Biomechanical comparison of tibial inlay and tibial tunnel techniques for reconstruction of the posterior cruciate ligament. Analysis of graft forces

BACKGROUND: The tibial inlay technique of reconstruction of the posterior cruciate ligament offers potential advantages over the conventional transtibial tunnel technique, particularly with regard to the graft force levels that develop over a functional range of knee flexion. Abnormally high graft forces generated during rehabilitation activities could lead to stretch-out of the graft during the critical early healing period. The purpose of this study was to compare graft forces between these two techniques and with forces in the native posterior cruciate ligament. METHODS: A load cell was installed at the femoral origin of the posterior cruciate ligament in twelve fresh-frozen cadaveric knees to measure resultant forces in the ligament during a series of knee loading tests. The posterior cruciate ligament was then excised, and the femoral ends of 10-mm-wide bone-patellar tendon-bone grafts were attached to the load cell to measure resultant forces in the grafts. For the tunnel reconstruction, the distal bone block of the graft was placed into a tibial tunnel and thin stainless-steel cables interwoven into the bone block were gripped in a split clamp attached to the anterior tibial cortex. With the inlay technique, the distal bone block was fixed in a tibial trough with use of a cortical bone screw with a washer and nut. The proximal ends of all grafts were pretensioned to a level of force that restored intact knee laxity at 90 degrees of flexion, and loading tests were repeated. RESULTS: There were no significant differences in mean graft forces between the two techniques under tibial loads consisting of 100 N of posterior tibial force, 5 N-m of varus and valgus moment, and 5 N-m of internal and external tibial torque. Mean graft forces with the tibial tunnel technique were approximately 10 to 20 N higher than those with the inlay technique with passive knee flexion beyond 95 degrees. Mean graft forces with both reconstruction techniques were significantly higher than forces in the native posterior cruciate ligament with the knee flexed beyond approximately 90 degrees for all but one mode of loading. CONCLUSIONS: In this cadaveric testing model, neither technique for reconstruction of the posterior cruciate ligament had a substantial advantage over the other with respect to generation of graft forces.     

髌骨和髂骨移植修复膝部骨巨细胞瘤致大块骨缺损

目的 探讨髌骨和髂骨移植对股骨下端和胫骨上端大块骨缺损修复的治疗效果.方法 股骨下端和胫骨上端骨巨细胞瘤患者14例,男8例,女6例;年龄20～42岁,平均33.9岁;病史2～12个月,平均5.6个月;股骨下端6例,胫骨上端8例.按Ennecking外科分期,2期11例,3期3例.游离髌骨移植8例,带肌蒂髌骨移植2例,髂骨移植4例.股骨和胫骨肿瘤侵犯一侧髁软骨面时用游离或带肌蒂髌骨移植,胫骨肿瘤同时侵犯髁间部时用髂骨移植,修复和重建膝关节部骨缺损.结果 随访时间3个月～11年,平均4.5年.根据国际保肢学会功能评分标准,优3例,良8例,可2例,差1例.游离髌骨移植者关节功能较好.术后主要并发症为关节活动范围减小(活动范围,40°～120°,平均82°),关节不适,肌力下降,疼痛.带肌蒂髌骨移植者术后伸膝肌力有不同程度地下降,但随着时间的延长有一定的恢复.游离髌骨移植者术后伸膝肌力下降不明显.髂骨移植患者术后关节退行性改变明显.结论 膝关节周围骨巨细胞瘤侵犯关节软骨时,行包括肿瘤在内的股骨或胫骨一侧髁切除后,可以用髌骨和髂骨移植修复和重建骨缺损.     

Autogenous bone grafting for severe angular deformity in total knee arthroplasty

Fourteen patients with severe angular knee deformities (range, 30 degrees varus to 35 degrees valgus) had total knee arthroplasty using autogenous bone graft to the tibia. Twelve knees had osteoarthritis, one rheumatoid arthritis, and one gouty arthritis. The preoperative knee motion averaged -5 degrees of extension to 80 degrees of flexion and the average motion arc was 70 degrees. All tibial defects were greater than 25% of the tibial component support surface and more than 10 mm deep. Twelve knees were reconstructed with Insall-Burstein posterior stabilized total condylar knee implants and two knees, with severe preoperative ligamentous instability, with the constrained Total Condylar III implant. Postoperative rehabilitation was routine, and weight bearing was begun, on average, on the third postoperative day. The follow-up period averaged 4.1 years (range, 2-7.3 years). Radiographic analysis revealed no change in knee or component alignment compared with immediate postoperative position. All grafts consolidated without evidence of collapse, resorption, or prosthetic subsidence. All patients had good or excellent clinical results (Hospital for Special Surgery Knee Rating Scale). The average postoperative arc of motion was 90 degrees. There were no infections and no need for implant removal. The technique developed by the senior author (T.P.S.) utilizes bone resected from the distal femur during knee arthroplasty. An oblique planar cancellous surface is created on the recipient side, and coaptation of cancellous distal femoral graft surface to this recipient bed is ensured by vitallium screw fixation. The proximal tibia is reconstituted by the graft, and subchondral femoral bone after shaping of the graft forms the tibial periphery.     

The results of primary total knee arthroplasty with bone stock restoration by autologous grafts from resected bony ends]

AIM OF THE STUDY: The aim of the study is the comparison of results of primary total knee arthroplasty with large bone stock deficiencies treated with autologous bone grafts from resected joint ends (both solid and morselized) with the group of patients in whom knee arthroplasty was made without the need of bone grafting. MATERIAL AND METHOD: 342 primary total knee replacements implanted till the end of 2004 at Orthopaedic and Traumatology Department in Lublin were examined. Bone stock defects were treated in 37 knees (35 patients). The necessity of reconstruction resulted from destruction of knee joint surfaces in advanced degenerative osteoarthritic processes or rheumatic disease. Autologous solid bone grafting was used in 22 knees, morselized in 13, meanwhile 2 different required both types of grafts. The medial tibial condyle bone stock defects were the most frequent--26 knees. Control group consists of 39 knees in 33 patients treated in the same period without the need for bone grafting and prostheses were implanted directly on resected surfaces. Preoperative and postoperative knee function was established with Hospital for Special Surgery Score (HSS). The X-rays were analyzed with the special regard for: correctness of implants placing, presence of radiolucence zones both around implants and grafts, and bone grafts healing. RESULTS: The analysis of subsequent X-rays showed bone grafts healing (both solid and morselized) in 21 knees. In 4 knees progressive bone grafts lysis was observed. The remaining knees showed the presence of grafts and lack of evidence of healing in surrounding host bone. No differences were observed in number of intra- and postoperative complications, radiographic knee replacements geometry and long-term clinical results in both groups of patients. CONCLUSIONS: 1) Results of total knee replacements with autologous bone grafting for bone stock reconstruction are comparable with the results of TKR without the need for bone grafting. 2) Natural harvesting of the graft material from resected joint ends and effectiveness of reconstruction increase the value of the method. 3) The durability of early good results need further examination.     

Effects of notchplasty and femoral tunnel position on excursion patterns of an anterior cruciate ligament graft

Purpose: Errors in femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction can cause excessive length changes in the graft during knee flexion and extension, resulting in graft elongation during the postoperative period. To improve the accuracy of tunnel placement and to avoid graft impingement, a notchplasty is commonly performed. The purpose of this study was to determine the effects of varying the position of the femoral tunnel and of performing a 2-mm notchplasty of the lateral femoral condyle and roof of the intercondylar notch on excursion patterns of a bone–patellar tendon–bone graft. Type of Study: Biomechanical cadaveric study. Methods: A cylindrical cap of bone, containing the tibial insertion of the ACL, was mechanically isolated in 15 fresh-frozen cadaveric specimens using a coring cutter. The bone cap was attached to an electronic isometer that recorded displacement of the bone cap relative to the tibia as the knee was taken through a 90° range of motion. After native ACL testing, the proximal end of a 10-mm bone–patella tendon–bone graft was fixed within femoral tunnels drilled at the 10-, 11-, and 12-o'clock (or 2-, 1-, and 12-o'clock) positions within the notch. The distal end of the graft was attached to the isometer. Testing was then completed at each tunnel position before and after notchplasty. Results: Before notchplasty, mean graft excursions at the 10- or 2-, 11- or 1-, and 12-o'clock tunnels were not significantly different from the excursions of the native ACL or each other. After a 2-mm notchplasty, mean graft excursions at the 3 tunnel locations were not sigificantly different from each other but were greater than mean graft excursions before notchplasty. After notchplasty, all grafts tightened during knee flexion. Conclusions: Although errors in placement along the arc of the intercondylar notch did not significantly affect graft excursion patterns, the apparent graft tightening with knee flexion that was observed for all 3 tunnel positions after notchplasty suggests that graft forces would increase with knee flexion over this range. This would indicate that as little amount of bone as possible should be removed from the posterior portion of the intercondylar notch in ACL reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 4 (April), 2003: pp 340–345     

Metalloproteases and their inhibitors are altered in both torn and intact rotator cuff tendons

This article describes an anatomic, double-bundle, arthroscopic anterior cruciate ligament reconstruction technique with hamstrings using second-generation out-in retrograde femoral drills, second-generation cortical femoral suspensory fixation devices with adjustable graft loop length, standard out-in tibial drills, and titanium low-profile tibial staples. Grafts choice is autologous gracilis and semitendinosus tendons. They are harvested through the single minimally invasive tibial incision maintaining their tibial insertion. Sutures are tightened at the free proximal tendon ends to obtain a sufficient strength to traction. The grafts are reflected in two separate loops and linked to femoral adjustable TightRope graft loops. With this method, grafts length can be customized to the anatomy of every knee and their tension can be increased even after graft fixation. The preservation of tendons tibial insertion could improve the neoligamentization process, acting as a tenodesis.     

Effect of tibial tunnel dilation on pullout strength of semitendinosus-gracilis graft in anterior cruciate ligament reconstruction

This biomechanical cadaver study evaluated the effect of tibial tunnel dilation on the pullout strength of semitendinosus and gracilis tendon grafts in anterior cruciate ligament reconstruction. Fourteen grafts were harvested, and the anterior cruciate ligament was reconstructed in the tibial and femoral tunnels. All femoral tunnels were reamed to the diameter of the graft. In seven knees, the tibial tunnels were reamed to the diameter of the graft. In the remaining seven knees, the tibial tunnels were reamed 2 mm smaller than the diameter of the graft and then serially dilated to the graft size using cannulated smooth dilators. Mechanical testing to graft failure was conducted. All grafts failed by graft pullout from the tibial tunnel. However, mean peak load was significantly higher for the dilated tibial specimens (616 +/- 263 N) than for the reamed specimens (453 +/- 197 N) (P = .0025).     

Loss of knee extension after anterior cruciate ligament reconstruction: effects of knee position and graft tensioning

BACKGROUND: Loss of knee extension has been reported by many authors to be the most common complication following anterior cruciate ligament reconstruction. The objective of this in vitro study was to determine the effect, on loss of knee extension, of the knee flexion angle and the tension of the bone-patellar tendon-bone graft during graft fixation in a reconstruction of an anterior cruciate ligament. METHODS: The anterior cruciate ligament was reconstructed with use of tibial and femoral bone tunnels placed in the footprint of the native anterior cruciate ligament in ten cadavers. The graft was secured with an initial tension of either 44 N (10 lb) or 89 N (20 lb) applied with the knee at 0 degrees or 30 degrees of flexion. The knee flexion angle was measured with use of digital images following graft fixation. RESULTS: Tensioning of the graft at 30 degrees of knee flexion was associated with loss of knee extension in this cadaver model. Graft tension did not affect knee extension under the conditions tested. CONCLUSIONS: The results suggest that one of the common causes of the loss of full knee extension may be diminished if the graft is secured in full knee extension when the tibial and femoral tunnels are placed in the footprint of the native anterior cruciate ligament. More importantly, even when the femoral and tibial tunnels are placed in the femoral and tibial footprints of the native anterior cruciate ligament, fixing a graft in knee flexion can result in the loss of knee extension.     

Arthroskopische Auff��llung von fehlplatzierten und erweiterten Bohrkan?len mit Beckenkammspongiosa bei Rezidivinstabilit?t nach Ersatzplastik des vorderen Kreuzbandes

Objective

Arhroscopically performed autologous bone grafting of the femoral or tibial tunnel after anterior cruciate ligament (ACL) reconstruction in symptomatic anterior knee instability.

Indications

Subjective and objective instability in cases with recurrent instability following ACL reconstruction with tibial or femoral tunnel malplacement and tunnel widening.

Contraindications

Open growth plates, severe osteoarthritic changes.

Surgical technique

Arthroscopic ACL graft resection and implant removal followed by debridement of the tunnel and the sclerotic tunnel walls. Cortical bone cylinders and cancellous bone grafts are harvested from the iliac crest and transplanted into the enlarged and malplaced tunnels. The harvest site may be filled with bone substitutes.

Results

Arthroscopic filling of malplaced or enlarged bone tunnels was performed in 42?patients (14?men, 28?women, age range 18?C37?years) with recurrent instability after ACL reconstruction. All patients presented with tunnel malplacement, while 38?patients also had tunnel widening. In 39?cases, a tibial bone graft was necessary; in 12?cases the femoral defect was filled with autologous bone. No complications, such as hematomas of infections, were observed. CT scans showed complete integration of the osseous grafts after 3?C6?months.     

Tunnel enlargement 5 years after anterior cruciate ligament reconstruction: a radiographic and functional evaluation

Purpose

The aetiology and clinical significance of enlargement of bone tunnels following anterior cruciate ligament (ACL) reconstruction remains controversial. This phenomenon has been attributed to biological factors and mechanical factors. We wanted to study the amount of femoral and tibial tunnel enlargement 5 years post-ACL reconstruction. By standardizing the type of femoral fixation, we also wanted to determine whether the type of tibial fixation had any bearing to the amount of tibial tunnel enlargement.

Methods

All patients who underwent arthroscopic hamstring autograft ACL reconstruction between January 2000 and December 2000 were identified. All grafts were fixed with close-looped endobutton proximally. The grafts were fixed on the tibial side with staples or bioabsorbable interference screws. At a minimum of 5 years after surgery, these patients were recalled. They were assessed with Lysholm knee, Tegner activity and the IKDC Subjective and Objective forms and a KT-1000 arthrometer. The diameter of the bone tunnels and tunnel positions in the anterior–posterior and lateral radiographs were measured using digital callipers by a two blinded researchers.

Results

We found that the femoral tunnel enlarged more than the tibial tunnel. At 5 years, the mean tibial tunnel enlargement was 2.46 mm and the mean femoral tunnel enlargement was 3.23 mm. All 54 patients had endobutton femoral fixation. Of them, 34 patients had tibial graft fixation with staples (extracortical fixation) and 20 patients had tibial graft fixation with bioabsorbable interference screws (aperture fixation). The mean enlargement as measured by the two independent observers in the extracortical group was 1.98 mm (24.7 %)* and 1.51 mm (18.2 %)**compared to 3.27 mm (40.4 %)* and 2.92 mm (30.0 %)** in the aperture fixation group. This difference in tibial tunnel enlargement between the groups was significant (p < 0.001, mean difference 1.29 mm). However, this was not correlated with any significant difference in clinical outcome at 5 years.

Conclusion

We, like some authors, have shown that the use of interference screws in tibial fixation despite being aperture fixation actually has a greater amount of tibial enlargement. This lends weight to the biological theory to tunnel enlargement.     

Bone graft for tibial defects in total knee arthroplasty

Twenty-four knees with bone grafts for tibial defects at the time of either primary or revision total knee arthroplasty were followed for three to six years. With 22 of 24 bone grafts, union and revascularization were seen and no clinical collapse was present. In two, nonunion occurred, accompanied by collapse in one. Failure was attributed to varus alignment of the leg in one (a medial condylar graft) and to insufficient preparation of the bony bed in the second (bleeding bone was not exposed). Evidence for incorporation of the grafts was obtained by tomogram, bone scan, and bone biopsy. Incorporation was present by six months, but the time to complete remodeling was not determined. A bone graft is recommended for tibial defect involving 50% or more of the bony support of either tibial plateau. A bone graft is indicated whenever a cement column under the prosthesis would measure more than 5 mm in height.     

Anatomische vordere Kreuzbandersatzoperation mittels Semitendinosus- und Grazilissehne in fremdmaterialfreier Press-fit-Technik

An innovative technique for anterior cruciate ligament (ACL) reconstruction has been developed in 1998 which allows the grafts to be fixed by press-fit to the femoral and tibial tunnel without any hardware. The semitendinosus (ST) and gracilis tendons (GT) are built into a sling by tying a knot with the tendon ends and securing the knot after conditioning by sutures. For the femoral tunnel the anteromedial porta is used. The correct anatomic position of the single femoral tunnel is checked using intraoperative lateral fluoroscopy by placing the tip of a K-wire to a point between the anteromedial and posterolateral bundle insertion sites. A femoral bottleneck tunnel is drilled to receive the knot of the tendons. The tendon loops filled the tibial tunnel without any suture material. The loops are fixed at the tibial tunnel outlet with tapes over a bone bridge. Between 1998 and 1999 a prospective randomized study (level 1) was conducted comparing this technique with a technique using bone-patellar-tendon graft and press-fit fixation without hardware. In conclusion it was found that implant-free press-fit ACL reconstruction using bone-patella-tendon (BPT) and hamstring tendon (HT) grafts proved to be an excellent procedure to restore stability and function of the knee. Using hamstring tendons (ST and GT) significantly lower donor site morbidity was noted. Kneeling and knee walking pain persisted to be significantly more intense in the BPT up to 9 years after the operation. Re-rupture rates, subjective findings, knee stability and isokinetic testing showed similar results for both grafts. This is the first level I study which demonstrates cartilage protection by ACL reconstruction as long as the meniscus is intact at index surgery, shown by bilateral MRI analysis 9 years post-operation. There was no significant difference in the average grade of chondral and meniscus lesions between BPT and HT and in comparison of the operated to the intact knee, except for grade 3-4 lesions found at the 9 year follow-up, which were significantly higher in the BPT group.     

自体骨修复初次全膝关节置换术中胫骨骨缺损的临床研究

目的为了探讨初次全膝关节置换术中自体骨修复胫骨平台骨缺损患者植骨处的骨密度变化及骨愈合情况,对自体骨修复胫骨平台骨缺损患者的随访探讨。方法收集2008年6月至2010年3月,在15例（16膝）初次全膝关节置换术中,采用自体骨移植的方法修复胫骨平台骨缺损的患者。对照组收集同期的14例（16膝）无骨缺损患者。应用X线拍片及双能X线骨密度仪（DEXA）观察术后6个月、12个月时胫骨假体下骨密度。分为3个兴趣区（ROI）,对各个区内平均骨密度变化进行观察和分析。结果术后6个月时胫骨平台骨缺损处ROI的骨密度：（0.967±0.320）g/cm2,对照组ROI的骨密度：（0.946±0.263）g/cm2;术后12个月时胫骨平台骨缺损处ROI的骨密度：（0.808±0.258）g/cm2,对照组ROI的骨密度：（0.806±0.262）g/cm2。术后12个月时胫骨平台骨缺损植骨处平均骨密度较6个月时均数略有下降,但无统计学差异（P〉0.05）;术后6个月与12个月时胫骨平台骨缺损自体骨植骨处平均骨密度较无骨缺损患者ROI的骨密度无显著性差异（P〉0.05）。结论自体骨修复胫骨平台骨缺损的全膝关节置换术后患者植骨处骨密度较无骨缺损患者的骨密度无明显变化,骨愈合情况良好。     

Effects of femoral tunnel placement on knee laxity and forces in an anterior cruciate ligament graft.

The purpose of this study was to measure the effects of variation in placement of the femoral tunnel upon knee laxity, graft pretension required to restore normal anterior-posterior (AP) laxity and graft forces following anterior cruciate ligament (ACL) reconstruction. Two variants in tunnel position were studied: (1) AP position along the medial border of the lateral femoral condyle (at a standard 11 o'clock notch orientation) and (2) orientation along the arc of the femoral notch (o'clock position) at a fixed distance of 6-7 mm anterior to the posterior wall. AP laxity and forces in the native ACL were measured in fresh frozen cadaveric knee specimens during passive knee flexion-extension under the following modes of tibial loading: no external tibial force, anterior tibial force, varus-valgus moment, and internal-external tibial torque. One group (15 specimens) was used to determine effects of AP tunnel placement, while a second group (14 specimens) was used to study variations in o'clock position of the femoral tunnel within the femoral notch. A bone-patellar tendon-bone graft was placed into a femoral tunnel centered at a point 6-7 mm anterior to the posterior wall at the 11 o'clock position in the femoral notch. A graft pretension was determined such that AP laxity of the knee at 30 deg of flexion was restored to within 1 mm of normal; this was termed the laxity match pretension. All tests were repeated with a graft in the standard 11 o'clock tunnel, and then with a graft in tunnels placed at other selected positions. Varying placement of the femoral tunnel 1 h clockwise or counterclockwise from the 11 o'clock position did not significantly affect any biomechanical parameter measured in this study, nor did placing the graft 2.5 mm posteriorly within the standard 11 o'clock femoral tunnel. Placing the graft in a tunnel 5.0 mm anterior to the standard 11 o'clock tunnel increased the mean laxity match pretension by 16.8 N (62%) and produced a knee which was on average 1.7 mm more lax than normal at 10 deg of flexion and 4.2 mm less lax at 90 deg. During passive knee flexion-extension testing, mean graft forces with the 5.0 mm anterior tunnel were significantly higher than corresponding means with the standard 11 o'clock tunnel between 40 and 90 deg of flexion for all modes of constant tibial loading. These results indicate that AP positioning of the femoral tunnel at the 11 o'clock position is more critical than o'clock positioning in terms of restoring normal levels of graft force and knee laxity profiles at the time of ACL reconstruction.     

Femoral component fracture due to osteolysis after cemented mobile-bearing total knee arthroplasty

A 58-year-old man with osteoarthritis in the left knee underwent a total knee arthroplasty with a New Jersey anterior-posterior gliding low contact stress mobile-bearing implant. All femoral, tibial, and patellar components were implanted with bone cement. Pain developed at 43 months postsurgery, and plain radiography revealed a vertical crack in the femoral component and osteolysis at the medial femoral condyle. The femoral and tibial components were revised, and the bone defect at the medial femoral condyle was reconstructed using an allogeneic strut bone graft. Microscope examination identified polyethylene particles with foreign body granulomatous reaction, and scanning electron microscopy revealed fatigue failure of the femoral component. Osteolysis due to polyethylene particles can lead to fracture of the femoral component after cemented anterior-posterior gliding low contact stress mobile-bearing total knee arthroplasty.     

血栓闭塞性脉管炎合并动脉硬化闭塞导致下肢缺血的手术治疗

目的 探讨下肢血栓闭塞性脉管炎(thmmboangiitis obliterans,TAO)合并动脉硬化闭塞症(arteriosclerosis obliterans,ASO)手术治疗效果.方法 回顾性分析2007年治疗的TAO合并ASO 6例患者的资料.2例行腹主动脉切开取栓+内膜剥脱+腹主动脉-股深动脉人工血管旁路移植-胭动脉人工血管-小腿动脉自体大隐静脉旁路移植术,1例行腹主动脉切开取栓+内膜剥脱+腹主动脉-右股深动脉人工血管旁路移植-膝下胭动脉人工血管旁路移植术;1例行左髂总动脉-左股深动脉人工血管旁路移植一胫前动脉自体大隐静脉原位移植术,1例行左侧人工血管切开取栓+左股深动脉成形-膝下腘动脉人工血管旁路移植术,1例行右股总动脉-左股总动脉人工血管旁路移植-胫后动脉自体大隐静脉旁路移植术.结果 5例患者术后恢复顺利,1例于术后当天出现股动脉-腘动脉人工血管和远段的大隐静脉桥血栓形成,立即再次手术行人工血管和大隐静脉切开取栓术,并同时行胫后动静脉吻合.6例患者均痊愈出院,无死亡病例.5例患者的下肢远端静息痛完全缓解,1例部分缓解.足部溃疡的2例创面明显缩小,无感染发生.所有患者得到随访,平均随访为6.5个月,3例足部溃疡愈合.1例术后3个月出现左股部切口感染,最终行膝上截肢处理,残端一期愈合.其他5例患者的移植血管通畅,症状缓解.结论 对TAO合并ASO患者如果手术治疗方式恰当,可以取得比较好的疗效.     

Femoral bone grafting in primary and revision total knee arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results of TKA's with morsellized and solid femoral bone grafting. From April 1989 to February 1996, 6 primary and 18 revision TKA's with femoral bone grafting were performed in 22 patients with an average age of 62 years. Eleven knees were affected by rheumatoid arthritis, 10 by osteoarthritis, 2 by osteonecrosis and one by hemophiliac arthropathy. The femoral bone defects were large in 12, medium in 9, small in 3, contained in 10 and uncontained in 14 cases. Reconstruction was done with impacted morsellized fresh frozen trabecular bone grafts in 13 knees, with solid bone grafts in 7 knees and with combined grafts in 4 knees. Twenty-one cases were clinically evaluated at an average of 38 months (range: 9-89 months). The average Knee Society knee score increased by 39 points to 85 points at follow-up. The average functional score increased by 22 points to 48 points. Two cases with solid femoral bone grafts failed due to aseptic loosening. There were no infections. Radiographic follow-up revealed osteopenia around the femoral component in 10 knees. Two knees showed circumferential radiolucency around the femoral stem, and 5 knees had minor radiolucency at the anterior part of the femoral component. Radiographic incorporation was present in 5 of the 6 cases that could be evaluated. Histologic analysis of two biopsies revealed incorporation of the morsellized bone graft. The authors advocate impacted morsellized bone grafting for contained and small-to-medium uncontained femoral bone defects in combination with cemented TKA.     

Revascularisation of fresh compared with demineralised bone grafts in rats.

Revascularisation of bone grafts is influenced by both the anatomical origin and the pre-implantation processing of the graft. We investigated the revascularisation by entrapment of 141Ce (cerium)-labelled microspheres in large, fresh and demineralised syngeneic grafts of predominantly cancellous (iliac bone) or cortical (tibial diaphysis) bone three weeks after heterotopic implantation in rats. The mean (SD) 141Ce deposition index (counts per minute (cpm) of mg recovered implant/cpm of mg host iliac bone) was higher in fresh iliac bone grafts, 0.98 (0.46) compared to that of demineralised iliac bone, 0.32 (0.20), p < 0.001, and fresh tibial bone grafts, 0.51 (0.27), p = 0.007. We found no significant difference in the mean 141Ce deposition index between fresh tibial bone grafts and demineralised tibial bone grafts, 0.35 (0.42), p = 0.4, or between demineralised tibial grafts and demineralised iliac bone grafts, p = 0.8. The results suggest that whereas fresh cancellous grafts are revascularised more completely than fresh cortical grafts, there is no difference in the revascularisation of demineralised cancellous and cortical grafts. In addition, fresh cancellous bone is revascularised more completely than demineralised cancellous bone, whereas there is no difference between fresh and demineralised cortical bone.     

Editorial Commentary: Anterior Cruciate Ligament Graft Tunnel Mismatch: The Long and Short of It

Anterior cruciate ligament graft size is an important consideration when planning the length of the tibial tunnel. In general, longer grafts require longer tunnels to accommodate the graft. Ideally, the tibial bone plug should be flush with the tibial cortex after graft passage and femoral fixation. Alternatively, allograft bone-patellar tendon-bone grafts can be selected based on their lengths to assure an ideal fit in the tibial tunnel. However, there are increased risks of allograft failure in young patients that anterior cruciate ligament surgeons should recognize.     

Knee stability and graft function following anterior cruciate ligament reconstruction: Comparison between 11 o'clock and 10 o'clock femoral tunnel placement

Purpose: To study how well an anterior cruciate ligament (ACL) graft fixed at the 10 and 11 o'clock positions can restore knee function in response to both externally applied anterior tibial and combined rotatory loads by comparing the biomechanical results with each other and with the intact knee. Type of Study: Biomechanical experiment using human cadaveric specimens. Methods: Ten human cadaveric knees (age, 41±13 years) were reconstructed by placing a bone–patellar tendon–bone graft at the 10 and 11 o'clock positions, in a randomized order, and then tested using a robotic/universal force-moment sensor testing system. Two external loading conditions were applied: (1) 134 N anterior tibial load with the knee at full extension, 15°, 30°, 60°, and 90° of flexion, and (2) a combined rotatory load of 10 N-m valgus and 5 N-m internal tibial torque with the knee at 15° and 30° of flexion. The resulting kinematics of the reconstructed knee and in situ forces in the ACL graft were determined for each femoral tunnel position. Results: In response to a 134-N anterior tibial load, anterior tibial translation (ATT) for both femoral tunnel positions was not significantly different from the intact knee except at 90° of knee flexion as well as at 60° of knee flexion for the 10 o'clock position. There was no significant difference in the ATT between the 10 and 11 o'clock positions, except at 90° of knee flexion. Under a combined rotatory load, however, the coupled ATT for the 11 o'clock position was approximately 130% of that for the intact knee at 15° and 30° of flexion. For the 10 o'clock position, the coupled ATT was not significantly different from the intact knee at 15° of flexion and approximately 120% of that for the intact knee at 30° of flexion. Coupled ATT for the 10 o'clock position was significantly smaller than for the 11 o'clock position at 15° and 30° of flexion. The in situ force in the ACL graft was also significantly higher for the 10 o'clock position than the 11 o'clock position at 30° of flexion in response to the same loading condition (70 ± 18 N v 60 ± 15 N, respectively). Conclusions: The 10 o'clock position more effectively resists rotatory loads when compared with the 11 o'clock position as evidenced by smaller ATT and higher in situ force in the graft. Despite the fact that ACL grafts placed at the 10 or 11 o'clock positions are equally effective under an anterior tibial load, neither femoral tunnel position was able to fully restore knee stability to the level of the intact knee.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 297–304