Stiffness after total knee arthroplasty

Method for quantifying patient expectations and early recovery after total knee arthroplasty

Many components of a surgeon's total knee arthroplasty (TKA) treatment regimen affect the rate of recovery, such as patient selection, preoperative education, surgical technique, pain management, and postoperative rehabilitation. Therefore, accurate counseling requires that the surgeon quantifies patient expectations and early recovery of the treatment regimen with a method that minimizes interviewer bias. Preoperatively and 4 to 5 weeks after TKA, 285 patients (306 consecutive primary TKAs) responded to a survey consisting of customized questions, the Oxford score, the SF-12, and Knee Society scores on a handheld data acquisition device. The average response to each question on the 4- to 5-week postoperative survey defined patient expectations, and the change in a response between the 4- to 5-week postoperative and the preoperative survey determined whether the surgical intervention improved the patient. At 4 to 5 weeks postoperatively, 80% of patients walked without a cane, 54% drove a car, 88% thought the treated knee was functioning better than before surgery, 93.5% thought the treated knee was normal or nearly normal, and 98% thought the alignment of their limb was "just right." By 4 to 5 weeks, patients experienced less pain and showed significant improvements in 11 of 12 activities queried by the Oxford score, SF-12 physical score, Knee function score, Knee Society score, and knee extension. Flexion was significantly less at 4 to 5 weeks, and the SF-12 mental score was not significantly different. Average hospital stay was 2 nights, with 98% discharged home. Surgeons should consider a method that minimizes interviewer bias to quantify patient expectations and rate of recovery of their specific treatment regimen, and then use this information to counsel their patients to avoid disappointment after TKA.

Reactive oxygen and nitrogen species induce protein and DNA modifications driving arthrofibrosis following total knee arthroplasty

Background

Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation.

Results

We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed in both macrophages and fibroblasts in arthrofibrotic tissue. As direct measurement of ROS/RNS is not feasible, products including DNA hydroxylation (8-OHdG), and protein nitrosylation (nitrotyrosine) were measured by immunohistochemistry. Quantification of the staining showed that 8-OHdg was significantly increased in arthrofibrotic tissue. There was also a direct correlation between the intensity of inflammation and ROS/RNS to the amount of heterotopic ossification (HO). In order to investigate the aberrant expression of MPO, a real-time oxidative stress polymerase chain reaction array was performed on fibroblasts isolated from arthrofibrotic and control tissues. The results of this array confirmed the upregulation of MPO expression in arthrofibrotic fibroblasts and highlighted the downregulated expression of the antioxidants, superoxide dismutase1 and microsomal glutathione S-transferase 3, as well as the significant increase in thioredoxin reductase, a known promoter of cell proliferation, and polynucleotide kinase 3'-phosphatase, a key enzyme in the base excision repair pathway for oxidative DNA damage.

Conclusion

Based on our current findings, we suggest that ROS/RNS initiate and sustain the arthrofibrotic response driving aggressive fibroblast proliferation and subsequent HO.

Assessment of isometricity before and after total knee arthroplasty: a cadaver study

Total knee arthroplasty (TKA) relies on soft tissue to regulate joint stability after surgery. In practice, the exact balance of the gaps can be difficult to measure, and various methods including intra-operative spreaders or distraction devices have been proposed. While individual ligament strain patterns have been measured, no data exist on the isometricity of the soft tissue envelope as a whole. In this study, a novel device was developed and validated to compare isometricity in the entire soft tissue envelope for both the intact and TKA knee. A spring-loaded rod was inserted in six cadaver knee joints between the tibial shaft and the tibial plateau or tibial tray after removing a 7 mm slice of bone. The displacement of the rod during passive flexion represented variation in tissue tension around the joint. The rod position in the intact knee remained within 1 mm of its initial position between 15 degrees and 135 degrees of flexion, and within 2 mm (+/-1.2 mm) throughout the entire range of motion (0-150 degrees). After insertion of a mobile-bearing TKA, the rod was displaced a mean of 6 mm at 150 degrees (p<0.001). The results were validated using a force transducer implanted in the tibial baseplate of the TKA, which showed increased tibiofemoral force in the parts of the flexion range where the rod was most displaced. The force measurements were highly correlated with the displacement pattern of the spring-loaded rod (r=-0.338; p=0.006). A simple device has been validated to measure isometricity in the soft tissue envelope around the knee joint. Isometricity measurements may be used in the future to improve implantation techniques during TKA surgery.

Differences between the sexes in the anatomy of the anterior condyle of the knee

BACKGROUND

Claims that there are dramatic differences in anterior condylar anatomy between the sexes have led to the design of total knee implants with thinner anterior condyles specifically for use in women. We had observed, in our patients, differences in anterior condylar anatomy that appeared to be highly variable and dependent on the size, height, and ethnicity of the patient as well as his or her sex. Because of this observed variability, we sought to determine if differences in anterior condylar anatomy between the sexes actually exist.

METHODS

Two hundred and twelve randomly selected magnetic resonance images (112 of men and 100 of women) were evaluated. The anterior condyle was defined as the area of bone anterior to the anterior femoral cortex, 10 mm above the joint line. The medial and lateral heights of the anterior condyles were measured in millimeters directly from magnetic resonance imaging data obtained in two planes. The so-called aspect ratio was calculated to determine whether patient size had an effect on the size of the anterior condyles.

RESULTS

On the basis of the numbers available, there was no significant difference (p = 0.16) between the sexes with regard to lateral condylar height. The average difference was only 0.5 mm. There was a significant difference (p = 0.001) between men and women with regard to medial condylar height. However, the average difference was only 1.1 mm. While the difference between the sexes with regard to anterior condylar height was nominal, the measurements were highly variable regardless of sex. On the basis of the numbers available, there were no significant differences between men and women with regard to the condylar aspect ratios.

CONCLUSIONS

The difference in anterior condylar anatomy is mentioned as one of three reasons for the need for a so-called gender-specific knee implant. The aspect ratio reported here, which is a surrogate for patient size, seems to negate any difference in anterior condylar anatomy based on sex. We have shown that anterior condylar anatomy is highly variable regardless of sex. We believe that implants as well as surgical techniques should be designed with the variability of anterior condylar anatomy taken into account and with an attempt to reproduce such anatomy regardless of sex.

Evaluation of a custom device for the treatment of flexion contractures after total knee arthroplasty

Knee flexion contractures can severely impair function after total knee arthroplasties. We evaluated the use of a custom-molded knee device to treat 47 patients who had knee flexion contractures (mean, 22 degrees; range, 10 degrees-40 degrees) after primary or revision total knee arthroplasties and who had failed conventional therapeutic methods. The device was used for 30 to 45 minutes per session two to three times per day in conjunction with standard physical therapy modalities two to three times per week. Twenty-seven of 29 patients who underwent primary total knee arthroplasty and 13 of 18 patients who underwent revisions achieved full extension after a mean treatment time of 9 weeks (range, 6-16 weeks). Full knee extension was maintained at a minimum followup of 18 months (mean, 24 months; range, 18-36 months). The mean Knee Society knee and functional scores improved from 50 points and 34 points to 91 points and 89 points, respectively. This protocol had comparable rates of improvement in knee extension with less treatment time when compared with other nonoperative treatments reported in the literature. The custom knee device may be a useful adjunct to a physical therapy regimen for knee flexion contractures after total knee arthroplasty.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Supracondylar femur fracture after knee manipulation: a report of 3 cases

Supracondylar femur fracture is a rare but devastating complication of knee manipulation following total knee arthroplasty (TKA). Avoidance of this complication can be achieved by careful attention to the indications and contraindications, timing, and technique of closed manipulation. We performed a retrospective chart and radiographic review to identify all patients who underwent closed manipulation under anesthesia for a diagnosis of aseptic arthrofibrosis after TKA. This article presents 3 cases of supracondylar femur fracture following closed knee manipulation of stiff TKAs that occurred at our institution over a 4-year period (1999-2002). Patient age ranged from 44 to 73 years. All patients underwent cruciate retaining TKA. Time from TKA to manipulation ranged from 3 months to 3 years. Two patients sustained an extension type supracondylar fracture. Two of the 3 patients were treated with closed reduction and casting/bracing. At a minimum 8-month follow-up after fracture, range of motion was poor with average flexion to 77 degrees and average flexion contracture of 13 degrees . In our patients, risk factors for fracture included prolonged time from arthroplasty to manipulation, arthrofibrosis, radiographic osteopenia, and rheumatoid arthritis. To our knowledge, this represents the largest case series of iatrogenic supracondylar femur fractures reported in the literature. Two manipulation techniques are described in detail. The alternative manipulation technique is highlighted with no fractures or complications over the same period. We believe that the alternative manipulation technique is a safe and effective technique to manipulate stiff TKA's and has been used for over >10 years by the senior surgeon (J.V.B.).

Minimally Invasive Surgical Technique in Total Knee Arthroplasty: A Learning Curve

Clinical experience of learning a new technique of minimally surgery for total knee arthroplasty is presented. Close monitoring of the technique, pitfalls, learning tips, and tricks are discussed. A “learning phase” is identified as approximately 10 months or 21 knee replacements using minimally invasive technique. It took 50 operations before the surgical time equaled the open technique. There was no incidence of increased complications during the learning phase. Functional results such as stair climbing, walking distance, and walking with aids was significantly better after minimally invasive technique than after standard technique.

Kinematics of the stiff total knee arthroplasty

The kinematics of 10 total knee replacements with poor flexion (<90 degrees ) were compared with 11 replacements with good flexion (>110 degrees ) at a mean of 3 years from surgery using optical calibration with implant shape-matching techniques from radiographs taken in standing, early-lunge, and late-lunge positions. There were no significant differences between groups in anteroposterior translation of the medial and lateral femoral condyles or tibial rotation during standing and early lunge. Groups differed in amount of posterior translation of the femoral condyles during late lunge because of the poor-flexion group's inability to achieve the same amount of flexion as the good-flexion group. Poor flexion after total knee arthroplasty, we conclude, is not associated with abnormal kinematics in the setting of well-aligned, well-fixed implants.

Static progressive stretch for the treatment of knee stiffness

Persistent knee stiffness is common after knee arthroplasties, cruciate ligament repairs, and trauma. Static progressive stretch protocols have shown success in treating contractures of the elbow, ankle, and knee in case reports and small case series. This study evaluated static progressive stretch as a treatment method for patients who had refractory knee stiffness, and compared the outcomes to published results of other therapeutic modalities. Forty-one patients who had knee stiffness and who had not improved with conventional physical therapy modalities were treated with a patient-directed orthosis that utilized the principles of static progressive stretch. After a mean of 9 weeks of use (range, 3 to 27 weeks), the total arc of motion increased by a mean of 33 degrees (range, 0 to 85 degrees ). Forty of 41 patients had increased motion at a mean final follow-up time of 1 year (range, 6 months to 2 years), and 93% were satisfied with the results. The outcomes were comparable to other nonoperative treatments reported in the literature, but the results in the present study occurred in a shorter mean treatment time. An orthosis that utilizes the principles of static progressive stretch may be a successful treatment for improving the range of motion and satisfaction of patients who have knee contractures.

Clinical experience with less invasive surgery techniques in total knee arthroplasty: a comparative study

We compared 25 consecutive cases of total knee arthroplasty performed through less invasive techniques with 25 cases of age and BMI matched cases of standard knee replacements. Early experience suggests functional recovery is earlier with less invasive technique as compared with open access. Patients in less invasive group had better knee flexion (an average of 116 degrees compared to 97 degrees ), walking ability and stair climbing at 6 months than those with standard technique at 6 months. At 2 years this difference was maintained to a lesser extent. More patients with less invasive group could kneel and could do "normal up and down" the stairs at 6 months and also at 2 years. There was no significant difference in alignment and component sizing between the two groups. This should translate to similar long term results after less invasive knee arthroplasty as after open access total knee arthroplasty.

Results of contralateral total knee arthroplasty in patients with a history of stiff total knee arthroplasty

This study seeks to evaluate the clinical outcomes of a second primary total knee arthroplasty in patients whose initial (contralateral) primary total knee arthroplasty was complicated by stiffness. We retrospectively compared the preoperative and postoperative range of motion and Knee Society Scores from a study group of 15 patients with an age-matched control group. Statistical analysis did not reveal a significant difference in final postoperative range of motion or Knee Society Scores between the 2 groups. However, there was a statistically significant higher rate of closed manipulation in the study group. Therefore, although the study group did show a higher rate of early stiffness, eventual functional outcome was comparable with a nonstiffness control group.

The impact of minimally invasive surgical techniques on early range of motion after primary total knee arthroplasty

A single surgeon performed 200 consecutive primary total knee arthroplasties using identical implants. One hundred of these were done using a traditional medial parapatellar arthrotomy. The other knees were done using a medial parapatellar approach combined with minimally invasive surgical techniques. Patients in the minimal incision group had shorter incision length, shorter length of stay, and less pain (P < .01). Moreover, those patients in the minimal incision group had less flexion contracture (P < .05) and better flexion (P < .05) in the first 12 weeks. Manipulation was necessary in 14% of the traditional group compared with 2% in the minimal incision group (P < .001). There was no significant difference in range of motion or functional outcome at 1 year after surgery. There was no significant difference in component position or complication rates.

The results of knee manipulation for stiffness after total knee arthroplasty with or without an intra-articular steroid injection

BACKGROUND

Stiffness after total knee arthroplasty (TKA) requiring manipulation has a reported incidence of 1.3-54%. The purpose of this study was to compare the incidence of stiffness warranting manipulation using two different pain management protocols. We also studied the effect of an intra-articular injection of local anesthetic and steroid given at the time of manipulation on the range-of-motion (ROM) at last follow-up.

MATERIALS AND METHODS

A total of 286 TKAs (248 patients between January 2002 and December 2003) were compared to a second group of 292 TKAs (251 patients between January 2004 and March 2006). The first group received patient-controlled analgesia (PCA) for postoperative pain management. The second group had a peri-articular injection of a steroid-containing local anesthetic at the time of surgery, but no postoperative PCA. All patients undergoing manipulation in the second group also received a similar intra-articular injection at the time of manipulation as well. Only patients with minimum 12 months follow-up after manipulation were included in the study.

RESULTS

The overall incidence of stiffness requiring manipulation in both groups was similar at 2.4% and 2.1%, respectively (P = 0.1). The end results of manipulation with and without injection showed a significantly higher final ROM in patients who had had an injection at the time of manipulation (P = 0.001). The difference was due to the fact that patients who had an injection lost no motion from that achieved at the time of manipulation.

CONCLUSION

We were unable to demonstrate a significant reduction in the incidence of stiffness after TKA using a modern pain management protocol. However, injection of a local anesthetic and steroid at the time of manipulation did have a significant influence on preserving the ROM that was obtained at the time of manipulation.

Complex regional pain syndrome with special emphasis on the knee

Complex regional pain syndrome is characterised by an exaggerated response to injury in a limb with intense prolonged pain, vasomotor disturbance, delayed functional recovery and trophic changes. This review describes the current knowledge of the condition and outlines the methods of treatment available with particular emphasis on the knee.

Early and late manipulation improve flexion after total knee arthroplasty

Manipulations have been considered effective only in the early postoperative period. From a total joint registry containing 9640 primary total knee arthroplasties (TKAs), 195 patients who underwent manipulation under anesthesia (MUA) were identified. A total of 102 had MUA within 90 days (early), and 93 more than 90 days (late) after TKA. Average pain (10-point scale), satisfaction (10-point scale), flexion (degrees), and extension (degrees) were recorded before and after MUA. Flexion was significantly improved after MUA for both groups: early MUA from 68.4 degrees (+/-17.2 degrees ) to 101.4 degrees (+/-16.15 degrees ), P < .001; late MUA from 81.0 degrees (+/-13.3 degrees ) to 98.0 degrees (+/-18.0 degrees ), P = .001. Pain decreased significantly with early MUA from 4.92 (+/-2.25) to 3.34 (+/-2.67) and with late MUA from 4.51 (+/-2.62) to 3.44 (+/-2.78), P = .048. Extension improved only in the early MUA group from 7.15 (+/-10.1) to 2.50 (+/-4.98). Satisfaction scores were not improved. Both early and late manipulation can improve TKA pain and flexion.

Etiology and surgical interventions for stiff total knee replacements

Stiffness is the most prevalent early local complication of primary total knee replacement, affecting approximately 6 to 7% of patients undergoing surgery. The definition of stiffness after total knee replacement in terms of restriction of the arc of motion has evolved in the last 2 decades as patients and physicians expect better postoperative functional outcomes. Gentle manipulation under anesthesia within 3 to 4 months of surgery improves the range of motion in most patients. However, approximately 1% of patients, including those in which the window for manipulation has passed, will require further surgical interventions, which may include arthroscopy with lysis of adhesions, open debridement with exchange of the polyethylene insert, or revision of one or more components. This review will focus on describing the etiology of the problem and the results of the different surgical interventions for stiffness after total knee replacement.

Early revision for component malrotation in total knee arthroplasty

Component malrotation may result in unsuccessful total knee arthroplasty. We asked whether revision improves function in patients with malrotated total knee arthroplasty components. We retrospectively reviewed 22 revision total knee arthroplasties performed for femoral and/or tibial component malrotation. Revision surgery was performed within 2 years of the primary arthroplasty in 81% of the cases (18 of 22) with the remainder within 5 years. Although all patients had pain, 32% of patients had associated instability and 36% of patients had poor range of motion. Average Knee Society Scores improved from 42 preoperatively to 77 postoperatively. Average Oxford Knee Scores improved from 38 preoperatively to 29 postoperatively. Although clinical and functional improvement was observed, these results are inferior to those for primary knee arthroplasty, and they emphasize the need for proper component rotational positioning during primary total knee arthroplasty. Internal component malrotation leads not only to patellofemoral problems, but also to difficulty in gap balancing and femoral component sizing, which may in turn lead to either poor range of motion or symptoms of knee instability.

Total joint replacement surgery in a rural centre

OBJECTIVE

To demonstrate that total joint replacement surgery can be safely and effectively performed in rural hospitals with acceptable outcomes.

DESIGN

Case series.

SETTING

A rural district hospital.

PARTICIPANTS

PARTICIPANTS were 64 patients, 30 men and 34 women, who underwent total knee replacements (TKR); and 63 patients, 41 men and 22 women, who had total hip replacements (THR).

MAIN OUTCOME MEASURES

Level of patient satisfaction following total joint replacement surgery, obtained by patient interview. Incidence of postoperative joint specific complications, for example infection, THR dislocation and manipulation under anaesthetic (MUA) of a TKR.

RESULTS

None of the TKR or THR patients developed a deep wound infection. In this study 8.8% TKR patients had an MUA but all during a period of limited physiotherapy services; 5.8% THR patients suffered a dislocated prosthesis. Following TKR 95.3% patients reported to be 'happy' with the outcome of their surgery. Of the THR patients 97.0% declared they were 'happy' with their surgical outcome.

CONCLUSIONS

There was a high level of patient satisfaction, low infection rate, acceptable levels of MUA for TKR and dislocation for THR following total joint replacement in our rural district hospital. The surgeons performed a medium volume of total joint replacements and an appropriate multidisciplinary team was in place. In such settings joint replacement surgery can be safely and successfully performed in rural centres to the benefit of rural patients, surgeons and GPs.

Minimally invasive technique in total knee arthroplasty--history, tips, tricks and pitfalls

Minimally invasive surgery (MIS) in Total Knee Arthroplasty (TKA) has been evolving since the early 1990s and was first described by several authors from the USA in early 2003-4. The evolution was driven from patients and clinicians alike and the technique has been used by several experienced knee surgeons worldwide. Although the procedure is demanding and the learning curve long, the benefits outweigh the difficulties faced during the learning process. Our experience with minimally invasive techniques started in 2003. At the beginning only a few procedures were carried out as rigorous exclusion criteria were applied. However, as confidence grew the number of operations has significantly increased. The average surgical time for minimally invasive technique is longer than for the standard technique, particularly in the early stages. More attention needs to be paid to the alignment, sizing and positioning of the prosthesis. According to our early experience, functional recovery is faster with MIS compared with standard technique. The MIS group achieved better knee flexion during the first three months (average of 116 degrees ) compared to open access surgery (average of 97 degrees ). There was no significant difference in alignment and component sizing between the two groups.

Rapid recovery protocols and minimally invasive surgery help achieve high knee flexion

Although the primary goal of total knee arthroplasty is to relieve pain, the attainment of high flexion has emerged as an important secondary goal. Clinical pathways are evolving and focus on rapid recovery. The entire perioperative process for the patient and family, including office and hospital procedures, has been streamlined and patients are advised from the initial evaluation they will be able to quickly return to activities of daily living. Currently, patients are out of bed within hours of surgery, engaging in activities that require a substantial range of motion in the treated knee. They are frequently discharged directly to home within 24 to 48 hours. We retrospectively reviewed two groups of patients undergoing primary total knee arthroplasty whose perioperative management differed only by surgical approach, namely, standard versus less invasive. Refined perioperative protocols in combination with a less invasive, mini-arthrotomy approach using special instrumentation resulted in earlier discharge to home, higher range of motion and improved clinical and pain scores.

[Therapy of arthrofibrosis after total knee arthroplasty]

Arthrofibrosis is one of the most common complications after total knee arthroplasty with an overall incidence of approximately 10%. Nevertheless, published data are rare and clinical trials mostly include small and heterogeneous patient series resulting in controversial conclusions. Clinically, arthrofibrosis after knee arthroplasty is defined as (painful) stiffness with scarring and soft tissue proliferation. Differentiation between local (peripatellar) and generalized fibrosis is therapeutically relevant. Histopathology typically shows subsynovial fibrosis with synovial hyperplasia, chronic inflammatory infiltration, and excessive and unregulated proliferation of collagen and fibroblasts. Diagnostic strategies are based on the exclusion of differential causes for painful knee stiffness, and especially the exclusion of low-grade infections represents a diagnostic challenge. Early and intensive physiotherapy combined with sufficient analgesia should be initiated as a basic therapy. The next therapeutic steps for persisting arthrofibrosis include closed manipulation and open arthrolysis. Arthroscopic interventions should be limited to local fibrosis. Revision arthroplasty represents a rescue surgery, often associated with recurrence of fibrosis. Prevention of arthrofibrosis by sufficient analgesia and early physiotherapy remains the best treatment option for painful stiffness after knee arthroplasty.

Surgical treatment and customized rehabilitation for stiff knee arthroplasties

Treating patients who have arthrofibrotic or stiff knees after total knee arthroplasty can be difficult. Treatment with arthroscopic débridement, arthrolysis of adhesions with polyethylene spacer exchange, or complete revision arthroplasty often has led to less than optimal range of motion and functional outcomes. We used a combination of surgical arthrolysis and an intensive postoperative rehabilitation protocol, including functional bracing, to treat this condition. We then retrospectively reviewed 18 knees in 17 patients who had stiff knees after total knee arthroplasty with no other detectable clinical or radiographic abnormalities, at a mean followup of 30 months. Seventeen knees (94%) had gains in knee range of motion with a mean increased range of motion of 31 degrees. Although 16 of 17 patients had clinical improvement and were satisfied with the procedure, only (2/3) of the patients (12 of 18 patients) had excellent or good Knee Society objective scores. This combined surgical and rehabilitation method can lead to an increased range of motion. All patients improved clinically, but good functional results were less predictable. The authors think treatment of these difficult knees should be aimed at soft tissue operative releases supplemented by an intensive rehabilitation protocol.

LEVEL OF EVIDENCE

Therapeutic study, level IV (prospective study). See Guidelines for Authors for a complete description of levels of evidence.

Femoral component rotation and arthrofibrosis following mobile-bearing total knee arthroplasty

The purpose of this study was to evaluate the femoral component rotation in a small subset of patients who had developed arthrofibrosis after mobile-bearing total knee arthroplasty (TKA). Arthrofibrosis was defined as flexion less than 90 degrees or a flexion contracture greater than 10 degrees following TKA. From a consecutive cohort of 3,058 mobile-bearing TKAs, 49 (1.6%) patients were diagnosed as having arthrofibrosis, of which 38 (86%) could be recruited for clinical assessment. Femoral rotation of a control group of 38 asymptomatic TKA patients matched for age, gender, and body mass index was also evaluated. The surgical epicondylar axis was compared with the posterior condylar axis for the femoral prosthesis. Femoral components in the arthrofibrosis group were significantly internally rotated by a mean of 4.7 degrees (SD 2.2 degrees , range 10 degrees internal to 1 degrees external). In the control group, the femoral component had a mean 0.3 degrees internal rotation (SD 2.3 degrees , range 4 degrees internal to 6 degrees external). Following mobile-bearing TKA, there is a significant correlation between internal femoral component rotation and chronic arthrofibrosis.

Mechanical comparison of the Youngswick, sagittal V, and modified Weil osteotomies for hallux rigidus in a sawbone model

The purpose of this study was to compare the mechanical properties of 3 osteotomies often used for hallux rigidus. Maximum load, failure energy, stiffness, and fracture pattern were determined for 3 different test models as well as a control group. Twenty-eight first metatarsal polyurethane sawbone models were equally divided into 4 groups. The osteotomy groups tested consisted of a Youngswick, sagittal V, and modified Weil-type osteotomy of the first metatarsal. Each osteotomy was fixated with a 2.7-mm cortical screw, all 16 mm in length, and a small diameter smooth wire, both placed perpendicular to the osteotomy. Each model was then loaded to failure in a servo-hydraulic material testing machine. Results for maximum load to failure for all 4 constructs showed a mean range of 15.1 to 33.7 N, a mean energy to failure ranging from 0.04 to 0.8 J, and stiffness from 1.5 to 3.4 N/mm. Significant differences in peak load and stiffness (P = .015 for peak load, P = .025 for stiffness) were found between the sagittal V group versus the control and between the modified Weil and sagittal V group (P = .037 for peak load, P = .017 for stiffness). There were no significant differences in the energy to failure between the 4 groups (P > .083). These findings suggest that the sagittal V osteotomy construct was significantly weaker and less stiff than the modified Weil.

The effect of distal femoral resection on passive knee extension in posterior cruciate ligament-retaining total knee arthroplasty

Full passive extension in total knee arthroplasty is predicated on creating a large enough extension gap to accommodate any given combined thickness of femoral and tibial components. Additional distal femoral resection can achieve more passive knee extension. The predictable effect of further distal femoral resection has never been studied. We designed a simple institutional review board-approved, intraoperative study to quantify this effect. Routine posterior cruciate ligament-preserving total knee arthroplasty was performed with measured femoral and tibial resections, yielding full passive extension with trial components. Distal femoral augments were then sequentially applied to the back of the femoral trial component, and passive knee extension was measured. The data show that an average value of 9 degrees of femoral contracture is corrected for every 2 mm of distal femoral resection.

Revision total knee arthroplasty for restricted motion

Persistent stiffness is an infrequent but notable complication occurring after total knee arthroplasty. A limited approach (soft tissue releases and component retention with tibial insert downsizing) has previously been associated with poor results, although comprehensive revision of both components seems more successful. We retrospectively reviewed 23 patients (25 knees) who had revision total knee arthroplasty for painful limitation of motion. At a mean of 36.7 months after surgery we assessed pain, motion arc, and Knee Society clinical and functional scores. The effectiveness of a limited approach for selected patients (n = 12) was compared with more comprehensive revision of both components (n = 11). Patients with the limited approach had improvements in mean knee motion arc (25.7 degrees), mean clinical score (37.8 points), and mean functional score (20.8 points). Patients with component revision had a mean improvement in knee motion arc (17.9 degrees) but little change in the clinical score (3.6 points) or functional score (-1.0 points). The severity of preoperative flexion contractures and limited motion in patients having component revision likely contributed to the limited improvement. The data suggest a limited soft tissue approach may be appropriate for a select group of patients. The success of component revision for patients with severely restricted motion and more extensive flexion contracture was less predictable than authors of previous reports suggest.

LEVEL OF EVIDENCE

Therapeutic study, Level III-1 (retrospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.