joint.

Anterior knee complaints are difficult diagnostic problems. It cannot be overstated that the most important information available is to be found in the patient's history. Onset, quality, and quantity of symptoms must be assessed. This information is then synthesized to determine the specific functional disabilities resulting from the patient's anterior knee disorder. Once a history is obtained, a consistent, methodical physical examination can be performed to narrow the differential diagnosis. Radiographic evaluation is used to further hone the differential or to confirm the most likely diagnosis. Ultimately, a specific working diagnosis is selected and treatment is tailored to changing the underlying structural or biomechanical abnormalities that led to the patient's complaints.

Anterior knee pain--a symptom not a diagnosis.

A careful history and physical examination are the cornerstones of consistently successful diagnosis and treatment of anterior knee pain symptoms. Nonoperative treatment must be based on physical examination findings and should include both flexibility and strengthening. If an extended conscientious trial of nonoperative therapy fails to produce improvement, properly selected surgical procedures produce improvement in over 80% of cases. Realignment procedures, including lateral release, should only be proposed when malalignment can be documented. Although anterior knee pain has been called the "low back pain of the knee" by frustrated clinicians, effective treatment is likely when these principles are employed.

Distal realignment of the patellofemoral joint. Indications, effects, results, and recommendations.

Effective treatment of patellofemoral malalignment is possible with precise diagnosis. This precision must begin with a thorough history and physical examination. Both nonoperative and operative treatment are guided by the specific patterns identified. Distal realignment procedures including anteromedial tibial tubercle transfer necessitate meticulous surgical technique to achieve maximal benefit with a low rate of complications.

Preoperative computed tomography scanning and arthroscopy in predicting outcome after lateral retinacular release.

We initiated a study to look at preoperative, flexed-knee, midpatellar computed tomography (CT) scans and intraoperative arthroscopic findings of lateral patellar articular degeneration in predicting the results after lateral retinacular release for failed nonoperative treatment of anterior knee pain. Twenty patients with 30 painful knees underwent preoperative flexed-knee, midpatellar CT scans that were retrospectively classified by the method of Fulkerson into normal alignment, lateral subluxation, lateral patellar tilt, and combined tilt and subluxation. Arthroscopy was performed before open lateral release. The lateral facet of the patella was graded as either minimal changes (Outerbridge I or II) or advanced (Outerbridge III or IV) changes. Patients were followed for a minimum of 2 years and graded on a standard patellofemoral rating scale. Only 22 of 30 knees that were thought to be clinically malaligned, actually were malaligned by CT scan; eight CT scans were interpreted as normal. The results were further stratified into group A (CT-documented tilt, minimal facet changes), group B (CT-documented tilt, advanced facet changes), and group C (normal CT). Ninety-two percent of group A were rated good or excellent. Twenty-two percent of Group B rated good/excellent, 33% fair, 44% poor. Only 13% of group C rated good (one patient). Based on the results of the study, we recommend lateral release for anterior knee patients with CT-proven patellar tilt who have not responded to conservative treatment and have minimal facet changes with minimal or no subluxation. Lateral retinacular release should not be offered as a treatment to the patient with a normally aligned patella because poor results will most likely result.

Comparison of initial pull-out strength of arthroscopic suture and staple Bankart repair techniques.

This study was performed to investigate the initial failure strength of arthroscopic suture and staple techniques use to treat recurrent anterior shoulder instability. Eight canine shoulder complexes were fashioned so that four 1-cm wide strips of capsule remained attached to the glenoid in each specimen (total of 32 test specimens) these specimens were tested to tensile failure on an Instron model 1331 testing machine either intact (n = 5), or after the capsule was sharply dissected off the bone and repaired with an arthroscopic staple (n = 11) or arthroscopic suture technique (n = 12). The control group failed at 17.75 +/- 7.14 kg, the suture repair at 11.0 +/- 2.56 kg, and the staple repair at 4.77 +/- 2.32 kg. These failure strengths were all statistically different from each other (p less than 0.0001). All failures occurred at the capsular bone interface. The authors do not advance one technique over the other but do advise surgeons to be mindful of the results when instituting early shoulder motion after arthroscopic Bankart procedures.

Operative management of patellofemoral pain.

In short, the surgical treatment of patients with patellofemoral pain will depend on understanding each specific disorder and the pattern of articular degeneration. Tilt alone generally responds well to lateral release. Subluxation, particularly when more severe, may require medial imbrication and/or a distal (Trillat) procedure in addition to lateral release to achieve extensor mechanism balance. When there is significant patellar arthrosis, an oblique osteotomy deep to the tibial tubercle will permit unloading of the patellar articular surface in addition to realignment. A small amount of metaphyseal bone placed in this oblique osteotomy will permit straight anterior displacement of the tibial tubercle of 15-20 mm with minimal bone graft when necessary. These basic surgical procedures will permit adequate treatment of most patients with resistant patellofemoral pain (with or without arthrosis) when non-operative measures have failed and the appropriate procedure is selected for a specific mechanical disorder.